Consulta: creatorFacets:"Fromentin, Jean-marc"
Registros recuperados: 129
Data/hora: 07/06/2024 05:45:34

Year-to-Year changes in meteorological features of the french coast area during the last half-century - examples of 2 biological responses
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Ibanez, F.
Chronological series (1949 to 1992) of air temperature, precipitation, atmospheric pressure and wind in different parts of the French coast show evidence of important year-to-year changes, trends and cycles: seven-eight years for temperature, and around three years for precipitation and atmospheric pressure. On the scale of France, it appears that spatial heterogeneity of meteorological factors is smaller than temporal heterogeneity. New methods, such as the cumulative sums method or the envelopes of a variable reveal the interest for ecologists of essaying different numerical approaches. A comparison between climatic series and biological series of a benthic and a pelagic species is described for this purpose.
Tipo: Text
Palavras-chave: METEOROLOGICAL SERIES; BIOLOGICAL SERIES; TRENDS; CYCLES; CHANGES.
Ano: 1994
URL: http://archimer.ifremer.fr/doc/00098/20891/18505.pdf

An evaluation of changes in stock productivity and consequences for management. An example based on North Atlantic albacore Thunnus alalunga
Provedor de dados: 5
Autores: Kell, Laurence T; Fromentin, Jean-marc.
Reference points are important elements of fisheries management and the supporting scientific advisory frameworks. However, fish stocks can fluctuate extensively over a large range of spatial and temporal scales independent of human exploitation and there has been a classical tendency to assume a dichotomy, i.e., that changes in fish populations are primarily attributable either to exploitation or to environmental variability. Therefore we look at variability in surplus production and examine the relative impacts of the environment and exploitation on the productivity of North Atlantic albacore (Thunnus alalunga). The analysis revealed that variations were driven by environmental effects. It was also found that substantial variations in time-series of...
Tipo: Text
Palavras-chave: Thunnus alalunga; Albacore; Fisheries management; FLR; Reference points; Stationary processes; Surplus production.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00192/30282/28758.pdf

Effects of biological, economic and management factors on tuna and billfish stock status
Provedor de dados: 5
Autores: Pons, Maite; Branch, Trevor A.; Melnychuk, Michael C.; Jensen, Olaf P.; Brodziak, Jon; Fromentin, Jean-marc; Harley, Shelton J.; Haynie, Alan C.; Kell, Laurie T.; Maunder, Mark N.; Parma, Ana M.; Restrepo, Victor R.; Sharma, Rishi; Ahrens, Robert; Hilborn, Ray.
Commercial tunas and billfishes (swordfish, marlins and sailfish) provide considerable catches and income in both developed and developing countries. These stocks vary in status from lightly exploited to rebuilding to severely depleted. Previous studies suggested that this variability could result from differences in life-history characteristics and economic incentives, but differences in exploitation histories and management measures also have a strong effect on current stock status. Although the status (biomass and fishing mortality rate) of major tuna and billfish stocks is well documented, the effect of these diverse factors on current stock status and the effect of management measures in rebuilding stocks have not been analysed at the global level....
Tipo: Text
Palavras-chave: Fisheries management; Marine conservation; Stock assessment; Stock status; Tuna fisheries.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00333/44383/44107.pdf

Standardized CPUE of bluefin tuna (Thunnus thynnus) caught by spanish traps for the period 1981-2004
Provedor de dados: 5
Autores: Ortiz De Urbina, J; Fromentin, Jean-marc; Restrepo, Victor R; Arrizabalaga, Haritz; De La Serna, Jose-miguel.
Catch rates from the Spanish traps in the Atlantic have been traditionally standardized using a GLM approach with a lognormal error assumption. Nevertheless, some concerns have been expressed regarding the current unit of effort used for standardization purposes as well as the model error assumption. This document explores the adequacy of current effort unit and proposes alternative model error assumptions for the standardization of the CPUE index.
Tipo: Text
Ano: 2007
URL: http://archimer.ifremer.fr/doc/00192/30298/28788.pdf

The spectre of uncertainty in management of exploited fish stocks: The illustrative case of Atlantic bluefin tuna
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain; Arrizabalaga, Haritz; Kell, Laurence T.
The recent overexploitation of East Atlantic and Mediterranean bluefin tuna stock has been well documented in the media where it has become the archetype of overfishing and general mis-management. Beyond the public debate, the crisis also highlighted how the interactions between science and management can change through time according to the awareness of the public opinion. To reflect these issues, the history of Atlantic bluefin tuna overfishing is first described. Then, the major uncertainties that undermine the current scientific advice are summarized and the importance of reducing their impacts by improving knowledge and developing robust scientific framework is considered. The study also discusses how uncertainty was used by different lobbies to...
Tipo: Text
Palavras-chave: Overexploitation; Rebuilding; Uncertainty; Management; Scientific diagnosis; Tuna.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00177/28776/27302.pdf

Can stochastic variations in recruitment induce long-term fluctuations in the carrying capacity?
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
Long-term fluctuations in fish abundance are generally attributed to low frequency processes, such as human exploitation and/or environmental and climatic changes. Based on recent studies and simple simulations, this manuscript shows how long-term fluctuations in the carrying capacity and/or spawning stock biomass of a long-live species, such as the Atlantic bluefin tuna, may simply arise from stochastic variations in the recruitment. The implications of such a feature are discussed and compared among different Atlantic tunas and tuna-like species.
Tipo: Text
Palavras-chave: Long-term fluctuations; Recruitment; Atlantic tunas; Stochastic variations; Life history; Lifespan; Spawning stock biomass.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00194/30499/28909.pdf

Estimates of total mortality of eastern Atlantic bluefin tuna based on year-class curves
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Arrizabalaga, Haritz; Restrepo, Victor R; Ortiz De Urbina, J.
The 2004 data exploratory meeting concluded that it was no longer defensible to assess the East Atlantic and Mediterranean population using methods that assume that the catch-atsize/age is known exactly, until extensive improvements in fisheries statistics are made. For these reasons, we here investigated the potential benefits of the year-class curve analysis. The robustness and consistency of our results tend to advocate that this method is, in the present situation, a good alternative to ADAPT (among others). As a whole, the estimates of Z from the year-class curve analyses applied on the Spanish trap and Japanese long line fishery data appear indeed to be in good or excellent agreement with ADAPT outputs for the same period and same age-classes. This...
Tipo: Text
Palavras-chave: Fishing and natural mortalities; Year-class curves; Stock assessment.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/00192/30325/28799.pdf

Gestion écosystémique de la pêche et de l’aquaculture. La gestion du thon rouge : histoire de la surexploitation et de son rétablissement
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Rouyer, Tristan.
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00487/59824/62967.pdf

Length based catch analysis for east Atlantic Mediterranean bluefin tuna
Provedor de dados: 5
Autores: Kell, Laurence T; Bonhommeau, Sylvain; Fromentin, Jean-marc.
Although the bluefin assessment is based on catch-at-age data, ageing using hard parts is an expensive and d{fficult process. Therefore length data are converted into age for bluefin using a growth curve, i.e. age slicing. Where age is predicted from length using the inverse of the von Bertalanffy growth curve. Here we show how a simple method based on length data alone can be used to estimate population parameters such as total mortality (Z).
Tipo: Text
Palavras-chave: Bluefin; Catch curve analysis; Growth; Length; Mortality.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00191/30274/28734.pdf

Determining bluefin tuna habitat through frontal features in the Mediterranean sea
Provedor de dados: 5
Autores: Royer, Francois; Fromentin, Jean-marc; Farrugio, Henri; Gaspar, Philippe.
The distribution patterns of bluefin tuna schools observed during the STROMBOLI EU project (2000-2002) were analysed in relation to oceanographic conditions. High-resolution radiometers (AVHRR and SeaWiFS) were used on a daily basis to derive maps of environmental variability. An edge detection technique was especially applied to estimate the position of frontal features. Using a variety of geostatistical and point process techniques, we were able to show that the distribution of bluefin schools was partially driven by the occurrence of transient fronts in the Gulf of Lions. This is believed to be mainly a trophic association, since enhanced convergence and retention processes occur at fronts, possibly leading to higher prey densities (e.g. anchovies). The...
Tipo: Text
Palavras-chave: Thunnus thynnus; Aerial survey; Gulf of Lions; Sea surface temperature; Ocean colour; Fronts.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00194/30504/28914.pdf

Populations ichtyologiques de grands pélagiques. Sous-région marine Manche - Mer du Nord. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain.
Tipo: Text
Palavras-chave: Manche; Mer du Nord; Grands poissons pélagiques; Biocénose; Exploitation; Etat des stocks.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00327/43844/43418.pdf

Trophic ecology of the European Hake in the Gulf of Lions, Northwestern Mediterranean Sea
Provedor de dados: 5
Autores: Mellon, Capucine; Harmelin-vivien, Mireille; Metral, Luisa; Loizeau, Veronique; Mortreux, Serge; Roos, David; Fromentin, Jean-marc.
The European hake, Merluccius merluccius, is an important resource for Mediterranean fisheries. This study focuses on juvenile and adult hake feeding ecology in the Gulf of Lions, using information from scientific surveys carried out during two seasons and three years (2004-2006). Stomach content and stable isotope (ä15N, ä13C) analyses were performed, and the main factors explaining variations in ä15N were investigated using GLMs. In the Gulf of Lions, hake mostly fed on crustaceans and fish and a dominant piscivorous regime was reached at 15 cm total length. Pelagic fish (sardine, anchovy and small blue whiting) were the main source of prey (40%-80%) and cannibalism was low (&lt;5%). The results confirmed that hake is an opportunistic feeder and also...
Tipo: Text
Palavras-chave: Foodweb; GLM; Habitat; Merluccius merluccius; Predator-prey relationships; Stable isotopes; Stomach contents.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00360/47091/47016.pdf

Dynamics of the Norwegian Skagerrak cod: intuition vs inference
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bjornstad, On; Stenseth, Nc; Gjosaeter, J.
Tipo: Text
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00000/10045/7599.pdf

Biological reference points and natural long-term fluctuations: the case of eastern Atlantic bluefin tuna
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Fonteneau, Alain; Farrugio, Henri.
Defining biological key reference points is of importance within the precautionary approach. Most of the reference points, such as the FMSY, Fo.], presuppose a steady state, i.e. the natural long-term fluctuations of the population are low or moderate. In this manuscript, we present historical data from Sicilian, Sardinian, Portuguese, and Tunisian traps of the Atlantic bluefin tuna during 200 to 400 years. Long-term fluctuations in trap data could be considered as a good proxy for long-term trend in true abundance because trap is a passive gear which was submitted to low modification until the XX century and because data from different areas display similar long-term variations. Trends in trap data appear beIl shaped, with a maximum at the end ofthe XIXth...
Tipo: Text
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00194/30485/28890.pdf

Estimates of selectivity for eastern Atlantic bluefin tuna from catch curves
Provedor de dados: 5
Autores: Restrepo, Victor R; Ortiz De Urbina, J; Fromentin, Jean-marc; Arrizabalaga, Haritz.
Knowledge of gear-specific selectivity patterns can be useful in age-structured analyses. In recent assessments of eastern Atlantic bluefin tuna, Thunnus thynnus, the SCRS has derived selectivity estimates from the results of virtual population analyses. This document proposes an alternative approach, based on equilibrium catch curves, that is simple to apply and that relies on a smaller set of assumptions. The study uses the catch-at-age data from the last assessment conducted in 2002, and estimates recent and historical selectivity patterns for the total stock as well as some of the major gears (trap, baitboat, purse seine and longline). The resulting estimates seem reasonable for the various gears, given prior knowledge. The document also presents...
Tipo: Text
Palavras-chave: Gear selectivity; Stock assessment; Bluefin tuna.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/00192/30326/28800.pdf

Global habitat preferences of commercially valuable tuna
Provedor de dados: 5
Autores: Arrizabalaga, Haritz; Dufour, Florence; Kell, Laurence; Merino, Gorka; Ibaibarriaga, Leire; Chust, Guillem; Irigoien, Xabier; Santiago, Jose Luis; Murua, Hilario; Fraile, Igaratza; Chifflet, Marina; Goikoetxea, Nerea; Sagarminaga, Yolanda; Aumont, Olivier; Bopp, Laurent; Herrera, Miguel; Fromentin, Jean-marc; Bonhomeau, Sylvain.
In spite of its pivotal role in future implementations of the Ecosystem Approach to Fisheries Management, current knowledge about tuna habitat preferences remains fragmented and heterogeneous, because it relies mainly on regional or local studies that have used a variety of approaches making them difficult to combine. Therefore in this study we analyse data from six tuna species in the Pacific, Atlantic and Indian Oceans in order to provide a global, comparative perspective of habitat preferences. These data are longline catch per unit effort from 1958 to2007 for albacore, Atlantic bluefin, southern bluefin, bigeye, yellowfin and skipjack tunas. Both quotient analysis and Generalized Additive Models were used to determine habitat preference with respect to...
Tipo: Text
Palavras-chave: Habitat; Tuna fisheries; Catch/effort; Environmental conditions; Quotient analysis; Generalised Additive Models; Ecosystem Approach to Fisheries Management.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00201/31190/29589.pdf

A state-space model to derive bluefin tuna movement and habitat from archival tags
Provedor de dados: 5
Autores: Royer, Francois; Fromentin, Jean-marc; Gaspar, P.
Archival tagging provides a unique way to study the spatial dynamics and habitat of pelagic fish. This technique generates lagrangian data of a particular type in marine ecology: although highly informative about processes at different scales (e.g. horizontal movements versus diving behaviour), such data are impaired by location errors and the lack of combination with actual environmental variability. The present paper introduces a framework for modelling bluefin tuna movement in relation to its habitat, using records of light, depth and temperature from archival tags. Based on data assimilation concepts and methods, we show how an explicit formulation of the observation process and the statistics of external variables (e.g. ambient temperature) can...
Tipo: Text
Palavras-chave: Tag; Archival; Habitat; Movement; Bluefin tuna.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/publication-671.pdf

Large-scale spatio-temporal monitoring highlights hotspots of demersal fish diversity in the Mediterranean Sea
Provedor de dados: 5
Autores: Granger, Victoria; Fromentin, Jean-marc; Bez, Nicolas; Relini, Giulio; Meynard, Christine N.; Gaertner, Jean-claude; Maiorano, Porzia; Garcia Ruiz, Cristina; Follesa, Cristina; Gristina, Michele; Peristeraki, Panagiota; Brind'Amour, Anik; Carbonara, Pierluigi; Charilaou, Charis; Esteban, Antonio; Jadaud, Angelique; Joksimovic, Aleksandar; Kallianiotis, Argyris; Kolitari, Jerina; Manfredi, Chiara; Massuti, Enric; Mifsud, Roberta; Quetglas, Antoni; Refes, Wahid; Sbrana, Mario; Vrgoc, Nedo; Spedicato, Maria Teresa; Merigot, Bastien.
Increasing human pressures and global environmental change may severely affect the diversity of species assemblages and associated ecosystem services. Despite the recent interest in phylogenetic and functional diversity, our knowledge on large spatio-temporal patterns of demersal fish diversity sampled by trawling remains still incomplete, notably in the Mediterranean Sea, one of the most threatened marine regions of the world. We investigated large spatio-temporal diversity patterns by analysing a dataset of 19,886 hauls from 10 to 800 m depth performed annually during the last two decades by standardized scientific bottom trawl field surveys across the Mediterranean Sea, within the MEDITS program. A multi-component (eight diversity indices) and...
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00216/32743/31322.pdf

Biogeography of tuna and billfish communities
Provedor de dados: 5
Autores: Reygondeau, Gabriel; Maury, Olivier; Beaugrand, Gregory; Fromentin, Jean-marc; Fonteneau, Alain; Cury, Philippe.
Aim The aims of this study were: (1) to identify global communities of tuna and billfish species through quantitative statistical analyses of global fisheries data; (2) to describe the spatial distribution, main environmental drivers and species composition of each community detected; and (3) to determine whether the spatial distribution of each community could be linked to the environmental conditions that affect lower trophic levels by comparing the partitions identified in this study with Longhursts biogeochemical provinces. Location The global ocean from 60 degrees S to 65 degrees N. Methods We implemented a new numerical procedure based on a hierarchical clustering method and a nonparametric probabilistic test to divide the oceanic biosphere into...
Tipo: Text
Palavras-chave: Biogeochemical provinces; Global ocean; Istiophorus; Katsuwonus; Macroecology; Makaira; Marine biogeography; Tetrapturus; Thunnus; Xiphias.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00060/17141/14716.pdf

Tagging bluefin tuna in the Mediterranean sea: challenge or mission: impossible?
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
Since 2007, Ifremer together with the French Federation of Sport fishermen (FFPM) and Big Game Fishing Club France (BGFCF) have been carrying out a program of conventional and electronic tagging on bluefin tuna in the western Mediterranean Sea. 479 and 95 ICCAT “spaghetti” tags have been deployed by the FFPM recreational and sportive fishermen along the Mediterranean French coasts in 2007 and 2008, respectively. To date, not a single  recapture has been registered. Ifremer together with BGFCF has deployed 11, 6 and 8 pop-up archival tags (PAT) offshore of Marseille in 2007, 2008 and 2009, respectively. Outputs were impaired by two main technical difficulties: premature detachment and low transmission rates in the Argos band over the Mediterranean. While...
Tipo: Text
Palavras-chave: Thunnus thynnus; Tagging; Mediterranean Sea; Pop-up archival tag; Conventional tag.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00192/30291/28770.pdf

Determining natal origin for improved management of Atlantic bluefin tuna
Provedor de dados: 5
Autores: Rodríguez‐ezpeleta, Naiara; Díaz‐arce, Natalia; Walter, John F; Richardson, David E; Rooker, Jay R; Nøttestad, Leif; Hanke, Alex R; Franks, James S; Deguara, Simeon; Lauretta, Matthew V; Addis, Piero; Varela, Jose Luis; Fraile, Igaratza; Goñi, Nicolas; Abid, Noureddine; Alemany, Francisco; Oray, Isik K; Quattro, Joseph M; Sow, Fambaye N; Itoh, Tomoyuki; Karakulak, F Saadet; Pascual‐alayón, Pedro J; Santos, Miguel N; Tsukahara, Yohei; Lutcavage, Molly; Fromentin, Jean-marc; Arrizabalaga, Haritz.
Effective sustainable management of marine fisheries requires that assessed management units (that is, fish stocks) correspond to biological populations. This issue has long been discussed in the context of Atlantic bluefin tuna (ABFT, Thunnus thynnus) management, which currently considers two unmixed stocks but does not take into account how individuals born in each of the two main spawning grounds (Gulf of Mexico and Mediterranean Sea) mix in feeding aggregations throughout the Atlantic Ocean. Using thousands of genome‐wide molecular markers obtained from larvae and young of the year collected at the species’ main spawning grounds, we provide what is, to the best of our knowledge, the first direct genetic evidence for “natal homing” in ABFT. This has...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00595/70710/68917.pdf

Hydroclimatic relationships with planktonic time series from 1975 to 1992 in the North Sea off Gravelines, France
Provedor de dados: 5
Autores: Le Fevre-lehoerff, Geneviève; Ibanez, Frédéric; Poniz, Paola; Fromentin, Jean-marc.
Planktonic time series collected since 1975 off Gravelines, France, were analysed in the context of climatic changes. Principal component analysis and the cumulative sums method wereapplied to 30 data sets which included meteorological and hydrological parameters and planktonic descriptors. Eight groups of biological descriptors were linked to external parameters. The study of winds highlighted the importance of cyclonic and anticyclonic influences. Seven year cycles appeared clearly in air temperature and in species abundance with different trophic levels for species such as Ternora longicornis, Oikopleura dioica and Sagitta setosa, whereas an 11 yr cycle appeared for Pseudocalanus minutus. A 3 to 4 yr cycle was detected for atmospheric pressure,...
Tipo: Text
Palavras-chave: Time series; Zooplankton; Meteorology; Hydrology; Southern North Sea.
Ano: 1995
URL: http://archimer.ifremer.fr/doc/00033/14455/11757.pdf

Environmental noise in spawning areas: the case of Atlantic bluefin tuna (Thunnus thynnus)
Provedor de dados: 5
Autores: Royer, Francois; Fromentin, Jean-marc.
This paper provides an exploratory analysis aiming to seek whether the colour of environmental noise theory could help in understanding the intriguing reproductive strategy of Atlantic bluefin tuna (BFT). A frequency-based approach based on spectral exponents, f(beta) with beta &lt; 0, is chosen and applied on 10 biogeographical provinces covering the North Atlantic. The major BFT spawning area, i.e. the Mediterranean Sea, was the only one to display a pink power spectrum, whereas open ocean regions displayed more reddened fluctuations, i.e. greater variance at low frequencies. Environmental noise in the Mediterranean could, thus, offer more favourable characteristics on the long-term than the open ocean. The implications of these findings are discussed in...
Tipo: Text
Palavras-chave: Thunnus thynnus; Spectral analysis; Spawning; Sea surface temperature; Environmental noise.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2437.pdf

A year-class curve analysis to estimate mortality of Atlantic bluefin tuna caught by the Norwegian fishery from 1956 to 1979
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Restrepo, Victor.
At the ICCAT symposium on bluefin tuna that held in Santander in April 2008, Tangen et al.(2009) presented a first quantification of the fishing effort deployed by the Norwegian fishery targeting bluefin tuna in the North Sea and Norwegian Sea. Using a year-class curve analysis on the Norwegian CPUE, this document presents the first estimates of mortality rates of Atlantic bluefin tuna that migrated north from the mid-1950s to the late 1970s. The results indicate that bluefin tuna would have experienced a total mortality rate (Z) of 0.2 to 0.4 yr-1 (i.e. F at around 0.3 yr-1) during the late 1950s, 0.2 yr-1 during the 1960s and 0.1 yr-1 afterwards (assuming M=0.1 yr-1). These results appear to be rather robust and consistent with the VPA estimates from the...
Tipo: Text
Palavras-chave: Thunnus thynnus; Fishing and natural mortalities; Year-class curves; Stock assessment.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00192/30294/28783.pdf

L'approche écosystémique des pêches : quelles priorités pour la recherche ?
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Planque, Benjamin; Thebaud, Olivier.
This document discusses the possible evolutions of IFREMER's research activities in support of the ecosystem-based approach to fisheries management (EAF). It results from an investigation undertaken within the programme "Ecosystem approach to the management of fish resources" (DÉMarche écOSysTÉMique pour une gestion des Ressources Halieutiques").  The first part of the document presents the background to the development of the EAF, particularly the increasing number of reports of resource over-exploitation, the issue of sustainability of exploitation systems, the diversification of uses of marine resources, the key role of governance and the degradation of the state of the ecosystems.  The second part aims at synthesizing the challenges faced by research...
Tipo: Text
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/rapport-2567.pdf

Ecosystem approach to fisheries: a brief overview and some considerations for its application in ICCAT
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Fonteneau, Alain; Restrepo, Victor.
During the last SCRS plenary meeting, the sub-committee on environment suggested to present a document on the ‘Ecosystem Approach to Fisheries’ (EAF). This document firstly recalls the general scientific and institutional background of EAF, then we propose a synoptic view of EAF, including four main domains: governance, exploitation, resources and impacts on ecosystems. The way that EAF is tackled within the various tuna commissions is then summarised. Finally, we rapidly examine the way the SCRS could cope with EAF issues and we suggest to merge the sub-committee on environment with this on by-catch into a single subcommittee on ecosystem.
Tipo: Text
Palavras-chave: Ecosystem; Resources; Exploitation; Governance; Environment; By-catch.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/00192/30334/28809.pdf

Effects of density-dependent and stochastic processes on the regulation of cod populations
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Myers, Ransom; Bjornstad, Ottar; Stenseth, Nils; Gjosaeter, Jakob; Christie, Hartvig.
We analyzed 136 time series (covering from 44 to 73 yr) of juvenile cod to estimate the level of direct and delayed density-dependent mortality (DDM) of 11 populations from the Norwegian Skagerrak coast. The parameters were estimated using a modeling approach that explicitly incorporates observation errors, so that we could quantify the density-independent (stochastic) variation in the survival of juvenile cod. Moderate to strong levels of DDM (direct or delayed) were estimated in eight of the 11 populations. Variability in the 0-group (corrected for observation errors) appeared to be large for most of the populations. Substantial stochastic variability in postsettlement survival was also detected in some areas, indicating that stochastic factors are not...
Tipo: Text
Palavras-chave: Stochastic survival; Juvenile Observation errors Mortality; Direct density dependent Mortality; Delayed density dependent Gadus morhua Fjord Cod population dynamics Bottom flora coverage.
Ano: 2001
URL: https://archimer.ifremer.fr/doc/2001/publication-712.pdf

Association between bluefin tuna schools and oceanic features in the western Mediterranean
Provedor de dados: 5
Autores: Royer, Francois; Fromentin, Jean-marc; Gaspar, P.
We present an analysis of the distribution of bluefin tuna Thunnus thynnus schools spotted during aerial surveys in the Gulf of Lions, in relation to oceanographic features. Bio-optical and thermal properties of the sea surface derived from high-resolution sensors (AVHRR and SeaWiFS) were studied on a daily basis, and an edge-detection technique was applied to detect frontal zones. Geostatistics and point-process analyses were used to evaluate the role of the environment in structuring the spatial pattern of bluefin tuna (BFT). The distribution of schools spotted was strongly non-stationary both in space and time; this is believed to be an effect of the survey design (transect sampling) and the influence of transient oceanographic structures (surface...
Tipo: Text
Palavras-chave: Thunnus thynnus; Gulf of Lions; Point process analysis; Front detection; Sea surface temperature; Ocean colour; Aggregation.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/00000/10786/7585.pdf

Is the recruitment a key biological process in the hypothetical NAO-Atlantic tunas relationships?
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
In the recent past, it has been put forward that recruitment of the North Atlantic albacore, East Atlantic bluefin tuna and North Atlantic swordfish could be related to the North AtlanticOscillation (NAO). In this document, the biological processes behind the NAO/recruitmentrelationship are further investigated. Then, the possible relationship between the East Atlanticbluefin tuna recruitment was re-investigated. The linear relationship appeared to be only due to the low frequency signal, both BFT recruitment and NAO displaying a pseudo-cyclic upwardtrend, but year-to-year fluctuations were not synchronous. The superposed epoch analysis, thatwas conducted to test for possible non-linear and non-monotonous relationship did not reveal any clear connection....
Tipo: Text
Palavras-chave: North Atlantic Oscillation; Recruitment; Bluefin; Albacore; Swordfish; Migration patterns; Time series; Spatially disaggregated data.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00194/30498/28908.pdf

Bluefin tuna stock assessment in the northeast Atlantic: difficulties related to data, methods and knowledge
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
The robustness of ADAPT conceming the 1996 SCRS bluefin tuna stock assessment for the northeast Atlantic is tested through various sensitivity analyses on the main technical specifications. We aIso computed simple VPA in order to investigate the reIiability of the trends in the recruitment estimates and the stock estimates of ages 2-5 and 8+. It is concluded that: (i) the estimates of the 1996 SCRS working group are very sensitive to the technical specifications on the F-ratios (which determine F for the last group), natural mortality as well as to under-reporting on the catch data; and (ii) the increasing trends of the recruitment and the young ages as well as the strong decline in ages 8 + should be treated with caution.
Tipo: Text
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00194/30556/28972.pdf

Evaluation of the robustness of maximum sustainable yield based management strategies to variations in carrying capacity or migration pattern of Atlantic bluefin tuna (Thunnus thynnus)
Provedor de dados: 5
Autores: Kell, L; Fromentin, Jean-marc.
In this study, we examine the performances of current stock assessment methods with respect to their ability to (i) provide estimates of maximum sustainable yield (MSY), FMSY, and BMSY and (ii) assess stock status and exploitation level relative to MSY targets. The robustness of the current International Commission for the Conservation of Atlantic Tunas (ICCAT) management strategy is then evaluated with respect to uncertainty about the true population dynamics and contrasted with a simpler management strategy based solely on a size limit. Reference points are more robust to dynamic uncertainty than the estimates of absolute values and trends in F and spawning stock biomass. However, their performances depend on the underlying dynamics (they perform better...
Tipo: Text
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2006/publication-3534.pdf

Aerial surveys to monitor bluefin tuna abundance and track efficiency of management measures
Provedor de dados: 5
Autores: Bauer, Robert; Bonhommeau, Sylvain; Brisset, Blandine; Fromentin, Jean-marc.
Conservation and management measures for exploited fish species rely on our ability to monitor variations in population abundance. In the case of the eastern stock of Atlantic bluefin tuna (ABFT), recent changes in management policies have strongly affected the reliability of fishery-dependent indicators due to drastic changes in fishing season/area, fisheries selectivity and strategy. However, fishery-independent indices of abundance are rare for large pelagic fish, and obtaining them is often costly and labor intensive. Here, we show that scientific aerial surveys are an appropriate tool for monitoring juvenile bluefin tuna abundance in the Mediterranean. We present an abundance index based on 62 aerial surveys conducted since 2000, using 2 statistical...
Tipo: Text
Palavras-chave: Thunnus thynnus; Index of abundance; Fishery-independent; Gulf of Lions; Mediterranean Sea; Strip transect; Distance sampling.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00281/39192/45096.pdf

Calanus and environment in the eastern North Atlantic. 2. Role of the North Atlantic Oscillation on Calanus finmarchicus and C. helgolandicus
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Planque, Benjamin.
The influence of the North Atlantic Oscillation (NAO) on 2 major zooplankton species ofthe eastern North Atlantic and the North Sea, Calanus finmarchicus and C. helgolandicus (Copepoda, Calanoida), was investigated. Our results confirm that from December to April, west wind stress (WWS) intensity and temperature are strongly related to the NAO. If these results were expected, more striking were the close relationships between NAO and Calanus species abundance. Fluctuations in abundance of C. finmarchicus mainly result from the combination of 2 factors, both driven by the NAO: WWS effects on spring primary production and temperature. The case of C. helgolandicus is more complicated,as the links between this species and the NAO result from the combination of...
Tipo: Text
Ano: 1996
URL: http://archimer.ifremer.fr/doc/00033/14456/11758.pdf

Populations ichtyologiques des grands pélagiques. Sous-région marine Méditerranée occidentale. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain.
Tipo: Text
Palavras-chave: Méditerranée; Grands poissons pélagiques; Biocénose; Exploitation; Etat des stocks.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00331/44213/43782.pdf

Une typologie à partir de la forme des séries chronologiques (TFS)
Provedor de dados: 5
Autores: Ibanez, F; Fromentin, Jean-marc.
The typology of shapes of series (TSS) aims to gather together species having similar temporal patterns corresponding to different types of ecological behaviour. Each type of change, referred to as the ecological shape, is considered to reflect a particular demographic strategy (sudden pullulation of opportunistic species, fluctuations with environmental changes, etc.). This method which consists in the definition of four shape parameters and a classification among the series, taking into account these shape parameters, does not replace the usual statistical analyses, mainly multivariate ones, but precedes them. Such preliminary information is useful for the choice of the subsequent treatments, avoiding the need to analyse simultaneously species presenting...
Tipo: Text
Palavras-chave: Times series; Ecological shape; Macrobenthic community; English Channel.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00093/20384/18050.pdf

Trophic structure in the Gulf of Lions marine ecosystem (north-western Mediterranean Sea) and fishing impacts
Provedor de dados: 5
Autores: Banaru, Daniela; Mellon, Capucine; Roos, David; Bigot, Jean-louis; Souplet, Arnauld; Jadaud, Angelique; Beaubrun, P.; Fromentin, Jean-marc.
The Gulf of Lions ecosystemwas described using the Ecopath mass-balancemodel to characterise its structure and functioning and to examine the effects of themultispecific fisheries operating in this area. The model is composed of 40 compartments, including 1 group of seabirds, 2 groups of etaceans, 18 groups of fish, 12 groups of invertebrates, 5 groups of primary producers, detritus and discards. Input datawere based on several recurrent scientific surveys, two alternative datasets for fishing data, stock assessment outputs, stomach content analyses and published information. Results showed that the functional groups were organised into five trophic levels with the highest one represented by dolphins, anglerfish, Atlantic bluefin tuna, European hake and...
Tipo: Text
Palavras-chave: Gulf of Lions; Ecopath with Ecosim; Food web; Fishing impacts.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00116/22758/20614.pdf

Satellite-based indicator of zooplankton distribution for global monitoring
Provedor de dados: 5
Autores: Druon, Jean-noel; Helaouet, Pierre; Beaugrand, Grégory; Fromentin, Jean-marc; Palialekis, Andreas; Hoepffner, Nicolas.
This study investigates the association between an index of mesozooplankton biomass, derived from the Continuous Plankton Recorder survey and satellite-derived productivity fronts in the North Atlantic. While chlorophyll-a content (CHL) is commonly described as a proxy for phytoplankton biomass, the size of productivity fronts estimated from the horizontal gradient of CHL appears to be directly linked to mesozooplankton biomass. Our results suggest that the lifespan of productivity fronts, which ranges from weeks to months, meets the time requirement of mesozooplankton to develop. The proposed indicator describes the daily distribution of mesozooplankton’s suitable feeding habitat. It also provides a coherent interpretation of the productivity front...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00486/59744/62843.pdf

Patterns of variations in large pelagic fish: A comparative approach between the Indian and the Atlantic Oceans
Provedor de dados: 5
Autores: Corbineau, A.; Rouyer, Tristan; Fromentin, Jean-marc; Cazelles, B.; Fonteneau, Alain; Menard, Frederic.
Catch data of large pelagic fish such as tuna, swordfish and billfish are highly variable ranging from short to long term. Based on fisheries data, these time series are noisy and reflect mixed information on exploitation (targeting, strategy, fishing power), population dynamics (recruitment, growth, mortality, migration, etc.), and environmental forcing (local conditions or dominant climate patterns). In this work, we investigated patterns of variation of large pelagic fish (i.e. yellowfin tuna, bigeye tuna, swordfish and blue marlin) in Japanese longliners catch data from 1960 to 2004. We performed wavelet analyses on the yearly time series of each fish species in each biogeographic province of the tropical Indian and Atlantic Oceans. In addition, we...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00011/12231/9029.pdf

Habitat use, vertical and horizontal behaviour of Atlantic bluefin tuna ( Thunnus thynnus ) in the Northwestern Mediterranean Sea in relation to oceanographic conditions
Provedor de dados: 5
Autores: Bauer, Robert Klaus; Fromentin, Jean-marc; Demarcq, Herve; Bonhommeau, Sylvain.
We investigated the habitat utilization, vertical and horizontal behaviour of Atlantic bluefin tuna Thunnus thynnus (ABFT) in relation to oceanographic conditions in the northwestern Mediterranean Sea, based on 36 pop-up archival tags and different environmental data sets. Tags were deployed on early mature ABFT (127–255 cm) between July and November in 2007-2014, on the shelf area off Marseille, France. The data obtained from these tags provided 1643 daily summaries of ABFT vertical behaviour over 8 years of tag deployment. Based on a hierarchical clustering of this data, we could identify four principle daily vertical behaviour types, representing surface (≦10m) and subsurface (10–100 m) orientation, moderate (50–200 m) and deep (≧200m) diving behaviour....
Tipo: Text
Palavras-chave: Thunnus thynnus; Habitat use; Spike dives; Fronts; Thermal stratification; Archival tags.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00382/49329/49709.pdf

Linking small pelagic dietary shifts with ecosystem changes in the Gulf of Lions
Provedor de dados: 5
Autores: Brosset, Pablo; Le Bourg, Baptiste; Costalago, David; Banaru, Daniela; Van Beveren, Elisabeth; Bourdeix, Jean-herve; Fromentin, Jean-marc; Menard, Frederic; Saraux, Claire.
Since 2008, a severe decrease in size and body condition together with a demographic truncation has been observed in the sardine (secondarily in anchovy) population of the Gulf of Lions (NW Mediterranean Sea). In parallel, sprat biomass, which was negligible before, has increased tenfold. All of these changes have strongly affected the regional fisheries. Using trophic and isotopic data from contrasting periods of low versus high growth and condition, we investigated potential changes in diet and interspecific feeding interactions through time. Evidence of resource partitioning was found between sprat and both anchovy and sardine in 2004 and 2005. Since 2010, the isotopic niches of the 3 species have tended to overlap, suggesting higher risk of competition...
Tipo: Text
Palavras-chave: Trophic ecology; Anchovy; Sardine; Sprat; Dietary overlap; NW Mediterranean.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00347/45822/45540.pdf

Analysis of the potential impact of several management measures for eastern Atlantic bluefin tuna on the basis of yield per recruit
Provedor de dados: 5
Autores: Arrizabalaga, Haritz; Restrepo, Victor; Fromentin, Jean-marc; Ortiz De Urbina, J M.
A standard yield per recruit (YPR) analysis is used to analyse the effects of minimum size regulations and time area closures on bluefin tuna from the eastern stock (east Atlantic and Mediterranean). Analyses were based on a fishing mortality vector computed over the period 1990-1994 for which data were more reliable and VPA (performed during the 2002 stock assessment) showed a relatively good convergence. This fishing mortality vector was modified according to some combinations of minimum size regulations and time area closures. It is concluded that: (i) PSmed is the main contributor to catch at age in the range of ages 1-13; (ii) The minimum size regulations considered would increase the YPR more than the time area closures, but these would enhance SPR...
Tipo: Text
Palavras-chave: Yield/recruit; Yield predictions; Size limit regulations; Time-area closures; Bluefin tuna.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/00192/30329/28806.pdf

Lessons from the past: investigating historical data from bluefin tuna fisheries
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
In 1963, the leading fisheries targeting Atlantic bluefin tuna (Thunnus thynnus) in the Norwegian Sea and North Sea suddenly collapsed without any warning. Little is known about this collapse and several hypotheses have been put forward, such as changes in migratory routes, recruitment failure or eradication of a sub-population: all of these hypotheses could result from natural causes and/or from overfishing. To help explain this mysterious event, an original data set of the main bluefin tuna fisheries of the 20th century, including total catch and size composition of the catch, has been compiled and analysed. The results reveal a strong and unambiguous link between the Nordic purse seine and Spanish trap fisheries during the 1950s and 1960s. However, this...
Tipo: Text
Palavras-chave: Thunnus thynnus; Retrospective analysis; Population structure; Migration patterns; Fisheries collapse.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6425.pdf

Evaluation of the performance and robustness of VPA-based stock assessment and MSY-based management strategy to process error: the Atlantic bluefin tuna case study
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Kell, Laurence T.
An integrative simulation framework was built to evaluate the consequences of variability attributable to changes in carrying capacity or the stock’s migration pattern of Atlantic bluefin tuna on the ICCAT stock assessment and management procedures. We also evaluated the performances of stock assessment methods with respect to their ability to provide good estimates of MSY, FMSY and BMSY and tested the robustness of the current ICCAT management strategy to uncertainty about the true dynamics and historical exploitation levels. The results clearly indicate that the VPA performances were seriously impaired if the long-term variations in catches are due to changes in migration/availability. There is further considerable confounding between the underlying...
Tipo: Text
Palavras-chave: Thunnus thynnus; Stock assessment; VPA; Biological reference points; MSY; Management strategy; Simulation model.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00192/30295/28786.pdf

Mapping diversity indices: not a trivial issue
Provedor de dados: 5
Autores: Granger, Victoria; Bez, Nicolas; Fromentin, Jean-marc; Meynard, Christine; Jadaud, Angelique; Merigot, Bastien.
Mapping diversity indices, that is estimating values in all locations of a given area from some sampled locations, is central to numerous research and applied fields in ecology.   Two approaches are used to map diversity indices without including abiotic or biotic variables: (i) the indirect approach, which consists in estimating each individual species distribution over the area, then stacking the distributions of all species to estimate and map a posteriori the diversity index, (ii) the direct approach, which relies on computing a diversity index in each sampled locations and then to interpolate these values to all locations of the studied area for mapping.   For both approaches, we document drawbacks from theoretical and practical viewpoints and argue...
Tipo: Text
Palavras-chave: Interpolation methods; Map; Quadratic entropy; Spatial statistics; Species diversity; Species richness; Beta-diversity.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00257/36819/37060.pdf

Suivi électronique de la mégafaune marine en Méditerranée nord-occidentale
Provedor de dados: 5
Autores: Bourjea, Jerome; Fromentin, Jean-marc.
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00487/59818/62961.pdf

Calanus and environment in the eastern North Atlantic. 1. Spatial and temporal patterns of C. finmarchicus and C. helgolandicus
Provedor de dados: 5
Autores: Planque, Benjamin; Fromentin, Jean-marc.
Spatial and temporal patterns of Calanusfinmarchicus and C. helgolandicus (Copepoda, Calanoida) were investigated in the northeast Atlantic and the North Sea from 1962 to 1992. The seasonal cycle of C.finmarchicus is characterised by a single peak of abundance in spring, whereas the seasonal cycle of C. helgolandicus shows 2 abundance maxima, one in spring and one in autumn. The former species mainly occurs in northern regions (limited by the 55*N parallel in the North Sea and by the 50*N parallel in the open ocean). The latter species shows 2 types of spatial patterns, occurring in the Celtic Sea during spring and in the Celtic Sea plus the North Sea in autumn. Differences in seasonal spatial patterns of Calanus species may result from different responses...
Tipo: Text
Ano: 1996
URL: http://archimer.ifremer.fr/doc/00033/14458/11760.pdf

A simulation framework to evaluate management strategies for Atlantic tunas: a preliminary example based on east Atlantic bluefin
Provedor de dados: 5
Autores: Kell, Laurence T; Fromentin, Jean-marc; Gauthiez, F; Restrepo, Victor.
The Ad Hoc Working Group on the Precautionary Approach (SCRS/99/11) recommended the development of a simulation modelling framework to investigate the performance of stock specific management strategies under a variety of realistic hypothesis about population and fishery dynamics. This paper describes a preliminary simulation model based on East Atlantic bluefin tuna developed using flexible software that allows the implications for management of a variety of plausible hypotheses about stock and fishery dynamics to be explored. The intention is to illustrate the ways in which such models can be used and the types of advice that they can provide
Tipo: Text
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00194/30566/28991.pdf

Descriptive analysis of the ICCAT bluefin tuna tagging database
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
The present paper proposes a simple descriptive analysis of the ICCAT bluefin tuna tagging database. Since 1954, about 91.2% of the tags were released in the West Atlantic and 8.8% in the East Atlantic. The great majority of tags was recaptured in their area of release, i.e., 95.7% and 97.25% for the East and the West Atlantic, respectively. The number of tags released in the West and recaptured in the East (102) was about 5 times higher than the reverse (19), but the percentage of transatlantic migrations from East-to-West (4.3%) was about 2 times higher than the one from West-to-East (2.25%). The percentage of transatlantic migrations varies over time, especially from West-to-East. It was much higher during the 90’s (7.6%) than in the three previous...
Tipo: Text
Palavras-chave: Conventional tag; Migration rates; Thunnus thynnus; East and West Atlantic stocks.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00194/30495/28904.pdf

Groupe de travail ICCAT d'évaluation de stock du thon rouge Atlantique. Madrid, 4-11 septembre 2012.
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain.
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00111/22267/19942.pdf

Preliminary results of aerial surveys of bluefin tuna in the western Mediterranean sea
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Farrugio, Henri; Deflorio, Michèle; De Metrio, Gregorio.
One of the aims of the EU project STROMBOLI (2000-2002) was to conduct an aerial survey for bluefin tuna in the western Mediterranean Sea to test the feasibility of computing an index of abundance from direct observation. This approach has at least two advantages: (i) to provide fishery-independent information and observation, and (ii) to compensate for the lack of Mediterranean purse seine CPUE indices. The first surveys were done in June-July 2000 over the Balearic and Sicilian areas, where and when adult bluefin tuna used to concentrate for spawning, but the results were disappointing (spawners can hardly be detected from a plane). In contrast, the results obtained from the surveys for juveniles of BFT in the Gulf of Lions and in the Ligurian and...
Tipo: Text
Palavras-chave: Atlantic bluefin tuna; Aerial survey; Index of abundance; Gulf of Lions; Ligurian and Tyrrhenian Sea.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00194/30531/28949.pdf

Results of the 2003 observer program on board the French purse seiner targeting Atlantic bluefin tuna in the Mediterranean sea
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Farrugio, Henri.
In 2003, IFREMER implemented an observer program on board of the French purse seiner targeting bluefin tuna (BFT) in the Mediterranean Sea to collect the size composition of catches. The protocol and the sampling design were established by IFREMER and the operations were carried out by two independent scientific observers (each one following a given boat over two distinguished fishing seasons). The 788 BFT measured by the two observers during the ~ 190 fishing days were mostly small/juveniles fish and solely represented 2.7% of the total catches. The sampling appears largely insufficient to be representative of this fleet and was furthermore strongly biased (big BFT being under-sampled). From our viewpoint, the implementation of a joint observer program on...
Tipo: Text
Palavras-chave: Atlantic bluefin tuna; Catch; Size composition; Observer; Purse seine; Mediterranean; By-catch.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00194/30502/28912.pdf

Time series analysis of tuna and swordfish catches and climate variability in the Indian Ocean (1968-2003)
Provedor de dados: 5
Autores: Corbineau, A; Rouyer, Tristan; Cazelles, B; Fromentin, Jean-marc; Fonteneau, A; Menard, Felix.
We analysed the patterns of variation that characterize 33 catch time series of large pelagic fishes exploited by the Japanese and Taiwanese longline fisheries in the Indian Ocean from 1968 to 2003. We selected four species, the yellowfin (Thunnus albacares), the bigeye (T. obesus), the albacore (T. alalunga), and the swordfish (Xiphias gladius) and aggregated data into five biogeographic provinces of Longhurst (2001). We carried out wavelet analyses, an efficient method to study non-stationary time series, in order to get the time-scale patterns of each signals. We then compared and grouped the different wavelet spectra using a multivariate analysis to identify the factors (species, province or fleet) that may influence their clustering. We also...
Tipo: Text
Palavras-chave: Indian Ocean; Dipole Mode Index; Longline fisheries; Wavelet analysis; Time series analysis; Pelagic fishes.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4714.pdf

Overfishing causes frequent fish population collapses but rare extinctions
Provedor de dados: 5
Autores: Le Pape, Olivier; Bonhommeau, Sylvain; Nieblas, Anne-elise; Fromentin, Jean-marc.
Tipo: Text
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00392/50387/51097.pdf

Spatio-Temporal Patterns of Key Exploited Marine Species in the Northwestern Mediterranean Sea
Provedor de dados: 5
Autores: Morfin, Marie; Fromentin, Jean-marc; Jadaud, Angelique; Bez, Nicolas.
This study analyzes the temporal variability/stability of the spatial distributions of key exploited species in the Gulf of Lions (Northwestern Mediterranean Sea). To do so, we analyzed data from the MEDITS bottom-trawl scientific surveys from 1994 to 2010 at 66 fixed stations and selected 12 key exploited species. We proposed a geostatistical approach to handle zero-inflated and non-stationary distributions and to test for the temporal stability of the spatial structures. Empirical Orthogonal Functions and other descriptors were then applied to investigate the temporal persistence and the characteristics of the spatial patterns. The spatial structure of the distribution (i.e. the pattern of spatial autocorrelation) of the 12 key species studied remained...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00087/19860/17507.pdf

Strategic research priorities to the Common fishery policy (CFP) with regard to global commitments (MSY, EAF, MFSD)
Provedor de dados: 5
Autores: Gros, Philippe; Biseau, Alain; Fromentin, Jean-marc; Thebaud, Olivier.
The report is focused on the research priorities pertaining to the implementation of the ‘maximum sustainable yield’ (MSY) and of the ‘ecosystem approach to fisheries’ (EAF). The MSY is first examined, taking account of its relevance as a management objective, of its link with maximum economic yield (MEY), and of its close relationship with ecosystem productivity and fishing capacity. Related research priorities are identified. In the second part, emphasis is put on EAF, a very challenge for fishery scientists. The extension of fisheries science towards an ecosystem dimension (including human activities) and the integration of uncertainty have opened up large fields of research. Priorities are presented by domain. Five principal areas of knowledge and...
Tipo: Text
Ano: 2008
URL: http://archimer.ifremer.fr/doc/00013/12408/9194.pdf

Rapid changes in growth, condition, size and age of small pelagic fish in the Mediterranean
Provedor de dados: 5
Autores: Van Beveren, Elisabeth; Bonhommeau, Sylvain; Fromentin, Jean-marc; Bigot, Jean-louis; Bourdeix, Jean-herve; Brosset, Pablo; Roos, David; Saraux, Claire.
Since 2007, the ecosystem of the Gulf of Lions has shifted to a different regime, characterised by a low anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) biomass and a remarkably high sprat (Sprattus sprattus) biomass. Surprisingly, the abundance and recruitment of anchovy and sardine remained high. To understand which processes (bottom-up or top-down control, etc.) could have caused this shift, we studied the changes in body condition, growth and size and age of anchovy, sardine and sprat over 1984–1985 and 1992–2012, using data from scientific surveys. The annual age structure of anchovy and sardine was estimated using Bayesian mixture models based on size frequency data with priors on the age–length relationship derived from independent...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00192/30335/29917.pdf

Measurement and analysis of small pelagic fish condition: A suitable method for rapid evaluation in the field
Provedor de dados: 5
Autores: Brosset, Pablo; Fromentin, Jean-marc; Menard, Frederic; Pernet, Fabrice; Bourdeix, Jean-herve; Bigot, Jean-louis; Van Beveren, Elisabeth; Perez Rodia, Maria A.; Choy, Sandrine; Saraux, Claire.
As condition is a key variable in population dynamics (especially for survival, growth and reproduction), the use of well-defined and accurate fish condition indices is capital. In particular, condition indices (morphometric, bioenergetic and biochemical) have never been compared and validated for the European anchovy Engraulis encrasicolus, the European pilchard Sardina pilchardus and the European sprat Sprattus sprattus. The accuracy of two indirect methods, the morphometric relative condition index Kn and the bioenergetics index determined with the Distell Fish Fatmeter was investigated by comparing with a direct measure of relative lipid content carried out with a thin layer chromatography-flame ionization detector. Estimations from the fatmeter...
Tipo: Text
Palavras-chave: Anchovy; Fatmeter; Lipids; Mediterranean Sea; Sardine; Sprat.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00226/33741/32304.pdf

Otolith shape variation provides a marker of stock origin for north Atlantic bluefin tuna (Thunnus thynnus)
Provedor de dados: 5
Autores: Brophy, Deirdre; Haynes, Paula; Arrizabalaga, Haritz; Fraile, Igaratza; Fromentin, Jean-marc; Garibaldi, Fulvio; Katavic, Ivan; Tinti, Fausto; Karakulak, F. Saadet; Macias, David; Busawon, Dheeraj; Hanke, Alex; Kimoto, Ai; Sakai, Osamu; Deguara, Simeon; Abid, Nouredinne; Santos, Miguel Neves.
Two stocks of bluefin tuna (Thunnus thynnus) inhabit the north Atlantic; the western and eastern stocks spawn in the Gulf of Mexico and the Mediterranean Sea respectively. Trans-Atlantic movements occur outside spawning time whereas natal homing maintains stock structure. Commercial fisheries may exploit a mixed assemblage of both stocks. The incorporation of mixing rates into stock assessment is precluded by uncertainties surrounding stock discrimination. Otolith shape descriptors were used to characterise western and eastern stocks of Atlantic bluefin tuna in the present study and to estimate stock composition in catches of unknown origin. Otolith shape varied with length and between locations and years. Within a restricted size range (200-297-cm fork...
Tipo: Text
Palavras-chave: Elliptical Fourier analysis; Population structure; Stock mixture analysis.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00346/45745/45381.pdf

Fluctuations of landings and environmental conditions in the north-western Mediterranean Sea
Provedor de dados: 5
Autores: Lloret, J; Lleonart, J; Sole, I; Fromentin, Jean-marc.
Most of the monthly catches and CPUE of 13 studied commercial species in the coastal waters of the north-western Mediterranean were significantly positively correlated with run-off of local rivers (Rhone and Muga) and the wind mixing index during the spawning season, with time lags of less than a year (transfer function analyses). Rhone and Ebre interannual fluctuations in run-off were synchronous and were related to the North Atlantic Oscillation (NAO), river run-offs being negatively correlated to high NAO episodes. The fluctuations of river discharges and the wind mixing index were cyclic but not related. The results showed that enhanced hydroclimatic conditions in the NW Mediterranean were favourable for the productivity of the fish and invertebrate...
Tipo: Text
Palavras-chave: Wind; Rhone River; NAO index; Muga River; Mediterranean fisheries; Gulf of Roses Cape Creus; Gulf of Lions; Ebre River; Box Jenkins models.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/2001/publication-672.pdf

Migration, residency, and homing of bluefin tuna in the western Mediterranean Sea
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Lopuszanski, Daniel.
This study presents the results of an electronic tagging programme on mature Atlantic bluefin tuna (ABFT) that has been conducted since 2007 offshore of the French Mediterranean Coast. The spatial distributions of ABFT showed little year-to-year variation and the fish concentrated in a small area of the central northwestern Mediterranean, where they may stay for several months. The individual tracks display sinuous trajectories in this area, indicating the possibility of feeding behaviour. No fish went out to the North Atlantic, but several fish displayed some migration to the southern western Mediterranean Sea during winter and the central Mediterranean during the spawning season. The homing behaviour of one fish after a full year as well as the back and...
Tipo: Text
Palavras-chave: Feeding area; Front; Marine protected area; Pop-up archival tag; Spatial distribution; Thunnus thynnus.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00165/27637/25835.pdf

Co-Occurrence and Habitat Use of Fin Whales, Striped Dolphins and Atlantic Bluefin Tuna in the Northwestern Mediterranean Sea
Provedor de dados: 5
Autores: Bauer, Robert; Fromentin, Jean-marc; Demarcq, Herve; Brisset, Blandine; Bonhommeau, Sylvain.
Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The...
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00284/39481/37969.pdf

Projections for east Atlantic and Mediterranean bluefin tuna
Provedor de dados: 5
Autores: Kell, Laurence T; Bonhommeau, Sylvain; Fromentin, Jean-marc; Ortiz, Mauricio; Walter, John.
The management plan for East Atlantic and Mediterranean bluefin tuna is based on the Kobe II strategy matrix (K2SM), which indicates the probability of SSB&gt;BMSY and F &lt;FMSY for different levels of catch projections. In this paper we document the projections for eastern Atlantic and Mediterranean bluefin tuna.
Tipo: Text
Palavras-chave: Stock assessment; Bluefin tuna.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00192/30276/28739.pdf

Combined effects of exploitation and temperature on fish stocks in the Northeast Atlantic
Provedor de dados: 5
Autores: Rouyer, Tristan; Fromentin, Jean-marc; Hidalgo, Manuel; Stenseth, Nils C.
Fish stock fluctuations are affected by two potentially confounding forces: the removal of individuals by fisheries and climatic variations affecting the productivity of fish populations. Disentangling the relative importance of these forces has thus been a question of primary importance for fisheries management and conservation. Through the analysis of long-term time-series for 27 fish stocks from the Northeast Atlantic, the present study shows that the sign and intensity of the effect of temperature on biomass are dependent on the geographical location: the stocks located at the southernmost and northernmost latitudes of our study displayed stronger associations with temperature than the stocks located in the middle range of latitudes. As a consequence,...
Tipo: Text
Palavras-chave: Combined climate/exploitation effect; Exploitation; Fish stocks; Northeast Atlantic; Response to climate; Time-series.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00230/34107/32821.pdf

Assessing causal links in fish stock–recruitment relationships
Provedor de dados: 5
Autores: Pierre, Maud; Rouyer, Tristan; Bonhommeau, Sylvain; Fromentin, Jean-marc.
Understanding whether recruitment fluctuations in fish stock arise from stochastic forcing (e.g. environmental variations) rather than deterministic forces (e.g. intrinsic dynamics) is a long standing question with important applied consequences for fisheries ecology. In particular, the relationship between recruitment, spawning stock biomass and environmental factors is still poorly understood, even though this aspect is crucial for fisheries management. Fisheries data are often short, but arise from complex dynamical systems with a high degree of stochastic forcing, which are difficult to capture through classic modelling approaches. In the present study, recent statistical approaches based on the approximation of the attractors of dynamical systems are...
Tipo: Text
Palavras-chave: Causality; Forecasting models; Marine.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00408/51930/52555.pdf

Size limits regulation for Tuna: should we also consider the protection of large fish?
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
A recent body of literature has demonstrated that older females produce larvae and offsprings that have much higher survival and growth than do younger adults and that they furthermore play a key role in the adaptability, persistence and productivity of the exploited fish populations. These findings, that have been shown for several pelagic, groundfish and rockfish species, are, thus, worth to consider for tuna and tuna-like species. The aim of this modest and brief paper is solely to draw the attention from the SCRS to this issue which may have considerable impacts on management regulations.
Tipo: Text
Palavras-chave: Age structure; Genetic diversity; Recruitment success; Sustainability; Management.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/00192/30333/28808.pdf

Long-term variations of four macrobenthic community structures
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Dauvin, Jean-claude; Ibanez, F; Dewarumez, Jean-marie; Elkaim, B.
This study examines whether meso-scale meteorological events, in particular the alternation of cold and mild periods, influenced the structure of four Abi cr alba communities, sampled from 1977 to 1992 on the northwest French coast. We propose a new numerical procedure to describe temporal variations in the structure of each assemblage, using some niche-oriented models recently developed by Tokeshi (1993). The description of the temporal changes in the structure of each community was summarized into a 2D-plot of an ordination, performed on observed and simulated patterns. Results showed that important changes occurred in these four assemblages, which were not directly related to the meso-scale climatic events, but mainly to the local environmental factors...
Tipo: Text
Palavras-chave: Macrobenthos community structure species abundance model long-term survey English Channel; North Sea.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00093/20407/18074.pdf

The True Challenge of Giant Marine Reserves
Provedor de dados: 5
Autores: Kaplan, David; Bach, Pascal; Bonhommeau, Sylvain; Chassot, Emmanuel; Chavance, Pierre; Dagorn, Laurent; Davies, Tim; Dueri, Sibylle; Fletcher, Rick; Fonteneau, Alain; Fromentin, Jean-marc; Gaertner, Daniel; Hampton, John; Hilborn, Ray; Hobday, Alistair; Kearney, Robert; Kleiber, Pierre; Lehodey, Patrick; Marsac, Francis; Maury, Olivier; Mees, Chris; Menard, Frederic; Pearce, John; Sibert, John.
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00139/25068/23186.pdf

Atlantic bluefin tuna: population dynamics, ecology, fisheries and management
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Powers, Joseph.
Both old and new information on the biology and ecology of Atlantic bluefin tuna have confronted scientists with research challenges: research needs to be connected to current stock-assessment and management issues. We review recent studies on habitat, migrations and population structure, stressing the importance of electronic tagging results in the modification of our perception of bluefin tuna population dynamics and behaviour. Additionally, we question, from both scientific and management perspectives, the usefulness of the classical stock concept and suggest other approaches, such as Clark's contingent and metapopulation theories. Current biological information confirms that a substantial amount of uncertainty still exists in the understanding of...
Tipo: Text
Palavras-chave: Tuna fisheries; Thunnus thynnus; Stock assessment and management; Population structure; Population dynamics; Atlantic bluefin tuna.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/publication-797.pdf

A phytosociological method for interpreting plankton data
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Ibanez, F.; Legendre, P.
Multivariate techniques allow data sets to be summarised, but are not deslgned to causally model ecological phenomena. The ambiguity of the interpretation results from the ambiguity of the scaling space. The phytosociological method proposed by Grandjouan (1982; These d'etat, Universite Louis Pasteur, Strasbourg) is a general interpretive framework allowing separate consideration of 3 distinct reference spaces. a geographical space to visualise the spatio-temporal distribution of the descriptors, an ecological space showing the effects of the environmental variables on the biological descriptors, and a bio-ethological space showing the statistically meaningful species cornmunities. It is thus possible to define the position of each biological category and...
Tipo: Text
Ano: 1993
URL: http://archimer.ifremer.fr/doc/00033/14454/11756.pdf

Potential feeding and spawning habitats of Atlantic bluefin tuna in the Mediterranean Sea
Provedor de dados: 5
Autores: Druon, Jean-noel; Fromentin, Jean-marc; Aulanier, Florian; Heikkonen, Jukka.
Atlantic bluefin tuna Thunnus thynnus (ABFT) is a fish of high market value which has recently become strongly overexploited, notably in the Mediterranean Sea. This area is an essential habitat for ABFT reproduction and growth. We present here an approach for deriving the daily mapping of potential ABFT feeding and spawning habitats based on satellite-derived sea surface temperature (SST) and chl a concentration. The feeding habitat was mainly derived from the simultaneous occurrence of oceanic fronts of temperature and chl a content while the spawning habitat was mostly inferred from the heating of surface waters. Generally, higher chl a contents were found to be preferred for the feeding habitat and a minimum SST value was found for the spawning habitat....
Tipo: Text
Palavras-chave: Habitat mapping; Bluefin tuna; Thunnus thynnus; Feeding; Spawning; Mediterranean Sea; Remote sensing; Satellite data.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00049/16053/13549.pdf

The key importance of the underlying stock-recruitment assumption when evaluating the potential of management regulations of Atlantic bluefin tuna
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
The aim of this study is to investigate the implications of different stock-recruitment assumptions when examining the potential of Dubrovnik’s bluefin tuna recovery plan. To do so, some Beverton and Holt relationships displaying contrasting steepness of 0.99, 0.90, 0.75 and 0.50 were applied within a simulation model. In addition to these four stock-recruitment scenarios, parental effects and stochastic variations were also considered. The main conclusion is that our ability to evaluate the consequences of the Dubrovnik agreement (as any set of management measures) relies on our capacity to predict future recruitment levels in an accurate way. Assuming a Beverton and Holt relationship with different steepness, with or without parental effects and with or...
Tipo: Text
Palavras-chave: Thunnus thynnus; Management regulations; Stock-recruitment; Parental effects; Stock rebuilding; Simulation model.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00192/30296/28784.pdf

Investigating the performances of a bayesian biomass dynamic model with informative priors on Atlantic bluefin tuna
Provedor de dados: 5
Autores: Simon, M; Fromentin, Jean-marc; Bonhommeau, Sylvain; Gaertner, Daniel; Etienne, Marie-pierre.
We examined the possibility of eliciting informative priors for the parameters of a biomass production model with emphasis on the intrinsic population growth rate of Atlantic bluefin tuna (Thunnus thynnus). We reviewed the literature to propose probability distribution functions for the vital rates and used a matrix population model structured by age (Leslie) to compute the population growth rate. A generalized biomass production model is applied on two CPUE and catch datasets (1976-1996 and 1976-2006) using informative priors. The population growth rate prior has a diffuse distribution and is very sensitive to young of the year mortality rate. Thus, we compared the performances of this prior with a commonly used prior for tunas population growth rate. We...
Tipo: Text
Palavras-chave: Bayesian model; Population growth rate; Uncertainties; Natural mortality; CPUE; Tuna fisheries; Thunnus thynnus.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00192/30281/28756.pdf

The fisheries history of small pelagics in the Northern Mediterranean
Provedor de dados: 5
Autores: Van Beveren, Elisabeth; Fromentin, Jean-marc; Rouyer, Tristan; Bonhommeau, Sylvain; Brosset, Pablo; Saraux, Claire.
Since 2007, the biomass of sardine and anchovy in the NW Mediterranean has remained persistently low, whereas the biomass of the commercially low-valued sprat has exploded. Also, simultaneous decreases in condition, size, and/or age of these populations were observed. Altogether, this resulted in a drop in landings of small pelagics. To understand the amplitude of these events and to provide a baseline scenario against which current changes can be compared, we compiled exceptionally long landing series (1865–2013) of sardine, anchovy, and mackerel for different subregions of the southern French coast. We characterized the fluctuations of these landings and compared these with environmental drivers (sea surface temperature, Rhône river discharge, North...
Tipo: Text
Palavras-chave: Anchovy; Fish landings; Gulf of Lions; Historical time series; Mackerel; Sardine.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00319/43001/42561.pdf

Update of the abundance index for juvenile fish derived from aerial surveys of bluefin tuna in the western Mediterranean Sea
Provedor de dados: 5
Autores: Rouyer, Tristan; Brisset, Blandine; Bonhommeau, Sylvain; Fromentin, Jean-marc.
Se describe un enfoque que hace posible ejecutar online el conjunto de códigos utilizados para la evaluación del stock de atún rojo del este (BFTE) de ICCAT. En 2014, el Grupo de especies de atún rojo de ICCAT ha podido ejecutar miles de ensayos de modelos utilizando la paralelización de códigos R y Fortran en un superordenador. Este nuevo enfoque tiene muchos beneficios científicos, pero muy pocos participantes podrían reproducirlo sin unas capacidades específicas. Desde noviembre de 2015, el H2020 BlueBridge project está financiando un ingeniero para crear un sitio web (o VRE de Entorno de investigación virtual) en el que los usuarios puedan parametrizar y ejecutar varios pasos del trabajo de la evaluación de atún rojo del este. Reempaquetando los...
Tipo: Text
Palavras-chave: Bluefin tuna; Scientific cloud; Stock assessment; Grid computing; Online processing.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00435/54638/56043.pdf

The Eastern Atlantic and Mediterranean bluefin tuna: an archetype of overfishing and rebuilding?
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Rouyer, Tristan.
The overexploitation of East Atlantic and Mediterranean bluefin tuna (ABFTE) stock has been considered as an archetype of overfishing and general mismanagement of national and international fisheries bodies. The crisis highlighted, among other things, the fact that uncertainties that are inherent to any scientific advice can be used in lobbying to attempt to discredit science-based management. It also showed how interactions between science and management can change through time according to public awareness and opinion. This long and highly publicized crisis finally came to an end, in 2009, when ICCAT, under the pressure of NGOs and public opinion, fully endorsed the scientific advice within a rebuilding plan. Nowadays, the ABFTE stock is recovering, even...
Tipo: Text
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00451/56277/57854.pdf

Back to the future: investigating historical data of bluefin tuna fisheries
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
The exploitation of Atlantic bluefin tuna in the Mediterranean Sea goes back to the first millennium before Christ and the Romans already took benefits of the bluefin tuna reproductive migration to catch them. Bluefin tuna catch did not remain stable along its millennium exploitation history but displayed conspicuous long-term fluctuations that could result from environmentally-driven changes in the bluefin tuna migration routes. The Nordic fisheries that took place in the Norwegian and North Sea in the early 1920s were the most spectacular example of Atlantic bluefin tuna fisheries collapse. During the 1950s, the Nordic fisheries were the most productive ones, catching up to 18,000 tons/year, but they suddenly crashed down without any warning in 1963....
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00193/30467/28872.pdf

Populations ichtyologiques de grands pélagiques. Sous-région marine Mers celtiques. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain.
Tipo: Text
Palavras-chave: Mers celtiques; Grands poissons pélagiques; Biocénose; Exploitation; Etat des stocks.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00328/43949/43522.pdf

Prey predator interactions in the face of management regulations: changes in Mediterranean small pelagics are not due to increased tuna predation
Provedor de dados: 5
Autores: Van Beveren, Elisabeth; Fromentin, Jean-marc; Bonhommeau, Sylvain; Nieblas, Anne-elise; Metral, Luisa; Brisset, Blandine; Jusup, Marko; Bauer, Robert Klaus; Brosset, Pablo; Saraux, Claire.
Thunnus thynnus Sardina pilchardus Engraulis encrasicolus
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00371/48215/50340.pdf

Habitats of ten demersal species in the Gulf of Lions and potential implications for spatial management
Provedor de dados: 5
Autores: Morfin, Marie; Bez, Nicolas; Fromentin, Jean-marc.
An improved knowledge of habitat utilization by demersal species is a pre-requisite for their spatial management. Based on scientific survey data collected over the period 1994-2010, the present study investigates relationships between 4 environmental factors and 10 demersal species in the Gulf of Lions (northwestern Mediterranean Sea). Generalized linear models provided statistically satisfying results in terms of both model explanatory and predictive powers. The 'biological zone' factors, based on the percentage of light penetration to the sea bottom and bottom temperature, were the most important factors, while sediments and benthic macrofauna were only significant for a few species. The type of associations varied among species, resulting in different...
Tipo: Text
Palavras-chave: Fish habitat; Marine living resources; Mediterranean; Generalized linear models; Model selection; Marine Protected Area; MARXAN.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00334/44502/45846.pdf

FLR: an open-source framework for the evaluation and development of management strategies
Provedor de dados: 5
Autores: Kell, Laurence T.; Mosqueira, I; Grosjean, P; Fromentin, Jean-marc; Garcia, D; Hillary, R; Jardim, E; Mardle, S; Pastoors, M.a; Poos, J.j.; Scott, F; Scott, R.
The FLR framework (Fisheries Library for R) is a development effort directed towards the evaluation of fisheries management strategies. The overall goal is to develop a common framework to facilitate collaboration within and across disciplines (e.g. biological, ecological, statistical, mathematical, economic, and social) and, in particular, to ensure that new modelling methods and software are more easily validated and evaluated, as well as becoming widely available once developed. Specifically, the framework details how to implement and link a variety of fishery, biological, and economic software packages so that alternative management strategies and procedures can be evaluated for their robustness to uncertainty before implementation. The design of the...
Tipo: Text
Palavras-chave: Uncertainty; Stock assessment; Software; Simulation framework; Precautionary approach; Open source; Management strategy evaluation; Bio economic modelling.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2732.pdf

The Status of Atlantic Bluefin Tuna Response
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00006/11698/8446.pdf

The Fate of Atlantic Bluefin Tuna
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00002/11303/7852.pdf

Complex interplays among population dynamics, environmental forcing, and exploitation in fisheries
Provedor de dados: 5
Autores: Rouyer, Tristan; Fromentin, Jean-marc; Menard, Felix; Calzelles, B; Briand, K; Pianet, R; Planque, Benjamin; Stenseth, N.
The patterns of variations in fisheries time series are known to result from a complex combination of species and fisheries dynamics all coupled with environmental forcing (including climate, trophic interactions, etc.). Disentangling the relative effects of these factors has been a major goal of fisheries science for both conceptual and management reasons. By examining the variability of 169 tuna and billfish time series of catch and catch per unit effort (CPUE) throughout the Atlantic as well as their linkage to the North Atlantic Oscillation (NAO), we find that the importance of these factors differed according to the spatial scale. At the scale of the entire Atlantic the patterns of variations are primarily spatially structured, whereas at a more...
Tipo: Text
Palavras-chave: Time series analysis; North Atlantic Oscillation; Atlantic tuna.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-3984.pdf

Long-term fluctuations in bluefin tuna trap catches: are they environmentally driven?
Provedor de dados: 5
Autores: Ravier-mailly, Christelle; Fromentin, Jean-marc.
We tested whether synchronous long-term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) trap catches, collected from the ancestral Mediterranean and Atlantic trap fishery, might be related to environmental changes in NAO and/or in temperature. Spectral analyses of trap catches and temperature displayed similar spectra with peak at low frequency whereas those of the NAO exhibited a broad band spectrum. Regression analyses and tests of correlation did not reveal any clear relationship between trap catches and NAO. In contrast, long-term fluctuations in trap catches appear to be negatively and significantly related to long-term trends in temperature. Underlying processes that could explain such a relationship are discussed, with special focus on...
Tipo: Text
Palavras-chave: Thunnus thynnus; NAO; Temperature; Trap fishery; Migration.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00194/30530/28940.pdf

Eastern Atlantic bluefin tuna: what we learn from historical time-series of trap catches
Provedor de dados: 5
Autores: Ravier, Christelle; Fromentin, Jean-marc.
More than one hundred long-term time-series of bluefin tuna catches from the ancestral Mediterranean and Atlantic trap fisheries are used to (1) estimate historical range of BFT yields in the Mediterranean and adjacent Atlantic and (2) investigate spatial and temporal patterns of fluctuations in trap catches. Mean historical catches were around 110 000 tunas/year (± 50 000), i.e. 15 000 tons/year (∈[7 000;25 000]). Fluctuations in trap catches are of large magnitude, periods of high abundance being up to seven times higher than those of low abundance. More interesting was the occurrence of 100-year-long periodic fluctuations as well as 20-year cycles. These medium- to long-term fluctuations, representing more than 50% of the total variability in the...
Tipo: Text
Palavras-chave: Thunnus thynnus; Time series analyses; Abundance; Population dynamics; Long-term changes; Trapfishing.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00194/30497/28906.pdf

An attempt to evaluate the recent management regulations of the east Atlantic and Mediterranean bluefin tuna stock through a simple simulation model
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
This manuscript proposes a simple simulation model to investigate the implications to the resources of the recent management regulations adopted for the East Atlantic and Mediterranean bluefin tuna stock. If perfectly implemented, the new regulations on minimum size and closed fishing areas mostly lead to a change in the selectivity pattern which moves towards older fish, so decreasing growth-overfishing. The potential sustainable yields therefore considerably increase (almost double in comparison to those that would be obtained without the new regulations) while the SSB can rapidly reach 20% of the virgin SSB. An error of 20% in the implementation of these new regulations affects their efficiencies and does not seem to allow the rebuilding of the SSB at a...
Tipo: Text
Palavras-chave: Bluefin tuna; Management regulations; Stock rebuilding; Simulation model.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/00192/30297/28787.pdf

The 2002 size composition of bluefin tuna catches of the French purse seine compared to those of the early 1990s and 2001
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
In 2002, about 40% of the yield of the French purse seine fleet targeting bluefin tuna came from the Gulf of Lions, 38% from the Balearic Islands and about 22% from the Malta-Lybia area (a new area for this fleet). The fleet caught, in the Gulf of Lions, mostly juvenile bluefin (mainly 2 and 3 years old), whereas both juveniles and adults were targeted and caught in the Balearic and Maltese areas. As in 2001, the 2002 size composition of bluefin catches have been estimated from the EU log-books and both years looked very similar. Calculating Kolmogorov-Smirnov two sample tests between the yearly size compositions of 1990-1995 and those of 2001 and 2002, indicated significant differences between these two pools of data. Finally, we confirm that if the...
Tipo: Text
Palavras-chave: Atlantic bluefin tuna; Catch statistics.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/00194/30482/28889.pdf

Resolving Hjort's Dilemma How Is Recruitment Related to Spawning Stock Biomass in Marins Fish?
Provedor de dados: 5
Autores: Cury, Philippe M.; Fromentin, Jean-marc; Figuet, Sarah; Bonhommeau, Sylvain.
The relationship between spawning fish abundance and the number of offspring, the so-called stock-recruitment relationship, is crucial for fisheries management and conservation measures. Using the most comprehensive data set ever assembled, we quantify this relationship for 211 fish stocks worldwide, revealing a global pattern with a pervasive asymptotic shape that shows increasing recruitment reaching an upper limit for values around half to two-thirds of parental biomass. This corroborates previous theoretical and modeling results. However, parental biomass is a predictor for only 5% to 15% of the variance in recruitment, demonstrating the weak predictive power of the stock-recruitment relationship in marine fish populations. Thus, there is a need to...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00253/36441/35000.pdf

The Atlantic Bluefin Tuna: A global perspective
Provedor de dados: 5
Autores: Fonteneau, Alain; Fromentin, Jean-marc.
This communication presents a global overview of Atlantic bluefin tuna biology, exploitation and management. The comparison between bluefin tuna and all other tuna species do show that this species is ranking number one among other tunas world wide in a wide range of its resources and fisheries characteristics. Bluefin tuna is for instance the gold winner in the category of fisheries (about 10,000 years of documented fisheries, the highest price in the market, the largest tuna taken), of its peculiar biology (large migration, homing, growth, etc.) and in the category of risks presently faced by the resource, because of its multiple scientific uncertainties still pending, its increasingly serious statistical problems and the heavy political context in the...
Tipo: Text
Palavras-chave: Pêche; Durabilité; Pêche abusive; Migration; Caractéristique du cycle vital; Fisheries; Sustainability; Overfishing; Migration; Life history trait.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00194/30568/28995.pdf

Analysing multiple time series and extending significance testing in wavelet analysis
Provedor de dados: 5
Autores: Rouyer, Tristan; Fromentin, Jean-marc; Stenseth, N; Cazelles, B.
In nature, non-stationarity is rather typical, but the number of statistical tools allowing for non-stationarity remains rather limited. Wavelet analysis is such a tool allowing for non-stationarity but the lack of an appropriate test for statistical inference as well as the difficulty to deal with multiple time series are 2 important shortcomings that limits its use in ecology. We present 2 approaches to deal with these shortcomings. First, we used 1/f beta models to test cycles in the wavelet spectrum against a null hypothesis that takes into account the highly autocorrelated nature of ecological time series. To illustrate the approach, we investigated the fluctuations in bluefin tuna trap catches with a set of different null models. The 1/f beta models...
Tipo: Text
Palavras-chave: Maximum covariance analysis; Surrogates; Wavelet significance testing; Wavelet clustering; Multivariate time series; Non stationarity.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4291.pdf

Update of the index of abundance of juvenile bluefin tuna in the western Mediterranean sea until 2011
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain; Brisset, Blandine.
Here we present an update of the aerial surveys that have been carried out by IFREMER in the western Mediterranean Sea since 2000. This collection of data enables the monitoring of the bluefin juvenile population since the Gulf of Lyon is considered as a nursery for young individuals. The detections of juvenile bluefin tuna are carried out along the same transects between 2000-2003 and then 2009-2011 and are used to calculate a fishery-independent index of bluefin tuna abundance. This index can therefore be included in the stock assessment procedure as an abundance index of juveniles.
Tipo: Text
Palavras-chave: Atlantic bluefin tuna; Thunnus thynnus; Aerial survey; Index of abundance; Gulf of Lyon; Strip transect.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00191/30275/28736.pdf

A catch curve analysis for east Atlantic and Mediterranean bluefin tuna
Provedor de dados: 5
Autores: Kell, Laurence; Bonhommeau, Sylvain; Fromentin, Jean-marc.
A catch-curve analysis using catch-at-age (CAA) data is performed to evaluate recent changes in selection pattern of the eastern Atlantic and Mediterranean bluefin tuna fishery. This was done in order to detect changes following the implementation of the Recovery Plan.
Tipo: Text
Palavras-chave: Bluefin tuna; Catch curves; Management; Selectivity; Stock assessment.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00191/30272/28732.pdf

Habitat suitability of the Atlantic bluefin tuna by size class: An ecological niche approach
Provedor de dados: 5
Autores: Druon, Jean-noel; Fromentin, Jean-marc; Hanke, Alex R.; Arrizabalaga, Haritz; Damalas, Dimitrios; Ticina, Vjekoslav; Quilez-badia, Gemma; Ramirez, Karina; Arregui, Igor; Tserpes, George; Reglero, Patricia; Deflorio, Michele; Oray, Isik; Karakulak, F. Saadet; Megalbfonou, Persefoni; Ceyhan, Tevfik; Grubisic, Leon; Mackenzie, Brian R.; Lamkin, John; Afonso, Pedro; Addis, Piero.
An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5-25kg, only feeding) and large (&gt; 25kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern –...
Tipo: Text
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00308/41953/41803.pdf

Recurrent and density-dependent patterns in long-term fluctuations of Atlantic bluefin tuna trap catches
Provedor de dados: 5
Autores: Royer, Francois; Fromentin, Jean-marc.
We present a methodology for the non-linear analysis of long-term ecological time series. Using a time-delay embedding procedure, we investigated the complexity of 1-dimensional signals and compared their structure to their stochastic counterparts. Recurrence-based statistics and surrogate testing were used for this purpose. The method was first tested on elementary models for illustrative purposes and its potentialities and limits reviewed. We then investigated the time structure of 6 Mediterranean bluefin tuna trap catches known to display long-term fluctuations. These time series showed significantly more determinism than linear stochastic processes, displaying more recurring patterns/states than stochastic surrogates. The short term structure of these...
Tipo: Text
Palavras-chave: Embedding; Surrogate testing; Density dependence; Recurrence; Thunnus thynnus.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1982.pdf

Aerial surveys of bluefin tuna in the Western Mediterranean sea: retrospective, prospective, perspective
Provedor de dados: 5
Autores: Bonhommeau, Sylvain; Farrugio, Henri; Poisson, Francois; Fromentin, Jean-marc.
While the current stock status of bluefin tuna (BFT) has been considered as declining, there remain considerable data limitations for its stock assessment in the Mediterranean Sea. The collection of fishery-independent data reveals to be crucial to compensate for the lack of Mediterranean purse seine CPUE indices as well as to overcome a potential halt in the bluefin tuna fishery that would impede the monitoring of the stock and the comparison to reference points. Here we present a retrospective of aerial surveys that have been carried out since 2000. It includes the protocol as well as a retrospective of temporal and spatial distribution of detected schools. We then propose several perspectives that could improve the data collection method itself and the...
Tipo: Text
Palavras-chave: Atlantic bluefin tuna; Aerial survey; Index of abundance; Gulf of Lions; Strip transect.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00192/30292/28775.pdf

An overview on the use of precautionary approach and tuna management
Provedor de dados: 5
Autores: Fonteneau, Alain; Fromentin, Jean-marc.
This paper develops a critical overview of the various problems and uncertainties faced in tuna stock assessment, management and conservation. This presentation is based on Atlantic tunas, but also on various tuna stocks worldwide. Tuna jisheries management is characterized by major uncertainties in the stock assessment; since these stock assessments are always done only on jishery data which are often biased. Fortunately most tuna stocks are showing a strong resistance to overfishing. These major characteristics of tuna stocks and jisheries, and the bias in the scientific analysis, are presented and discussed. As a result, many of the reference point recommended for the precautionary approach applied to jisheries are often quite inappropriate for tuna...
Tipo: Text
Palavras-chave: Tunas; Precautionay approach; Atlantic; Management; Assessment.
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00194/30564/28984.pdf

An evaluation of the implications of population structure on the current bluefin tuna advice framework
Provedor de dados: 5
Autores: Kell, Laurence T; Fromentin, Jean-marc; Bonhommeau, Sylvain.
The objectives of the comprehensive ICCAT Atlantic-Wide Research Programme on Bluefin Tuna (GBYP) are to improve data collection, knowledge of key biological and ecological processes, assessment models and management. An important element of which is to develop a robust advice framework consistent with the Precautionary Approach. The current advice framework, which is based upon Virtual Population Analysis, demonstrates how a Management Strategy Evaluation (MSE) framework can be used to evaluate the robustness of management advice to uncertainty about stock structure.
Tipo: Text
Palavras-chave: Bluefin; Management Strategy Evaluation; Robustness; Stock structure; VPA.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00192/30277/28740.pdf

Temporal fluctuations of doliolid abundance in the bay of Villefranche-sur-Mer (Northwestern Mediterranean Sea) from 1967 to 1990
Provedor de dados: 5
Autores: Menard, Frederic; Fromentin, Jean-marc; Goy, J; Dallot, S.
This study describes the temporal fluctuations of doliolid populations sampled in the Bay of Villefranche-sur-Mer (Northwestern Mediterranean Sea) from 1967 to 1990. The abundance level of doliolids (strongly dominated by Doliolum nationalis and Dolioletta gegenbauri phorozooids) was estimated weekly according to Frontier's (1969) ordinal scale. Population abundance shows important interannual variations. The series displays a clear upward trend from the late 1960s to the early 1980s; thereafter, the abundances remain at a high and steady level. Five annual patterns of abundance level changes are identified, using cluster analysis. The influence of hydrological and meteorological conditions on doliolid abundance is tested using a Markov regression model...
Tipo: Text
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00093/20431/18098.pdf

Open environmental databases for open-sea fisheries biologists
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Royer, Francois; Marsac, Francis.
The present working document aims to list the main environmental databases (including in-situ observations, remote-sensing data and ocean models outputs), that are currently available on the Net and of interest in open-sea fisheries biology and ecology.
Tipo: Text
Palavras-chave: In-situ observations; Remote sensing data collections; Ocean model outputs.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00194/30501/28911.pdf

Body reserves mediate trade-offs between life-history traits: new insights from small pelagic fish reproduction
Provedor de dados: 5
Autores: Brosset, Pablo; Lloret, Josep; Munoz, Marta; Fauvel, Christian; Van Beveren, Elisabeth; Marques, Virginie; Fromentin, Jean-marc; Menard, Frederic; Saraux, Claire.
Limited resources in the environment prevent individuals from simultaneously maximizing all life-history traits, resulting in trade-offs. In particular, the cost of reproduction is well known to negatively affect energy investment in growth and maintenance. Here, we investigated these trade-offs during contrasting periods of high versus low fish size and body condition (before/after 2008) in the Gulf of Lions. Female reproductive allocation and performance in anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) were examined based on morphometric historical data from the 1970s and from 2003 to 2015. Additionally, potential maternal effects on egg quantity and quality were examined in 2014/2015. After 2008, the gonadosomatic index increased for...
Tipo: Text
Palavras-chave: Maternal effect; Northwest Mediterranean; Anchovy; Sardine.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00353/46458/46233.pdf

Spatio-temporal patterns and environmental controls of small pelagic fish body condition from contrasted Mediterranean areas
Provedor de dados: 5
Autores: Brosset, Pablo; Fromentin, Jean-marc; Van Beveren, Elisabeth; Lloret, Josep; Marques, Virginie; Basilone, Gualtiero; Bonanno, Angelo; Carpi, Piera; Donato, Fortunata; Kec, Vanja Cikes; De Felice, Andrea; Ferreri, Rosalia; Gasparevic, Denis; Giraldez, Ana; Gucu, Ali; Iglesias, Magdalena; Leonori, Iole; Palomera, Isabel; Somarakis, Stylianos; Ticina, Vjekoslav; Torres, Pedro; Ventero, Ana; Zorica, Barbara; Menard, Frederic; Saraux, Claire.
Small pelagic fish are among the most ecologically and economically important marine fish species and are characterized by large fluctuations all over the world. In the Mediterranean Sea, low catches and biomass of anchovies and sardines have been described in some areas during the last decade, resulting in important fisheries crises. Therefore, we studied anchovy and sardine body condition variability, a key index of population health and its response to environmental and anthropogenic changes. Wide temporal and spatial patterns were investigated by analyzing separately data from scientific surveys and fisheries in eight Mediterranean areas between 1975 and 2015.  Results showed that anchovy and sardine body condition as well as maximum size in some areas...
Tipo: Text
Palavras-chave: Anchovy; Sardine; Fish health; Marine monitoring.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00363/47400/47936.pdf

Influence of environmental variability and age on the body condition of small pelagic fish in the Gulf of Lions
Provedor de dados: 5
Autores: Brosset, Pablo; Menard, Frederic; Fromentin, Jean-marc; Bonhommeau, Sylvain; Ulses, Caroline; Bourdeix, Jean-herve; Bigot, Jean-louis; Van Beveren, Elisabeth; Roos, David; Saraux, Claire.
Endogenous and environmental variables are fundamental in explaining variations in fish condition. Based on more than 20 yr of fish weight and length data, relative condition indices were computed for anchovy and sardine caught in the Gulf of Lions. Classification and regression trees (CART) were used to identify endogenous factors affecting fish condition, and to group years of similar condition. Both species showed a similar annual cycle with condition being minimal in February and maximal in July. CART identified 3 groups of years where the fish populations generally showed poor, average and good condition and within which condition differed between age classes but not according to sex. In particular, during the period of poor condition (mostly recent...
Tipo: Text
Palavras-chave: Anchovy; Sardine; Relative condition factor; NW Mediterranean Sea; Endogenous effect; Environmental effect.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00272/38334/36575.pdf

A management strategy evaluation framework for Mediterranean Atlantic bluefin tuna
Provedor de dados: 5
Autores: Kell, L. T.; Fromentin, Jean-marc.
This paper presents an example of Management Strategy Evaluation (MSE) for Mediterranean and East Atlantic bluefin tuna using the FLR open source framework. Scenarios corresponding to alternative plausible hypotheses about the stock dynamics were used to evaluate alternative management strategies and to test their robustness to implementation error e.g. catch mis-reporting. The strategies evaluated correspond to i) harvest control rule (HCR) based upon F0.1 (a proxy for FMSY ) with an objective of restoring the stock to a level that would “ permit the maximum sustainable catch” and ii) a reduction of fishing mortality on immature fish. The main conclusions were that the F0.1 HCR alone would not result in the recovery of the stock in the next 15 years and...
Tipo: Text
Palavras-chave: Thunnus thynnus; Management plans; Management strategy evaluation; Simulation model.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00194/30477/28884.pdf

Recruitment variability and environment: issues related to stock assessments of Atlantic tunas
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Restrepo, Victor.
Variations in recruitment and year-class strength of fish populations is a well known feature which can be related to three main factors: 1) human activity, mainly through overexploitation of the spawning stock, but also through pollution of the spawning and nursery areas; 2) biological processes, such as predation, cannibalism and competition and 3) environmental events. Life history traits of Atlantic tuna make the probability of a stable recruitment much higher for tropical tuna than temperate ones, but the latter are more adapted to the risks of recruitment failures than the former. As noise in the recruitment can lead to pseudo-cyclic variations in SSB and yields, trends in stock size and catches are also more likely in temperate Atlantic tuna. All...
Tipo: Text
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00194/30562/28983.pdf

Situation en 2011 des ressources exploitées par les flottilles françaises
Provedor de dados: 5
Autores: Biseau, Alain; Bellail, Robert; Bertignac, Michel; Biais, Gerard; Bigot, Jean-louis; Bouche, Ludovic; Bourjea, Jerome; Caro, Anthony; De Casamajor, Marie-noelle; Caill-milly, Nathalie; Drogou, Mickael; Duhamel, Erwan; Fifas, Spyros; Foucher, Eric; Fromentin, Jean-marc; Jadaud, Angelique; Lampert, Luis; Laurans, Martial; Lissardy, Muriel; Lorance, Pascal; Mahe, Jean-claude; Mahe, Kelig; Masse, Jacques; Morandeau, Gilles; Pawlowski, Lionel; Poisson, Francois; Reynal, Lionel; Roos, David; Verin, Yves; Vermard, Youen; Vigneau, Joel.
Ce document présente l'état des principaux stocks exploités par les flottes françaises en termes de mortalité par pêche et de biomasse de reproducteurs. La situation fin 2010 (début 2011) par rapport aux points de référence (de précaution et Fmsy) est indiqué lorsque les indicateurs sont estimés et que les références sont définies. Les grandes tendances en matière d'évolution des mortalités et biomasses sont également indiquées.
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00035/14656/11956.pdf

How does fishing alter marine populations and ecosystems sensitivity to climate?
Provedor de dados: 5
Autores: Planque, Benjamin; Fromentin, Jean-marc; Cury, Philippe; Drinkwater, Kenneth F.; Jennings, Simon; Perry, R. Ian; Kifani, Souad.
Evidence has accumulated that climate variability influences the state and functioning of marine ecosystems. At the same time increasing pressure from exploitation and other human activities has been shown to impact exploited and non-exploited species and potentially modify ecosystem structure. There has been a tendency among marine scientists to pose the question as a dichotomy, i.e., whether (1) "natural" climate variability or (2) fishery exploitation bears the primary responsibility for population declines in fish populations and the associated ecosystem changes. However, effects of both climate and exploitation are probably substantially involved in most cases. More importantly, climate and exploitation interact in their effects, such that climate may...
Tipo: Text
Palavras-chave: Resilience; Marine ecosystems; Demography; Climate fishing interactions.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/2010/publication-7384.pdf

Food in the Sea: Size Also Matters for Pelagic Fish
Provedor de dados: 5
Autores: Queiros, Quentin; Fromentin, Jean-marc; Gasset, Eric; Dutto, Gilbert; Huiban, Camille; Metral, Luisa; Leclerc, Lina; Schull, Quentin; Mckenzie, David; Saraux, Claire.
Small pelagic fish are key components of marine ecosystems and fisheries worldwide. Despite the absence of recruitment failure and overfishing, pelagic fisheries have been in crisis for a decade in the Western Mediterranean Sea because of a marked decline in sardine size and condition. This situation most probably results from bottom-up control and changes in the plankton community toward smaller plankton. To understand such an unusual phenomenon, we developed an original and innovative experimental approach investigating the mechanisms induced by a reduction in the quantity and size of sardine prey. While experimentations offer the unique opportunity to integrate behavior and ecophysiology in understanding key demographic processes, they remain rarely...
Tipo: Text
Palavras-chave: Experimentation; Small pelagics; Sardina pilchardus; Body condition; Bottom-up control.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00505/61669/65585.pdf

Can we detect the effects of environmental variations on fish populations through VPA outputs? the North Atlantic albacore case
Provedor de dados: 5
Autores: Kell, Laurence T; Fromentin, Jean-marc; Ortiz De Zarate, Victoria; Arrizabalaga, Haritz.
Past studies have indicated that numbers-at-age 1 of albacore may be correlated with the winter NAO index in the previous year. Two main hypotheses have been stressed to explain such observation, i.e. an impact of the NAO on the recruitment or on migration patterns and consequently in the availability and catchability of specific age classes to the surface fishery. The objective of the present paper is to test whether such processes can be distinguished using VPA outputs. We first computed simple cross-correlations between the NAO at various lags, catches-at-age, Numbers-atage and F-at-age estimated in the last assessment. Since results were inconclusive, simulations were undertaken. The results showed that the probability of detecting spurious...
Tipo: Text
Palavras-chave: Thunnus alalunga; North Atlantic Oscillation; Simulation model; Virtual population analysis; Correlation coefficient; NAO.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00194/30503/28913.pdf

A participatory scenario method to explore the future of marine social-ecological systems
Provedor de dados: 5
Autores: Planque, Benjamin; Mullon, Christian; Arneberg, Per; Eide, Arne; Fromentin, Jean-marc; Heymans, Johanna Jacomina; Hoel, Alf Håkon; Niiranen, Susa; Ottersen, Geir; Sandø, Anne Britt; Sommerkorn, Martin; Thébaud, Olivier; Thorvik, Thorbjørn.
Anticipating future changes in marine social‐ecological systems (MSES) several decades into the future is essential in the context of accelerating global change. This is challenging in situations where actors do not share common understandings, practices, or visions about the future. We introduce a dedicated scenario method for the development of MSES scenarios in a participatory context. The objective is to allow different actors to jointly develop scenarios which contain their multiple visions of the future. The method starts from four perspectives: “fisheries management,” “ecosystem,” “ocean climate,” and “global context and governance” for which current status and recent trends are summarized. Contrasted scenarios about possible futures are elaborated...
Tipo: Text
Palavras-chave: Barents Sea; Future studies; Multiple perspectives; Participatory fisheries management; Storylines; Uncertainty.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00485/59621/62647.pdf

Spatial Structure and Distribution of Small Pelagic Fish in the Northwestern Mediterranean Sea
Provedor de dados: 5
Autores: Saraux, Claire; Fromentin, Jean-marc; Bigot, Jean-louis; Bourdeix, Jean-herve; Morfin, Marie; Roos, David; Van Beveren, Elisabeth; Bez, Nicolas.
Understanding the ecological and anthropogenic drivers of population dynamics requires detailed studies on habitat selection and spatial distribution. Although small pelagic fish aggregate in large shoals and usually exhibit important spatial structure, their dynamics in time and space remain unpredictable and challenging. In the Gulf of Lions (north-western Mediterranean), sardine and anchovy biomasses have declined over the past 5 years causing an important fishery crisis while sprat abundance rose. Applying geostatistical tools on scientific acoustic surveys conducted in the Gulf of Lions, we investigated anchovy, sardine and sprat spatial distributions and structures over 10 years. Our results show that sardines and sprats were more coastal than...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00226/33739/32151.pdf

Cinétique de Abra alba (Mollusque bivalve) de 1977 à 1991 en Manche-Mer du Nord, relation avec les facteurs climatiques
Provedor de dados: 5
Autores: Dauvin, Jean-claude; Dewarumez, Jean-marie; Elkaim, B; Bernardo, D; Fromentin, Jean-marc; Ibanez, F.
Populations of Abra alba (Wood) (Mollusca : Bivalvia) were studied over a fifteen-years period at three sites: the southern part of the North Sea (Gravelines area), the Bay of Seine, and the Bay of Morlaix in the western English Channel. These surveys provide an example of long-term changes in a species considered as ''opportunistic'' and as a ''biological indicator'' of disturbance. A summed cumulated function was used to compare the changes of the Abra alba populations and of mean air temperature in each area. The graph of this function shows the timing and duration of changes. Four or five main periods were identified at each site, with a succession of periods of abundance, stability, and decrease. The abundance periods were separated by ten years in...
Tipo: Text
Palavras-chave: ABRA-ALBA; LONG-TERM CHANGES; CYCLES; CLIMATIC STRESS.
Ano: 1993
URL: http://archimer.ifremer.fr/doc/00099/21066/18692.pdf

Effect of minimum size regulations on east bluefin tuna (Thunnus thynnus L.) yield pe recruit
Provedor de dados: 5
Autores: Restrepo, Victor; Arrizabalaga, Haritz; Ortiz De Urbina, J M; Fromentin, Jean-marc.
A standard yield per recruit (YPR) analysis is used to analyse the effects of minimum size regulations on bluefin tuna from the Eastern stock (East Atlantic and Mediterranean). Analyses were based on a selectivity vector computed over the period 1990- 1994 for which data were more reliable and VPA (performed during the 2002 stock assessment) showed a relatively good convergence. This selectivity vector was modified according to different minimum size regulations and implementation error levels. It is concluded that: (i) perfect implementation of the size limit regulation adopted in 2004 would increase YPR by 4.3% relative to the size limit adopted in 2002, and by 8.8% relative to the pattern realized in the early 1990s; (ii) YPR is however expected to...
Tipo: Text
Palavras-chave: Yield/recruit; Yield predictions; Size limit regulations; Bluefin tuna.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/00194/30545/28964.pdf

Retrospective analysis of the bluefin tuna Nordic fisheries data
Provedor de dados: 5
Autores: Pusineri, Claire; Ravier, Christelle; Fromentin, Jean-marc.
A retrospective analysis (1951-1979) was carried out on the bluefin tuna Nordic fisheries (Norway and Germany) length and weight data distributions and compared to those of Barbate trap (Gibraltar strait, Spain) to test further Tiews’ hypothesis about the disappearance of bluefin tuna in northern seas. The cohorts were identified from weight/length distributions and compared using multivariate analyses. The results showed: (i) a synchronous ageing in the 4 fisheries, (ii) similar dominant cohorts between South Norway and Barbate in the one hand (cohorts born from 1948 to 1952) and North Norway and Germany on the other hand (cohort born in 1945), (iii) a synchronous drop (or collapse) in the catches that occurred in 1963and (iv) significant correlation...
Tipo: Text
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00194/30500/28910.pdf

Optimizing PAT data transmission: assessing the accuracy of temperature summary data to estimate environmental conditions
Provedor de dados: 5
Autores: Bauer, Robert; Forget, Fabien; Fromentin, Jean-marc.
Pop-up archival tags (PAT) provide summary and high-resolution time series data at predefined temporal intervals. The limited battery capabilities of PATs often restrict the transmission success and thus temporal coverage of both data products. While summary data are usually less affected by this problem, as a result of its lower size, it might be less informative. We here investigate the accuracy and feasibility of using temperature at depth summary data provided by PATs to describe encountered oceanographic conditions. Interpolated temperature at depth summary data was found to provide accurate estimates of three major thermal water column structure indicators: thermocline depth, stratification and ocean heat content. Such indicators are useful for the...
Tipo: Text
Palavras-chave: Mixed layer depth; Ocean heat content; Pop-up archival tags; PAT-style Depth-Temperature Profiles; Temperature at depth; Thermal stratification; Thermocline.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00287/39800/45102.pdf

Estimating the productivity of Atlantic bluefin tuna from validated scientific data
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain; Kell, Laurence; Restrepo, Victor.
Estimating the productivity of an exploited marine species is not an easy or a trivial task. In the case of Atlantic bluefin tuna, the productivity can hardly be estimated from the natural mortality rates or the stock recruitment relationships because the former have never been estimated for this species from scientific data, but only “guesstimated”, while the latter remain highly uncertain for both the eastern stock (BFTE) and the western stock (BFTW). To get a better idea of bluefin tuna productivity, we thus applied the approach by Jennings et al. (1998) who proposed a surrogate of r, r’, named the potential rate of population increase. We compared this parameter and age-at-maturity (and to some extent the individual growth curves) of 25 species...
Tipo: Text
Palavras-chave: Thunnus thynnus; Population growth rate; Fecundity; Maturity; CITES criteria.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00192/30293/28777.pdf

Importance and future of individual markers for the ecosystem approach to fisheries
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Ernande, Bruno; Fablet, Ronan; De Pontual, Helene.
The use of genetic, biochemical and electronic markers in population biology and ecology has been growing tremendously during the last two decades. The first part of this paper aims at reviewing the main principles and advances of these individual markers through a few key applications on exploited marine fish populations. The second part is more prospective and investigates some possibilities that could arise in the near future through: (i) the development of new markers, (ii) the combination of different markers and (iii) the combination of quantitative approaches-whether classical or new-with individual markers. It is finally stressed how crucial individual markers will be to unravel the biocomplexity of wild fish populations and the key role they...
Tipo: Text
Palavras-chave: Genetic marker; Biochemical marker; Electronic tag; Otolith; Isotope; Population structure; Statistical and mechanistic model; Fisheries.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00000/11163/7522.pdf

Update of the French aerial survey index of abundance for 2018
Provedor de dados: 5
Autores: Rouyer, Tristan; Brisset, B; Fromentin, Jean-marc.
The French aerial survey over the Gulf of Lions provide an important fisheries independent index for the stock assessment of eastern Atlantic bluefin tuna (EABFT, Thunnus thynnus). The present manuscript reminds the methodology employed for the survey and provides the update of the index for the year 2018, which displays a decrease compared to previous years. The year 2018 was characterized by relatively warm waters and a lack of strong northern wind events in the Gulf of Lions; the potential effect of the environmental conditions on the decrease observed is shortly discussed.
Tipo: Text
Palavras-chave: Juvenile Atlantic bluefin tuna; Northwest Mediterranean Fisheries independent abundance index; Aerial survey.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00615/72692/71696.pdf

Trends in the NE Atlantic and Mediterranean Bluefin Abundance
Provedor de dados: 5
Autores: Ravier, Christelle; Fromentin, Jean-marc.
Tipo: Text
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00194/30569/29005.pdf

Small pelagic fish dynamics: a review of mechanisms in the Gulf of Lions
Provedor de dados: 5
Autores: Saraux, Claire; Van Beveren, Elisabeth; Brosset, Pablo; Queiros, Quentin; Bourdeix, Jean-herve; Dutto, Gilbert; Gasset, Eric; Jac, Cyrielle; Bonhommeau, Sylvain; Fromentin, Jean-marc.
Around 2008, an ecosystem shift occurred in the Gulf of Lions, highlighted by considerable changes in biomass and fish mean weight of its two main small pelagic fish stocks (European anchovy, Engraulis encrasicolus; European sardine, Sardina pilchardus). Surprisingly these changes did not appear to be mediated by a decrease in fish recruitment rates (which remained high) or by a high fishing pressure (exploitation rates being extremely low). Here, we review the current knowledge on the population's dynamics and its potential causes. We used an integrative ecosystem approach exploring alternative hypotheses, ranging from bottom-up to top-down control, not forgetting epizootic diseases. First, the study of multiple population characteristics highlighted a...
Tipo: Text
Palavras-chave: Population dynamics; Top-down; Disease; Zooplankton; Exploited species; Bottom-up.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00427/53861/54903.pdf

Oceanographic changes and exploitation drive the spatio-temporal dynamics of Atlantic bluefin tuna (Thunnus thynnus)
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Reygondeau, Gabriel; Bonhommeau, Sylvain; Beaugrand, Gregory.
Atlantic bluefin tuna (ABFT) has always displayed spectacular changes in its spatial distribution, but the underlying mechanism of such variations still remains obscure. This study focuses on this challenging issue by scrutinizing the intriguing ‘Brazilian episode’ during which a large quantity of ABFT (a temperate species) was caught during the 1960s in the equatorial Atlantic. To investigate this event, we applied a niche model to an extensive data set of catch and environmental variables from 1960 to 2009. ABFT exhibited a remarkably large ecological niche, which matches well with our current knowledge of ABFT. Our results also depicted a high probability of ABFT occurrence in the South Atlantic and, more interestingly, favorable environmental...
Tipo: Text
Palavras-chave: Ecological niche model; Longline fisheries; Migration; Synergistic effects; Thunnus thynnus; Time series.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00164/27540/25819.pdf

Consequences of variations in carrying capacity or migration for the perception of Atlantic bluefin tuna (Thunnus thynnus) population dynamics
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Kell, L.
Spectacular long-term cycles (around 110 years), independent of human exploitation, have been seen in historical catches of Atlantic bluefin tuna (Thunnus thynnus). Previous studies indicated that such variations could have been generated by contrasting but equally plausible dynamic processes, i.e., changes in carrying capacity or migration. A simulation framework was therefore used to test whether the International Commission for the Conservation of Atlantic Tuna stock assessment model, i.e., a virtual population analysis (VPA), can capture such dynamics. The main outcome is that knowledge of the underlying process is crucial, because distinct hypotheses lead to different population dynamics and contrasting performances of the stock assessment model. The...
Tipo: Text
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3533.pdf

Fishing effects and life history traits: a case study comparing tropical versus temperate tunas
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Fonteneau, Alain.
This study aims to test whether exploitation affects tunas and tuna-like species displaying contrasting life history traits similarly. We first collected information on life history of 10 commercial Atlantic species and then compared this information using multivariate analysis. On one hand, tropical tunas are characterised by small to medium size, rapid growth, early age-at-maturity, long spawning duration and short life span. These species, therefore, display a rapid turnover, characteristic of r-selected species. On the other hand, temperate tunas display differing life history traits, i.e., large size, slow growth, late age-at-maturity, short spawning duration and long life span. The turnover of these species is slow and present characteristics similar...
Tipo: Text
Palavras-chave: Management measures; Sustainability; Fishing; Long term fluctuations; Simulation modelling; Skipjack; Bluefin tuna.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/2001/publication-434.pdf

Effects of Stochasticity in Early Life History on Steepness and Population Growth Rate Estimates: An Illustration on Atlantic Bluefin Tuna
Provedor de dados: 5
Autores: Simon, Maximilien; Fromentin, Jean-marc; Bonhommeau, Sylvain; Gaertner, Daniel; Brodziak, Jon; Etienne, Marie-pierre.
The intrinsic population growth rate (r) of the surplus production function used in the biomass dynamic model and the steepness (h) of the stock-recruitment relationship used in age-structured population dynamics models are two key parameters in fish stock assessment. There is generally insufficient information in the data to estimate these parameters that thus have to be constrained. We developed methods to directly estimate the probability distributions of r and h for the Atlantic bluefin tuna (Thunnus thynnus, Scombridae), using all available biological and ecological information. We examined the existing literature to define appropriate probability distributions of key life history parameters associated with intrinsic growth rate and steepness, paying...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00115/22640/20362.pdf

Potential impacts of TAC implementation on the perception of the east Atlantic and Mediterranean bluefin tuna stock status
Provedor de dados: 5
Autores: Bonhommeau, Sylvain; Fromentin, Jean-marc.
This study aims at examining the potential bias in the VPA estimates by simulating a population, catch and CPUEs over 39 years from 1970 to 2008. In the operational model, two levels of noise were added to catch and CPUEs (50 and 100%), three fishing patterns were explored (F=FMSY, F increases linearly from 0.5 FMSY to 2.5 FMSY, F increases linearly from 0.5 FMSY to 2.5 FMSY over the first 34 years and decreases down to FMSY over the last 5 years). We also tested different hypothesis about the impact of the terminal F-ratios, and the natural mortality used in the current VPA as well as the impact of randomly generated CPUE for long-line and trap CPUE. Results show that the VPA is robust to estimate the SSB whatever the noise level in the catch and the...
Tipo: Text
Palavras-chave: Bluefin tuna; Stock assessment; VPA; Management regulations; TAC.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00192/30280/28755.pdf

Estimates of selectivity for the east Atlantic and Mediterranean bluefin tuna from 1970 to 2009
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain.
This study aims at examining the selectivity patterns among gears and years of the fleets targeting bluefin tuna in the Northeast Atlantic and Mediterranean Sea between 1970 and 2009, using catch curve analyses. The main outputs may be summarized as follow: (i) the general pattern of selectivity has highly varied through time, moving from ages 1-3 to ages 10+ from the 1970s to the 2000s; (ii) this important temporal drift primarily resulted from changes in PS selectivity patterns; (iii) these drastic variations in selectivity among gears and years can affect simple indicators which do not incorporate such information; (iv) the catch-at-age (CAA) matrix seems to be impaired by several inconsistencies that affect primarily the partial CAA of the purse...
Tipo: Text
Palavras-chave: Gear selectivity; Stock assessment; Bluefin tuna.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00192/30279/28747.pdf

Populations ichtyologiques de grands pélagiques. Sous-région marine Golfe de Gascogne. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Bonhommeau, Sylvain.
Tipo: Text
Palavras-chave: Golfe de Gascogne; Grands poissons pélagiques; Biocénose; Exploitation; Etat des stocks.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00329/44029/43601.pdf

Environmental noise affects the fluctuations of Atlantic large pelagics
Provedor de dados: 5
Autores: Rouyer, Tristan; Fromentin, Jean-marc; Stenseth, Nils Chr.
Environmental variables affect many processes of fish biology and their fluctuations are thought to be one of the main factors in variability of fish stocks. Recent work has shown that the variability of the environment in the frequency domain (i.e., the environmental noise) can interact with endogenous processes (e.g., density dependence) and affect fluctuations of animal populations. In this study, we investigate whether fluctuations of large pelagics' time series are affected by environmental noise and whether life-history traits of species modulate this response. By analysing several environmental variables and a large dataset of tuna and billfish catch per unit effort (CPUE) time series from the Atlantic, we show that in environments dominated by...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00011/12230/9083.pdf

Biodiversité et dynamique des communautés biologiques en milieu marin
Provedor de dados: 5
Autores: Fromentin, Jean-marc; Aliaume, Catherine; Lebaron, Philippe.
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00486/59816/62959.pdf

Are EU log-books suitable to compute size frequencies of bluefin tuna catches of the French purse seiners?
Provedor de dados: 5
Autores: Fromentin, Jean-marc.
The 2001 size composition of Atlantic bluefin tuna catches of the French purse seiners has been estimated from the EU log-books and appears roughly in agreement with those estimated from the local seafood traders between 1982 and 1998. However, the accuracy of the 2001 size composition remains uncertain because of a lack of a standard protocol and of sampling on catch coming from heterogeneous and/or multiple shoals. Regarding the spatial and temporal dynamic of the French fishery, an observer program should be implemented to correct and validate the size frequencies of these catches.
Tipo: Text
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00194/30526/28938.pdf