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Registros recuperados: 19
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A catch curve analysis for east Atlantic and Mediterranean bluefin tuna ArchiMer
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
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A state-space model to derive bluefin tuna movement and habitat from archival tags ArchiMer
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
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An attempt to evaluate the recent management regulations of the east Atlantic and Mediterranean bluefin tuna stock through a simple simulation model ArchiMer
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
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Analysis of the potential impact of several management measures for eastern Atlantic bluefin tuna on the basis of yield per recruit ArchiMer
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
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Disponibilité à des fins d'aquaculture des différents âges de thon rouge en atlantique est ArchiMer
Bard, François-xavier.
In order to clear up possibilities to get bluefin tuna of various age in Eastern Atlantic, main conclusions on availability of bluefin in Eastern Atalntic are given, using results of International Commission for Conservation of Atlantic Tuna.
Tipo: Text Palavras-chave: Thons rouges; Méditerranée; Atlantique Est; Pêcheries; Disponibilité; Bluefin tuna; Mediterranea; East Atlantic; Fisheries; Availability..
Ano: 1978 URL: http://archimer.ifremer.fr/doc/1978/publication-6027.pdf
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Estimates of selectivity for eastern Atlantic bluefin tuna from catch curves ArchiMer
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
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Estimates of selectivity for the east Atlantic and Mediterranean bluefin tuna from 1970 to 2009 ArchiMer
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
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Fishing effects and life history traits: a case study comparing tropical versus temperate tunas ArchiMer
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
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Indices of bluefin tuna (Thunnus thynnus thynnus) abundance derived from sale records of French purse seine catches in the Mediterranean sea ArchiMer
Labelle, Marc; Hoch, Thierry; Liorzou, Bernard; Bigot, Jean-louis.
Sampling operations are not routinely conducted in France to monitor the landings of bluefin tuna caught by purse seiners in the Mediterranean. The length, weight and age frequencies of bluefin caught by this fleet are predicted based on sale records, length-at-age and weight-length relations, trends in fishing and natural mortality rates, and other ancillary data. The resulting length frequencies are more accurate than those predicted by Liorzou and Bigot (1992) using a simpler algorithm, and are spread more evenly across adjacent size classes. Catch-per-unil-effort (CPUE) was expressed as the numbers of age 2 bluefin caught per successful seine fishing trip in the Gulf of Lions fall fishery. CPUE indices were computed by several methods, and compared to...
Tipo: Text Palavras-chave: Thon rouge; Senne tournante; Prises-par-unité-d'effort; Indices d'abondance; Taux de croissance; Évaluation des stocks; Mer Méditerranée; Bluefin tuna; Purse seine; Catch-per-unit-effort; Abundance indices; Growth rates; Stock-assessment; Mediterranean sea.
Ano: 1997 URL: http://archimer.ifremer.fr/doc/00188/29880/28357.pdf
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Mitochondrial Genetic Characterization Of Bluefin Tuna (Thunnus Thynnus) From Three Mediterranean (Libya, Malta, Tunisia); And One Atlantic Locations (Gulf Of Cadiz). OceanDocs
Farrugia, A.F.; Pla, C.; Viñas, J.; Tawil, M.Y.; Hattour, A.; de la Serna, J.M..
None of the previous genetic analysis found significant differences within the Mediterranean. However, a more exhaustive analysis is needed inside this sea. In this sense, we have analyzed the mitochondrial control region sequence variability of three Mediterranean locations: Libya (n = 22), Tunisia (n = 23) and Malta (n = 12). Additionally a sample from the Gulf of Cadiz (n = 24) in the East Atlantic Ocean was also included in the study. The AMOVA analysis revealed slightly (Fst = 0.013) but significative genetic differences (P < 0.000) for the Malta location, probably due to its small sample size (n = 12). In the other hand, when this location is removed from the analysis, no differences where found among the three remaining location (Fst = 0,005; P =...
Tipo: Journal Contribution Palavras-chave: Atlantic ocean; Mitochondrial DNA; Bluefin tuna; Sequencing; Genetic characterization; Mediterranean sea; Tuna fisheries.
Ano: 2003 URL: http://hdl.handle.net/1834/792
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Nouvelles donnees sur la reproduction du thon rouge (Thunnus thynnus L.) et d'autres especes de thonides en Mediterranee ArchiMer
Duclerc, J; Sacchi, J; Piccinetti, C; Piccinetti-manfrin, G; Dicenta, A; Barrois, J-m.
Two international research cruises on board of the research vessel 'Ichthys' the first one in Aug-Sept 1971, and the second other in June-July 1972, have shown the reproduction of Thunnus thynnus, T.alalunga, Auxis thazard and Sarda in the surroundings of the Balearic Islands. The observations were made on the planctonic stages of these spp and on the physico-chemical and biological conditions of the environment. Some data were also collected on the presence of juvenile or mature stages of these fishes and on their fishery.
Tipo: Text Palavras-chave: Plankton; Eggs; Larvae; Physico chemical conditions; Mediterranean sea; Reproduction; Thunnidae; Bluefin tuna.
Ano: 1973 URL: http://archimer.ifremer.fr/doc/1973/publication-2159.pdf
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Online collaborative environment to run the eastern bluefin tuna stock assessment workflow ArchiMer
Imzilen, Taha; Bonhommeau, Sylvain; Rouyer, Tristan; Kell, Laurence T; Barde, Julien.
In this note, we describe an approach which makes possible to execute online the set of codes used for eastern bluefin tuna (BFT-E) stock assess-ment at ICCAT. In 2014, ICCAT BFT-E working group has been able to execute thousands of model runs by using parallelization of R and Fortran codes on a supercomputer. This new approach has a lot of scientific benefits, but very few participants would be able to reproduce it without specific skills. Since november 2015, the H2020 BlueBridge project is funding an engineer to set up a WebSite (or VRE for Virtual Research Environment) where users will be able to parametrize and execute various steps of the BFT-E stock assessment workflow. By repackaging codes provided by ICCAT BFT-E working group the same codes are...
Tipo: Text Palavras-chave: Bluefin tuna; Scientific cloud; Stock assessment; Grid computing; Online processing.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00403/51471/52042.pdf
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Potential feeding and spawning habitats of Atlantic bluefin tuna in the Mediterranean Sea ArchiMer
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
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Potential further considerations on the conditioning of operating models of Atlantic Bluefin Tuna ArchiMer
Kimoto, A; Walter, Jf; Sharma, R; Rouyer, Tristan.
ICCAT BFTWG completed the stock assessment using multiple stock assessment methods in 2017, and they are going to proceed with the MSE process: development of MP in 2018. It is well recognized that the performance results of MPs often depend on the design of the OM and its conditioning that capture the range of potential population dynamics. It is therefore critical to consider them carefully before moving to the development of MP, but this has been a monumental task given the complexity of ABFT. The ICCAT GBYP Core modelling group has developed the OM by incorporating the mixing between two stocks, and the trial specifications. However, the 2017 stock assessment raised a number of issues that may require further consideration for the OMs, particularly...
Tipo: Text Palavras-chave: Bluefin tuna; Conditioning; Operating model; Uncertainty; Management procedure; MSE.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00484/59607/62624.pdf
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Potential impacts of TAC implementation on the perception of the east Atlantic and Mediterranean bluefin tuna stock status ArchiMer
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
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Projections for east Atlantic and Mediterranean bluefin tuna ArchiMer
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>BMSY and F <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
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Review and update of the French and Spanish purse seine size at catch for the Mediterranean bluefin tuna fisheries 1970-2010 ArchiMer
Gordoa, A; Rouyer, Tristan; Ortiz, M.
Tipo: Text Palavras-chave: Bluefin tuna; Purse seine; Mediterranean sea; Size structure.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00490/60191/63534.pdf
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The efficiency of using remote sensing for fisheries enforcement:Application to the Mediterranean bluefin tuna fishery ArchiMer
Cicuendez Perez, Juan; Alvarez, Marlene Alvarez; Heikkonen, Jukka; Guillen Garcia, Jordi; Barbas, Thomas.
This paper analyzes the impact of applying vessel detection technology using satellite images (vessel detection system, VDS) to complement air patrols for fisheries enforcement and control. Due to limited fisheries enforcement budgets there is the need to allocate costs efficiently among competing control tools. This paper focuses on assessing the benefits of using VDS jointly with VMS (vessel monitoring system) and air patrol surveillance to improve effectiveness of controls. A statistical model to estimate the number of inspections was developed and was used with enforcement costs data as reported by a number of EU countries. The result of applying VDS in fisheries enforcement is presented in one of the most demanding fisheries enforcement contexts: the...
Tipo: Text Palavras-chave: Vessel detection system; Synthetic Aperture Radar; Illegal fishing; Cost-benefit analysis; Bluefin tuna.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00141/25205/23389.pdf
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Update of the abundance index for juvenile fish derived from aerial surveys of bluefin tuna in the western Mediterranean Sea ArchiMer
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
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