|
|
|
| Registros recuperados: 173 | |
|
|
| Read, Andrew J; Duke University; aread@duke.edu; Brownstein, Carrie R; Duke University; cbrownstein@audubon.org. |
| After decades of overexploitation and severe depletion, Atlantic herring stocks in waters of the northeastern United States have recovered. Fishery managers now consider the herring resource to be underexploited. Nevertheless, some fishery managers and sustainable fishery advocates in New England have expressed concern that the fishery management plan may not adequately consider the importance of herring as prey for marine mammals, seabirds, and piscivorous fish. Several studies suggest that consumption by these predators is significant, yet trophic interactions are not explicitly considered in stock assessment models. Instead, as in most fisheries stock assessments, predation is subsumed within the natural mortality rate, and no empirical estimates of... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Atlantic herring; Ecosystem management; Fisheries management; Gulf of Maine; Marine mammals; Piscivores; Protected species; Single-species approach; Stock assessment; Trophic interactions. |
| Ano: 2003 |
|
| |
|
|
| Mesnil, Benoit. |
| The Catch-Survey Analysis (CSA) method of assessment aims at estimating stock abundance from relative indices by filtering measurement error in the latter through a simple two-stage population dynamics model. The method is not widely used and the associated literature is still limited. The objective of this work is to improve current understanding of the properties of the method, using data generated from a known fully age-structured population. A sensitivity analysis confirms that CSA is capable of providing reliable information about general stock trends. However, absolute estimates are sensitive to the parameter relating survey catchabilities of the two stages, which needs to be estimated externally with methods that warrant further validation. Biased... |
| Tipo: Text |
Palavras-chave: Data limited environments; Collie Sissenwine model; Catch Survey Analysis; Stock assessment. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-439.pdf |
| |
|
|
| 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 |
| |
|
|
| Lazard, Coline; Verin, Yves; Auber, Arnaud. |
| IBTS surveys (International Bottom Trawl Survey) are carried out within an international framework. Main countries bordering the North Sea participate to it according to the European Community regulations (EC N°1543/2000 and N° 1639/2001) which specify that countries from E.U. have to carry out surveys at sea in order to evaluate abundance and stocks distribution, independently of commercial fisheries data. The first target of the IBTS survey is to have a diagnosis on the main commercial fish stock and to calculate abundances index by age for these species. This survey started in the years 70’s and gradually standardised. Since the years 80’s, a common protocol is implemented and used by all participants. The same fishing gear and the same working methods... |
| Tipo: Text |
Palavras-chave: North sea; GOV; Beam trawl; MIK; Abundance; Stock assessment. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00507/61899/65990.pdf |
| |
|
|
| 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 |
| |
|
|
| Rey-valette, H; Martins, P. |
| A new programme concerning the experimentation of about thirty Fish Aggregating Devices (FADs) is to start in the Cape Verde Islands at the end of 1999. In this context, this communication is intended: - to evaluate the halieutic, economic and social conditions of the artisanal fishery in this archipelago, notably in terms of assets and constraints. Although these conditions are very heterogeneous depending on islands, the fads seem to be able to help the stabilization and the development of the fishing activities, disadvantaged by a low productivity, limited operating ranges of boats, and very irregular outings at sea. But the narrowness of the domestic market is likely to cause drops in the fish prices if the production increases, while the absence of... |
| Tipo: Text |
Palavras-chave: Attracting techniques; Capture fishery economics; Fishery management; Operational costs; Stock assessment; Tuna fisheries; Article Geographic Terms: Cape Verde Is.. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00042/15317/12644.pdf |
| |
|
| |
|
| |
|
|
| Pitel, Mathilde; Fifas, Spyros; Huet, Jerome; Berthou, Patrick. |
| During the 1950s, the clam played only a bit part in the local maritime context. It was the focus of a different fleet than the king scallop fleet, with a lesser fishing capacity (fleet from the Relecq Kerhuon) and an average annual catch of around 150 tonnes. In the 1960s, with a drop in the king scallop stock, the clam became a substitution resource with productions of over 400 tonnes. The first stages of this evolution are detailed by Le Gall (1969) and Piboubès (1973). Slowly, the fleet developed (from the 70s on, with the progressive arrival of seaweed boats in the fishery) The drop of the production until the disruption of the fishery in the 1980s is the combined consequence of the increase of the fishing capacities with an unfavourable populating... |
| Tipo: Text |
Palavras-chave: Venus verrucosa; Stock assessment; Clams; Bay of Brest; Brittany; Venus verrucosa; Évaluation de stock; Praires; Rade de Brest; Bretagne. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/rapport-4607.pdf |
| |
|
|
| 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 |
| |
|
|
| Trenkel, Verena. |
| In my work, which is summarised in this paper for obtaining accreditation to supervise research (the HDR), I addressed three areas: i) statistical methods of estimating the density of living resources, ii) mathematical models of population dynamics for estimating the abundance of marine populations and iii) methods for detecting temporal changes in the status of exploited populations. My work has focused on: i) Many studies of the observability of fish by trawling and by video and the development of stochastic models to better assess local fish densities. ii) Development of models without commercial catches, using Bayesian and frequentist approaches; the study of multi-specific relationships and the proposal for a threshold predator-prey model. iii)... |
| Tipo: Text |
Palavras-chave: Statistics; Abundance estimation; Stock assessment; Statistiques; Estimation d'abondance; Evaluation des stocks. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/rapport-1545.pdf |
| |
|
| |
|
|
| Bacher, Cedric; Chai, Ai-ling; Goulletquer, Philippe. |
| The krlging technique Is now employed ln more and more fields: mlnlng (Journel. 1977), hydrology (Delhomme, 197B; Shamsi et al" 1988; Dingman et al" 1988), fishery (Conan, 1989) and ecology (Robertson, 1987; Schotzko and O'Keeffe, 1989, 1990). Recent developments of the mathematlcal theory tend to extend the number of applications where Il may be used. Baslcally defined for the case of a statlonary spatial process, It now encompasses more general processes assuming less and less strong hypotheses (Intrinsic hypothesls, Intrlnsic generalised hypothesis, disjunctive krlglng). In its most general formulation, it allows to study the spatial structure of a process including large scale or local trends. The basic idea remains to take Into account the spatial... |
| Tipo: Text |
Palavras-chave: Kringing technique; Stock assessment; Oysters; Crassostrea virginica; Chesapeake Bay. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00200/31110/29518.pdf |
| |
|
|
| Marandel, Florianne; Lorance, Pascal; Trenkel, Verena M.. |
| The thornback ray (Raja clavata) in the Bay of Biscay is presumed to have declined during the 20th Century. To evaluate this decline and estimate biomass trajectories, a hypothetical catch time series was created for the period 1903-2013. A Bayesian state-space biomass production model with a Schaefer production function was fitted to the hypothetical catch time series and to a shorter research vessel Catch Per Unit Eeffort (CPUE) time series (1973-2013, with missing years). A censored likelihood made it possible to obtain biomass estimates without a CPUE time series or only with an estimate of biomass depletion. A simulation-estimation approach showed a high sensitivity of results to the prior for the intrinsic growth rate. The model provided biomass... |
| Tipo: Text |
Palavras-chave: Population dynamics; Stock assessment; Data poor; Censored data; Bayes; Thornback ray; State-space model. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00359/47032/46947.pdf |
| |
|
|
| 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 |
| |
|
|
| Charuau, Anatole; Chesnier, Véronique; Conan, Gérard; Derennes, Marc; Destanque, Catherine; Guenole, Annie; Isifou, Amadou; Jezequel, Michèle; Miossec, Gilbert; Missaoui, Ichmi; Morizur, Yvon; Rivoalen, Jean-jacques. |
| Introduction : Since 1978, new measures to better manage lobster fisheries were implemented in the Celtic Sea within the context of Community regulations. Meshing, in particular, was set at 60mm, but many owners, in order to maintain sufficient leeway vis-à-vis the regulations and to avoid administrative hassles adopted at the outset fish meshing at 70mm, even 80mm. Certain habits aiming to compensate for the losses due to these increases were established: Adoption of better-performing trawls, increase in the secondary catch and enlargement of the fisheries. At the same time, especially because of strong demand from international bodies, OEM and especially EEC, knowledge about the lobster spread and more reliable assessments were achieved, the main problem... |
| Tipo: Text |
Palavras-chave: Stock assessment; Norway lobster; Celtic sea; Nephrops Norvegicus; Crustacea; Lobster fishery; Mer Celtique; Nephrops Norvegicus; Crustacea; Effort Peche; Sex Ratio; Capture; Relation Taille Poids; Maillage; Chalut; Gestion stock; Peche. |
| Ano: 1982 |
URL: http://archimer.ifremer.fr/doc/1982/rapport-2337.pdf |
| |
|
| |
|
|
| Lazard, Coline; Verin, Yves; Auber, Arnaud. |
| In 2021, the French NS-IBTS Q1 survey was conducted as part of the International Bottom Trawl Survey program carried out by main countries bordering the North Sea in order to assess abundance and stocks distribution, independently of commercial fisheries data. The first target of the NS-IBTS Q1 survey is to provide a diagnosis on the main commercial fish species by estimating their abundance per age. A standardized protocol is rigorously applied by all participants. The R/V Thalassa sampled the eastern part of the Channel and southern North Sea (until 56° N) from 19th January to 9th February 2021. During daily time, 56 hauls, lasting 30 minutes, have been carried out with a GOV bottom trawl. A total of 82 fish species have been collected, determined and... |
| Tipo: Text |
Palavras-chave: North sea; GOV; Beam trawl; MIK; Abundance; Stock assessment. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00691/80333/83418.pdf |
| |
|
|
| Caill-milly, Nathalie; Duclercq, Benoit; Morandeau, Gilles. |
| Between 1980 and 1986, some Arcachon oyster farmers took up breeding the Japanese clam on the foreshore (Robert et Deltreil, 1990). This production was short lived. The steep fall in prices due to economic competition from Spain, Portugal, Italy and Tunisia, predator action such as the trigger fish (Popovsky et al., 1999), added to the significant amount of mortality that occurred in the summer and autumn of 1992 that affected two-thirds of the total stock, led to clam farming being abandoned at the end of the 1980s. In the Arcachon basin, the Japanese clam (Ruditapes philippinarum) population, now natural to the area, has found favourable conditions for development and is expanding rapidly there. This species has been supplanting the local species... |
| Tipo: Text |
Palavras-chave: Ruditapes philippinarum; Veneridae; Popluation structure; Biomass; Stock assessment; Arcachon Bassin; Veneridae; Ruditapes Philippinarum; Bivalvia; Mollusca; Structure Population; Biomasse; Abondance; Evaluation Stock. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/2006/rapport-2218.pdf |
| |
|
| |
| Registros recuperados: 173 | |
|
|
|
