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| Registros recuperados: 173 | |
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| Hammond, T; Trenkel, Verena. |
| Landings statistics can be lower than true catches because many fish are discarded or landed illegally. Since many discards do not survive, treating landings as true catches can lead to biased stock assessments. This paper proposes treating catch as censored by bounding it below by the landings, L, and above by cL (for scalar c > 1), We demonstrate the approach with a simulation study, using a Schaefer surplus production model. Parameters were estimated in a Bayesian framework with BUGS software using two sets of priors. Both the traditional true-catch method and a survey-and-effort method (which was landings free) performed worse on average than the censored approach, as measured by the Bayes risk associated with estimates of maximum sustainable yield... |
| Tipo: Text |
Palavras-chave: Stock assessment; Misreporting; Discarding; Censored data. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-641.pdf |
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| Hansen, J.E.; Garciarena, A.D.. |
| As part of the research programs performed yearly at the Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP, Mar del Plata, Argentina) some important basic data about the commercial fisheries usually included in internal reports are registered. This formal paper is a review and summary of size and age composition estimates of commercial catches (discards included) of Northern Argentine anchovy (34ºS-41ºS) obtained between 1990-2011. The basic data resulting from the examination of 521 samples from fishing vessels included 62,466 fish length measurements and 26,667 valid age readings from which the corresponding 22 annual age-length keys were built. The annual estimates of the individual total length-total weight relation parameters and of... |
| Tipo: Journal Contribution |
Palavras-chave: Pelagic fisheries; Stock assessment; Commercial fishing; Catch composition; Age composition; Size distribution; Clupeoid fisheries. |
| Ano: 2013 |
URL: http://hdl.handle.net/1834/5502 |
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| Bertignac, Michel; De Pontual, Helene. |
| The results of a pilot tagging study on hake (Merluccius merluccius), conducted in the northern part of the Bay of Biscay in 2002, indicate that growth rates for this stock may be currently underestimated because of biased estimates of age. The impact that such a bias may have on the stock dynamics and the trends of the key population parameters, recruitment, spawning-stock biomass (SSB), and mortality are investigated. Assuming new growth parameters, a new age-length key is derived and used to produce and catch-at-age data and abundance indices, which are then used to assess the stock. Bias in estimating age affects the absolute levels of fishing mortality and stock biomass estimates, and also impacts the trend in SSB. However, trends in fishing mortality... |
| Tipo: Text |
Palavras-chave: Tagging; Stock assessment; Simulation; Management; Growth; European hake; Age estimation. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2824.pdf |
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| 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 |
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| Desprez, M; Ducrotoy, J; Elkaim, B. |
| In this paper, the results collected since 1978 on the cockle (Cerastoderma edule) in the Bay of Somme have been recapitulated. A synthesis is brought up about causes of the bivalve population collapse which was portended as early as 1982 from the animal cinetics study. In order to back up the discussion, the main results dealing with the biology and ecology of the species are recalled in illustrated form. A review of the international literature leads to a comment upon the diagrams. A comparison with data from European estuaries tends to take climatic and oceanic disturbances into account as well as local pollution such as eutrophication which is probable on the littoral of Picardy. |
| Tipo: Text |
Palavras-chave: Clam fisheries; Stock assessment; Recruitment; Population dynamics; Marine mollusks. |
| Ano: 1985 |
URL: http://archimer.ifremer.fr/doc/1985/publication-1783.pdf |
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| Ducrotoy, J; Desprez, M; Elkaim, B. |
| The recent collapse in the landings of cockles (Cerastoderma edule) from the Bay of Somme (France) required to investigate if a change in the environmental factors was liable for the drop of the bivalve populations. This project has led to a preliminary assessment of the situation and has been drawn up from the data collected by the Groupe d'Etude des Milieux Estuariens et Littoraux since 1978. It relies on the survey of the spatio-temporal changes of bio-facies. it is suggested that the impact of changes in sediment characteristics is important as well as competition with species as Pygospio elegans (Polychaeta). The above parameters are assessed as essential in the fluctuations of the cockle numbers but they do not explain entirely the collapse in the... |
| Tipo: Text |
Palavras-chave: Landing statistics; Clam fisheries; Stock assessment; Population dynamics; Marine mollusks. |
| Ano: 1985 |
URL: http://archimer.ifremer.fr/doc/1985/publication-1784.pdf |
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| Góngora, M.E.. |
| This work characterizes the composition and dynamics of the incidental catch in the patagonian shrimp (Pleoticus muelleri) fishery, with special emphasis on the bycatch of common hake (Merlucius hubbsi). The Observer Program coordinated by the Chubut Province (Argentina) and used to monitor the fishery is evaluated. The factors that explain the variability of hake bycatch rates are analyzed, different statistical estimators are evaluated and possible strategies for controlling bycatch are discussed. The study is centered on the double-otter-trawl freezers, responsible for 75 percent of the Argentine shrimp landings. This fleet operates in San Jorge Gulf, in waters under the jurisdiction of the provinces of Chubut and Santa Cruz, and in waters of the... |
| Tipo: Theses and Dissertations |
Palavras-chave: Shrimp fisheries; Stock assessment; Fishery management; By catch; Catch composition. |
| Ano: 2011 |
URL: http://hdl.handle.net/1834/4190 |
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| Registros recuperados: 173 | |
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