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ProjectLectures notes. AdriaMed Training Course on Fish Population Dynamics and Stock Assessment. - AdriaMed Technical Documents 8
Split, 10-29 September 2001
2001Also available in:
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Book (series)Interregional workshop on the management of shared stocks and implementation of the ecosystem approach to fisheries within the framework of the EAF-Nansen Programme, Dakar, Senegal 24–26 April 2018 / Atelier interrégional sur la gestion des stocks partagés et la mise en oeuvre de l'approche écosystémique des pêches dans le cadre du Programme EAF-Nansen, Dakar, Sénégal 24-26 avril 2018 2020
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No results found.An interregional workshop on the management of shared stocks and implementation of an ecosystem approach to fisheries within the framework of the EAF-Nansen Programme was held in Dakar, Senegal from 24 to 26 April 2018. The objective of the workshop was to examine with the representatives of partner institutions and principal initiatives the current situation and related activities pertaining to shared stocks by identifying the needs and opportunities to support the management of fisheries exploiting shared stocks within the framework of the EAF-Nansen Programme. Un atelier interrégional sur la gestion des stocks partagés et la mise en œuvre de l'approche écosystémique des pêches dans le cadre du Programme EAF-Nansen s’est tenu à Dakar, Sénégal du 24 au 26 avril 2018. Les objectifs de l’atelier étaient d’examiner avec les représentants des institutions et principales initiatives partenaires la situation actuelle et les activités connexes relatives aux stocks partagés en identifiant les besoins et d’identifier les opportunités d’appui à la gestion des pêcheries qui exploitent les stocks partagés dans le cadre du Programme EAF-Nansen. -
MeetingExploratory stock assessment of the striped marlin (Tetrapturus audax) caught in the Indian Ocean as calculated using a state-space biomass dynamic model 2013
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No results found.Although white marlin is not a target large commercial longline tu boats, it is often a bycacth. There is little information on stock structure but it is assumed that the one unique stock in the Indic Ocean is the most probable hypothesis. The available data is limited to catch and catch rates. Usually the quality of the data concerning bycatch species is not high, hence it is difficult to achieve success running stock assessment models. In this paper a potentially useful Bayesian version of sta te-space biomass dymic models (Fox and Schaefer types) are used in an attempt to assess the status of the white marlin stock of the Indic Ocean. Results are compared to conventiol versions in which only the observatiol error is considered. Calculations were based on estimations of total catch and on standardized catch rates as estimated based on Japan database. In this and in his companion paper (IOTC2013- WPB11-25) the likelihood function was based on log-normal density distributions. Monte Car lo Markov Chains are used to calculate the posterior sample. Three chains starting with different parameters estimations were calculated. The first 50000 samples of each chain were discarded (burnin), and the next 50000 samples were sliced resulting in a fil sample with size equal to 1000. Convergence of the chains was assessed using Gelman-Rubin diagnostics. Most of state-space models have converged, but not the observatiol error models. The exception among the observatiol error models was the Fox type as calculated with a non- informative prior. The state-space models are not biased, but the observatiol error are. The striped marlin database is not very informative, hence the uncertainties on the estimations were very high. The state-space model estimations were also very sensitive to choices about priors. More investigation is needed on the behavior of state-space models when the data is not that informative.
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