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| Brochier, Timothee; Auger, Pierre-amael; Pecquerie, Laure; Machu, Eric; Capet, Xavier; Thiaw, Modou; Mbaye, Baye Cheikh; Braham, Cheikh-baye; Ettahiri, Omar; Charouki, Najib; Sene, Ousseynou Ndaw; Werner, Francisco; Brehmer, Patrice. |
| Small pelagic fish (SPF) species are heavily exploited in eastern boundary upwelling systems (EBUS) as their transformation products are increasingly used in the world food chain. Management relies on regular monitoring, but there is a lack of robust theories for the emergence of the populations’ traits and their evolution in highly variable environments. This work aims to address existing knowledge gaps by combining physical and biogeochemical modelling with an individual life-cycle based model applied to round sardinella (Sardinella aurita) off northwest Africa, a key species for regional food security. Our approach focused on the processes responsible for seasonal migrations, spatio-temporal size-structure, and interannual biomass fluctuations.... |
| Tipo: Text |
Palavras-chave: Small pelagic fish; Sardinella aurita; Fish migration; Eastern boundary upwelling system; Individual based biophysical models; Dynamic energy budget. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00433/54433/56088.pdf |
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| Ba, Kamarel; Thiaw, Modou; Fall, Massal; Thiam, Ndiaga; Meissa, Beyah; Jouffre, Didier; Thiaw, Omar Thiom; Gascuel, Didier. |
| For the first time in Senegal, assessments based on both stochastic and deterministic production models were used to draw a global diagnosis of the fishing impact on coastal demersal stocks. Based one national fisheries databases and scientific trawl surveys data: (i) trends in landings since 1971 were examined, (ii) abundance indices of 10 stocks were estimated using linear models fitted to surveys data and commercial catch per unit efforts, and (iii) stock assessments were carried out using pseudo-equilibrium Fox and Pella-Tomlinson models and a Biomass dynamic production model fitted in a Bayesian framework to abundance indices. Most stocks have seen their abundance sharply declining over time. All stocks combined, results of stock assessments suggest a... |
| Tipo: Text |
Palavras-chave: Coastal demersal species; Delta-GLM models; Surplus production models; Bayesian approach; Overexploitation; West Africa. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00626/73792/74929.pdf |
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| Diankha, Ousmane; Demarcq, Herve; Fall, Massal; Thiao, Djiga; Thiaw, Modou; Sow, Bamol Ali; Gaye, Amadou Thierno; Brehmer, Patrice. |
| This study investigated variations of landings of two key species, Sardinella aurita and Sardinella maderensis, in Senegalese waters over a ten-year period (2004-2013). Using generalized additive models, it was found that fishing gear played a major role in explaining differences in monthly landings for both species (51-71% deviance explained). Its effect was more significant in the southern part of Senegal. Fishing effort (number of trips) accounted only for 4-18% of variability in landings. Purse seine (PS) fishing was the most important contributor to the landings of both species. In addition, in the southern area, surrounding gillnet fishing was also important for S. maderensis. Modeling results showed that the relationship between monthly effort and... |
| Tipo: Text |
Palavras-chave: Effects of fishing; Generalized additive model; Sardinella aurita; Sardinella maderensis; Purse seine; Surrounding gillnet; Senegal. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00616/72808/72585.pdf |
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| Ba, Kamarel; Thiaw, Modou; Lazar, Najih; Sarr, Alassane; Brochier, Timothee; Ndiaye, Ismaila; Faye, Alioune; Sadio, Oumar; Panfili, Jacques; Thiaw, Omar Thiom; Brehmer, Patrice. |
| The stock of the Senegalese flat sardinella, Sardinella maderensis, is highly exploited in Senegal, West Africa. Its growth and reproduction parameters are key biological indicators for improving fisheries management. This study reviewed these parameters using landing data from small-scale fisheries in Senegal and literature information dated back more than 25 years. Age was estimated using length-frequency data to calculate growth parameters and assess the growth performance index. With global climate change there has been an increase in the average sea surface temperature along the Senegalese coast but the length-weight parameters, sex ratio, size at first sexual maturity, period of reproduction and condition factor of S. maderensis have not changed... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00616/72851/72887.pdf |
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| Diankha, Ousmane; Ba, Aliou; Brehmer, Patrice; Brochier, Timothee; Sow, Bamol Ali; Thiaw, Modou; Gaye, Amadou Thierno; Ngom, Fambaye; Demarcq, Herve. |
| We investigate Sardinella aurita and Sardinella maderensis recruitment success relative to the variability of oceanographic conditions in Senegalese waters using generalized additive models (GAM). Results show that recruitment of both species is marked by a strong intra-annual (seasonal) variation with minimum and maximum in winter and summer, respectively. Their interannual variations are synchronous until 2006 (recruitment decreasing), while from 2007 there is no synchrony. The model developed shows that sardinella recruitment variability is closely related to the tested environmental variables in the study area. However, the key environmental variables influencing the recruitment success are different for both species: the Coastal Upwelling Index and... |
| Tipo: Text |
Palavras-chave: Recruitment success; Sardinella aurita; Sardinella maderensis; Upwelling; West Africa. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00611/72299/71189.pdf |
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| Thiaw, Modou; Auger, Pierre-amael; Ngom, Fambaye; Brochier, Timothee; Faye, Saliou; Diankha, Ousmane; Brehmer, Patrice. |
| The objective of this study was to assess the effect of environmental variations on the abundance of Sardinella aurita and Sardinella maderensis in Senegalese waters in the upwelling system. Monthly data indicating the abundance of sardinella were first estimated from commercial statistics, using Generalized Linear Model from 1966 to 2011. Abundance indices (AIs) were then compared with environmental indices, at the local scale, a Coastal Upwelling Index (CUI) and a coastal Sea Surface Temperature (SST) index, and on a large scale, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Multivariate El Nino Southern Oscillation Index (MEI), using correlations and times series analyses. The results showed that the abundance... |
| Tipo: Text |
Palavras-chave: Climatic change; Oceanography; Sardinella aurita; Sardinella maderensis; Small pelagic; Small-scale fisheries. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00611/72307/71213.pdf |
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