Effect of environmental conditions on the seasonal and inter-annual variability of small pelagic fish abundance off North-West Africa: The case of both Senegalese sardinella
|Author(s)||Thiaw Modou1, Auger Pierre-Amael2, 3, 4, Ngom Fambaye1, Brochier Timothee1, 5, 6, Faye Saliou1, Diankha Ousmane7, Brehmer Patrice1, 5|
|Affiliation(s)||1 : ISRA, CRODT, Dakar, Senegal.
2 : IRD, Lab Environm Marin, UMR 195, Lemar, Technopole Brest Iroise, Plouzane, France.
3 : Pontificia Univ Catolica Valparaiso, Inst Milenio Oceanog, Valparaiso, Chile.
4 : Pontificia Univ Catolica Valparaiso, Escuela Ciencias Mar, Valparaiso, Chile.
5 : IRD, Lab Environm Marin, UMR 195, Lemar, Dakar, Senegal.
6 : Sorbonne Univ, Univ Paris 06, IRD, UMI 209,UMMISCO, Bondy, France.
7 : Univ Cheikh Anta Diop Dakar UCAD, LPAO SF, ESP, Dakar, Fann, Senegal.
|Source||Fisheries Oceanography (1054-6006) (Wiley), 2017-09 , Vol. 26 , N. 5 , P. 583-601|
|WOS© Times Cited||31|
|Keyword(s)||Climatic change, oceanography, Sardinella aurita, Sardinella maderensis, small pelagic, small-scale fisheries|
|Abstract||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 of sardinella is determined by a strong seasonal pattern and inter-annual fluctuations. The abundance of S.aurita peaked in spring and in autumn, whereas that of S.maderensis peaked in the warm season (July-September). The trend of the sardinella abundance was significantly correlated with the CUI, especially in autumn and spring. Interannual fluctuations of S.maderensis and S.aurita abundance are, respectively, driven by the precocity and the duration of the upwelling season that is attributed to distinct migration patterns. Both sardinella species also respond with a delay of around 4years to the winter NAO index and the autumn CUI, and the AMO index, respectively, both related to migration patterns. The wide variations in sardinella biomass are caused by variations in environmental conditions, which should be considered in the implementation of an ecosystem-based approach in sardinella stocks management.|