Contrasted optimal environmental windows for both sardinella species in Senegalese waters
2018
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 the sea surface temperature for S.aurita and S.maderensis, respectively. We report that recruitment success of S.aurita and S.maderensis are associated with distinct ranges of sea surface temperature, upwelling intensity, wind-induced turbulence, concentration of chlorophyll-a and north Atlantic oscillation index. Considering food security and socio-economic importance of both stocks, we recommend that consideration is given to the environmental variability in the small pelagic fish national management plans, particularly in the context of climate change.
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