The relationship between Sardinella aurita landings and the environmental factors in Moroccan waters (21°-26°N)

Baali A., Charouki N., Manchih K., Bessa I., Elqoraychy I., Elqendouci M., Amenzoui K., Yahyaoui A.

Published date: February 2019
Volume: 43
Number: 1
Pagination: 51-59
Publisher: Société Française d'Ichtyologie
doi: https://doi.org/10.26028/cybium/2019-431-005
Abstract

The objective of this study is to assess the effects of environmental variations on the abundance of the round sardinella (Sardinella aurita, Valenciennes, 1847) in Moroccan waters (21°-26°N) using generalized additive models. The monthly variability of Sardinella aurita abundance in the south of Morocco is investigated using sea surface temperature (SST), upwelling index (UI) and chlorophyll-a (Chl-a) concentration from Global ARMOR3D L4 product, ESA Ocean Colour CCI and AquaMODIS satellite data between 2009 and 2016. The results show that there is a significant correlation between fish landings, SST and Chl-a, especially at latitude 22°N. Concerning the UI, the correlation is positive and not significant at latitudes 21 and 22°N. The relationship between the environmental parameters indicate that there is a high and significant correlation between the SST and Chl-a at latitude 22°N. Using generalized additive models, it was found that environmental parameters (SST, Chl-a, and UI) in the latitude 22°N played a major role in explaining differences in monthly landings for S. aurita (65.1% deviance explained). The high abundance of S. aurita, observed in autumn, is due to the adequate environmental condition in the south of Morocco, which leads to the migration of this species from Mauritanian to Moroccan waters.

Keywords: Chlorophyll-a - Fish landings - Moroccan waters - Sardinella aurita - Sea surface temperature - Upwelling index
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