The influence of environmental factors and hydrodynamics on the sardine (Sardinapilchardus, Walbaum 1792) abundance in the southern Alboran Sea
2018
Jghab, A. | Vargas-Yáñez, Manuel | Reul, A. | García-Martínez, María del Carmen | Hidalgo, Manuel | Bernal, M. | Benomar, M | Benchoucha, S. | Lamtai, A.
The study of environmental variables and their influence on the small pelagic fish stocks in the Alborán Sea (Western Mediterranean) is asymmetrical being scarce those studies focused on the southern coast if compared to the northern one. In the present work, sardine landings time series from the Moroccan coast of the Alborán Sea from 1981 to 2016 area analyzed together with environmental variables such as Sea Surface Temperature (SST), Sea Surface Salinity (SSS), Surface Chlorophyll-a concentrations and the velocity of the Atlantic Jet flowing into the Mediterranean Sea through the Strait of Gibraltar. Sardine annual catches have decreased from 1981 to 2016 at a rate of -258 t/yr. At the same time, SST and SSS have increased at rates of 0.03 ºC/yr and 0.004 ups/yr, very likely as a result of climate change. Linear models reflect a negative relationship between sardine landings and SST and SSS indicating that the long term changes of the temperature and salinity in the Mediterranean could have a negative impact of the sardine abundance. On an inter-annual time scale, chlorophyll concentrations seem to be positively related to sardine abundances. There is also a clear decrease of the kinetic energy of the AJ inferred from the cross strait sea level difference (SLD). This variable has a great influence (positive correlation) with the sardine landings both at the long term and at the inter annual time scale with higher sardine abundances associated to higher SLD. Linear models in the present work show their ability to reproduce around 60 % of the sardine landings variance.
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