Peculiarities of distribution and fishery of pelagic fish species in the autumn-winter period in the area of Mauritania

Abstract

Particular attention is paid to the description of cunene horse mackerel migration which has a determining influence on the fishery nature during this period. As a source material, daily vessel reports (SSDs), database on reconstructed trawling positions of fishing vessels, satellite data on sea surface temperature (SST) and information on length composition of catches according to the SSD data on the assortment of fish production were used. In the period under study, dynamics of the species composition shows a steady increase in the share of cunene horse mackerel in the catches yielded from August to March. The dates for beginning and ending of the migration of cunene horse mackerel and mackerel species associated with it in the waters of Mauritania are determined. The migration of fish from the Moroccan EEZ usually occurs in the interval between the first decade of November and the first decade of December, at the SST in the range of 20,5–22,5 °C. It ends in the period from the third decade of January to the third decade of February, at the SST within the range of 18,0–20,5 °C. Duration of the presence of cunene horse mackerel mass concentrations in the EEZ of Mauritania during the period of the autumn-winter migration fluctuated within 43–91 days averaging 67 days. It is shown that the migration of commercial concentrations occurs over the depths from 50 to 500 m, mainly along the border of the coastal zone prohibited for fishing. Therefore, even minor fluctuations in the channel of concentrations migrating to the east or west radically change the fishing situation. The most efficient fishery in the autumn-winter period is possible from December to January when the maximum daily catch volume and the optimum species composition of catches are noted.