Seasonal evolution of small pelagic fish landings index in relation to oceanographic variables in the Canary Islands (Spain)

Abstract

The main small pelagic fish species targeted by fishers in the Canary Islands are, in order of importance in landings: the Atlantic chub mackerel Scomber colias, horse mackerels Trachurus spp, the European pilchard Sardina pilchardus and sardinella Sardinella spp. In this study we evaluate seasonal relationships between selected oceanographic variables and these landings. Monthly values of Sea Surface Temperature (SST, °C), SST anomaly (SSTA, °C) and chlorophyll a concentration (Chl-a, mg/m3) were obtained for the study area between January 2009 and December 2016, and compared with the seasonal evolution of a landing index compiled from official sale notes. Non-parametric multivariate analyses enabled assessment of the seasonal variation of the catches over the study period. Despite strong interannual variability, different seasonal patterns were observed for each species, with cooler seasons (lower SST and higher Chl-a) characterized by catches of medium-sized species (S. colias and Trachurus spp), and warmer seasons (higher SST and lower Chl-a) by the smaller-sized species (S. pilchardus and Sardinella spp). SSTA appears to explain the unusual seasonal landings.