Length and recruitment analysis of small pelagic off the Canary Islands

Abstract

Hypothetical geographical segregation by size in the small pelagic populations was studied using a spatial-temporal analysis of mean lengths. Furthermore, to detect the recruitment season and their possible relationship with the satellite-derived sea-surface temperature (SST) and sea surface temperature anomalies (SSTA) values, a fortnightly analysis of the percentage of juveniles in the catches 2005–2006 was carried out. Individuals of mackerel (Scomber japonicus Houttuyn, 1782) smaller than 16 cm, horse mackerel (Trachurus picturatus Bowdich, 1825) and round sardinella (Sardinella aurita Valenciennes, 1847), and sardine (Sardina pilchardus Walbaum, 1792) smaller than 12 cm were used in this analysis. Mean SST by month and oscillations of SSTA data during 2005 and 2006 were used. No evidence of segregation by size in the population was found. However, the smallest individuals of mackerel, round sardinella and sardine were caught in the northern area of Tenerife, and the mean length of mackerel and horse mackerel were greater in Gran Canaria than Tenerife. It was observed along the period studied that similar SSTA values could be favourable for the recruitment of horse mackerel, round sardinella and sardine. In the case of mackerel no pattern was found. A summary of possible recruitment seasons for these sp ecies in the Canaries waters is presented.