Spawning of anchovy Engraulis encrasicolus in the Northwestern Mediterranean relative to hydrographic features in the region

Abstract

The present study furnishes conclusive evidence for the existence of latitudinal differences m the duration of anchovy spawning related to temperature cycle and hydrographic features; 2 main spawmng areas were found, one off northern and another off southern Catalonia (NW Mediterranean, NE Spain). Total egg production was similar in the 2 spawning areas and even somewhat higher m the northern area, where the spawning cycle was shorter (ca 2 mo). The areas of highest egg abundance were located relatively far offshore, between 10 and 30 miles from the coast, spanning a very broad range of bottom depths, from 50 to 1000 m. The presence of a shelf-slope front of variable intensity running along the entire coast (Font et al. 1988) suggests that anchovy take advantage of the productivity associated with the front for reproductive purposes, particularly since the front is the most important enrichment phenomenon in the region during summer, the time of maximum spawning (Estrada & Margalef 1988). In addition, the distribution of spawning activity brings to light its association with the zones of influence of the outflows of 2 large rivers, the Rh6ne and the Ebro. On the whole, the reproductive behaviour of Engraulis encrasicolusm the Northwestern Mediterranean takes advantage of the most favourable conditions to ensure the success of early life stages in a region in which enrichment phenomena are more limited than those described for other clupeoid species