Fishery Biology of Northeast Atlantic Squid: An overview

The aims of this project were to improve understanding of the basic life-cycle biology, stock structure, trophic interactions and fisheries exploitation of northeast Atlantic squid, in particular the loliginids Loligo forbesi and Loligo vulgaris. Multivariate analysis of morphometric data and isozyme electrophoresis shows that L. forbesi populations from the coast of mainland Europe are fairly homogeneous, but that those from the Azores are a distinct stock. Loligo forbesi and L. vulgar is are annual species with a peak of breeding in the winter (December-May) throughout the geographical range, and one or more seasonal peaks of recruitment. Loligo are probably batch spawners. Males grow larger than females, mature about 1 month earlier and recruit earlier to the fishery. Sexual maturity occurred at two distinct size classes, more obviously in males than females. Fish, including many commercially important species, and Crustacea, were the dominant prey of Loligo. The incidence of fish in the diet increases with squid size. Squid of all types are eaten by fish, seals, cetaceans and seabirds, although quantitative estimates of consumption by these trophic levels were low. Catches of squid from northeast Atlantic waters increased over the period 1980-1990 but currently supply only a minor component of the European market for squid, the balance being made up by imports. The squid catch in the northern part of the range shows wide fluctuations in abundance by area and by season. The applicability of assessment methods for these stocks is limited by inadequate and inaccurate statistical information, and because nearly all of the catch arises as a by-catch from finfisheries.