FISHERY BIOLOGY OF NORTHEAST ATLANTIC SQUID - AN OVERVIEW

The aims of this project were to improve understanding of the basic li fe-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 morphome tric data and isozyme electrophoresis shows that L. forbesi population s from the coast of mainland Europe are fairly homogeneous, but that t hose from the Azores are a distinct stock. Loligo forbesi and L. vulga r is are annual species with a peak of breeding in the winter (Decembe r-May) throughout the geographical range, and one or more seasonal pea ks of recruitment. Loligo are probably batch spawners. Males grow larg er than females, mature about 1 month earlier and recruit earlier to t he fishery. Sexual maturity occurred at two distinct size classes, mor e obviously in males than females. Fish, including many commercially i mportant 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 quan titative estimates of consumption by these trophic levels were low. Ca tches of squid from northeast Atlantic waters increased over the perio d 1980-1990 but currently supply only a minor component of the Europea n market for squid, the balance being made up by imports. The squid ca tch in the northern part of the range shows wide fluctuations in abund ance by area and by season. The applicability of assessment methods fo r these stocks is limited by inadequate and inaccurate statistical inf ormation, and because nearly all of the catch arises as a by-catch fro m finfisheries.