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Fishery potential of North Eastern Atlantic squid stocks

Objective

The general significance of the cephalopod biomass and the uncertainties surrounding their life cycles and in predicting the location and density of the population justify a new international programme of research on species of direct relevance to EC countries. Since these populations have wide latitudinal distribution and major migratory cycles may be involved, these fishery questions can only be tackled through multinational cooperative research. The project will improve understanding of the basic life cycle biology of the loliginid squid in the north-eastern Atlantic area. Stock characteristics will be defined and preliminary quantitative estimates made of their fishery potential.
A study has been carried out into the basic life cycle biology, stock structure, trophic interactions and fisheries exploitation of squid from the northeast Atlantic. Target species were the loliginids Loligo forbesi, present throughout the geographical range of the study, and L vulgaris from the southern area. Additional information was obtained on Alloteuthis subulata and the ommastrephids Todaropsis eblanae and Illex coindetti.

The population size structure of Loligo is complex and unstable. Size and age are not consistently related, consequently length based assessment methods are not generally applicable. Multivariate analysis of morphometrical data, and isozyme electrophoresis, shows that L forbesi populations from the coastal waters of mainland Europe are rather homogeneous, but that those from the Azores are a distinct stock. L forbesi and L vulgaris are annual species with a peak of seasonal maturity and breeding in the winter (December-May) throughout the geographical range. Sexual maturity occurred at 2 distinct size classes, more obviously in males than females. This was not explained as different ages at maturity but suggested alternative growth rates perhaps arising genotypically, or from different migratory strategies or ecological conditions. Males grow larger than females, mature about 1 month earlier and recruit earlier to the fishery. Female fecundity estimates vary between 1000-23000 eggs but are not strongly related to body size. Egg size frequency distributions suggest a protracted, batch spawning mode of egg laying. There is seasonal recruitment to the fishery but in some areas 2 periods of recruitment may not be compatible with the timing of breeding. Fish, including many commercially important species were the dominant prey of Loligo. Squid of all types are eaten by fish, seals, cetaceans and seabirds, although quantitative estimates of consumption by these trophic levels were low.

Currently catches from northeastern Atlantic waters supply only a minor component of the European market for squid. 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 bycatch from finfisheries. Potential for increasing the catch and applying possible management methods lies in placing greater emphasis on developing directed fishing by alternative fishing methods, or by selected area and season. A new collaborative European project to obtain more information in cephalopod fisheries in the northeast Atlantic has started.
A sampling programme covering the full latitudinal range and involving 3 partner EC nations will be undertaken by market sampling, from commercial boats and markets, together with ancillary samples from research vessel cruises and gut content analysis of selected marine predators. There will be comparative trials of fishing gear and a preliminary economic analysis.

Measurements and assessments of key biological characteristics will be carried out simultaneously across the survey range using methods agreed and harmonised between the collaborating institutions. Priority will be given to morphometrical measurements for: stock identification; population structure; and reproductive condition, seasonality and fecundity. Indices for recruitment and stock size will be attempted. The overall aim is to provide the basis for multinational management of these increasingly valuable resources which may be replacing certain conventional fish.

The principal target species will be Loligo forbesi (Loliginidae) whose distribution in the eastern Atlantic extends from about 20 degrees north to 63 degrees north. Data on other cephalopod species within this range, especially Loligo vulgaris, and also Alloteuthis subulata, Todaropsis eblanae, Todarodes sagittatus and Ommastrephes bartrami will be included.

Topic(s)

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Call for proposal

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Funding Scheme

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Coordinator

University of Aberdeen
EU contribution
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Address
2 Tillydrone Avenue
AB9 2TN Aberdeen
United Kingdom

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Participants (3)