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Modelling the selective effects of fishing on reproductive potential and population structure of squid

Murphy, E.J.; Rodhouse, P.G.; Nolan, C.P.. 1994 Modelling the selective effects of fishing on reproductive potential and population structure of squid. ICES Journal of Marine Science, 51 (3). 299-313. https://doi.org/10.1006/jmsc.1994.1031

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Abstract/Summary

Artificial selection processes associated with harvesting may operate over relatively short time scales in short-lived semelparous species. The ommastrephid squid Illex argentinus on the Patagonian Shelf is the target of a major fishery. Recent work has provided new information on the biological characteristics of squid in this fishery. That information has been utilized in the development of a model of the cohort dynamics and some of the within-seasons selective effects considered. The model results are consistent with earlier data from the shelf fisheries, supporting suggestions that the males nature and migrate earlier towards the spawning grounds than the females. Earlier maturation results in a smaller mean size in the spawning stock, while later maturation results in greater exposure to the fishery and a reduced numbers of individuals surviving to spawn. Under the current fishing regime greater egg production and a larger spermatophoric complex mass for the whole cohort is achieved by relatively late maturation. In general, however, the earlier maturation occurs, the earlier is the peak in total egg production. The within-season pattern of effort expenditure in the fishery can affect not only yield from the fishery but also the reproductive potential of the spawning stock. The management policy adopted for this fishery is likely to be conservative in terms of maintenance of a spawning stock, however, the potential for selective effects is larger and this may affect both yield and reproductive potential. The results are discussed in relation to short- and long-term effects in the fishery and the implications for future research requirements.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1006/jmsc.1994.1031
Programmes: BAS Programmes > Pre 2000 programme
ISSN: 10543139
Additional Keywords: model, squid, population dynamics, reproductive potential, selection
Date made live: 29 Mar 2017 09:50 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/516696

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