Spatial partitioning of relative fishing mortality and spawning stock biomass of Icelandic cod

Gavin A. Begg*, Gudrun Marteinsdottir

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


Fishing mortality affects demographic characteristics of a population, and is a major determinant in loss of spawners from a fish stock; directly influencing stock productivity and recruitment variability. We investigated the effects of fishing on the composition of the spawning stock of cod (Gadus morhua) in Icelandic waters by partitioning relative fishing mortality and spawning stock biomass (SSB) into finer spatial components than those used previously. Geographic regions of reproductive importance were identified around the country, in contrast to traditional paradigms of cod stock structure in Icelandic waters. SSB and relative fishing mortality were unevenly distributed in waters around Iceland, where gill nets selectively removed larger spawners from inshore waters of the main spawning grounds, whose demographic characteristics were more conducive to progeny survival. Changes in stock structure and demographic characteristics caused by changes in spatially explicit exploitation patterns can significantly affect stock productivity through differential loss of reproductive potential. Our approach of partitioning SSB into finer spatial units than those used previously, enabled a more detailed analysis of the distribution of spawners and exploitation of the Icelandic cod stock, and will enable the development of spatially disaggregated models of total egg production, that in turn may assist in differentiating the inherent variability within stock-recruitment relationships.

Original languageEnglish
Pages (from-to)343-362
Number of pages20
JournalFisheries Research
Issue number3
Publication statusPublished - 3 Jan 2003

Bibliographical note

Funding Information:
We would like to thank the survey leaders, Olafur K. Palsson, Sigfús A. Schopka, and Sólmundur T. Einarsson, as well as, all the cruise leaders and research scientists for collection of the survey data; Lorna Taylor, Gunnar Stefánsson, Asta Gudmundsdottir, and Höskuldur Björnsson for discussions and statistical advice; and two anonymous reviewers for their constructive comments. This study was part of the EU funded project, FAIR-PL98-4122, ‘An operational model of the effects of stock structure and spatio-temporal factors on recruitment (STEREO)’, and was supported by the Icelandic Research Council and the Ministry of Fisheries.

Other keywords

  • Cod
  • Exploitation
  • Fisheries management
  • Gadus morhua
  • Iceland
  • Maternal effects
  • Mortality
  • Population dynamics
  • Recruitment
  • Spatial distribution
  • Spawning composition


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