Skip to main content

Do North Sea cod (Gadus morhua) fisheries maintain high catch rates at low stock size?

Buy Article:

$50.00 plus tax (Refund Policy)

Abstract:

This study presents an investigation of the relationship between stock size of North Sea cod (Gadus morhua) and catch rates in seven commercial fishing fleets. The shape of the relationship was estimated using a new model allowing both density-dependent changes in catchability and bias in the assessment biomass estimates. Catchability in fisheries targeting a mixed species composition either remained constant or decreased with decreasing stock size, whereas catchability in targeted cod fisheries increased with decreasing stock size. However, even in the cases where catchability increased, the change was insufficient to compensate for the decrease in stock size, and catch rates of all fleets decreased. Two factors that could lead to nonconstant catchability were investigated: (i) the presence of a decoupling between stock size and density in high-density areas and (ii) the presence of concurrent shifts in the spatial distribution of the cod stock and the cod fishery. No evidence of the former was found, but there was a northern shift in the spatial distribution of both effort and the cod stock.

Notre travail étudie la relation entre la taille du stock de morues (Gadus morhua) de la mer du Nord et les taux de capture de sept flottes de pêche commerciale. La forme de la relation a été estimée à l’aide d’un nouveau modèle qui tient compte des changements de capturabilité dépendants de la densité et d’erreurs dans les évaluations des estimations de biomasse. Dans les pêches commerciales qui ciblent un mélange d’espèces, la capturabilité reste constante ou diminue avec le déclin de la taille du stock, alors que, dans les pêches qui ciblent la morue, elle augmente lorsque la taille du stock diminue. Cependant, même dans les cas d’augmentation de la capturabilité, ce changement ne suffit pas à compenser le déclin de la taille du stock; les taux de capture des toutes les flottes diminuent donc. Nous avons examiné deux facteurs qui pourraient expliquer pourquoi la capturabilité ne reste pas constante: (i) soit l’existence d’un découplage entre la taille du stock et la densité dans les zones de forte densité et (ii) la présence de déplacements concomitants des répartitions spatiales du stock de morues et de la pêche commerciale à la morue. Nous ne trouvons aucune indication de l’existence du premier facteur, mais il y a un déplacement vers le nord de la répartition de l’effort de pêche et de celle du stock de morues.

Document Type: Research Article

Publication date: 2008-09-01

More about this publication?
  • Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Terms & Conditions
  • Sample Issue
  • Reprints & Permissions
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more