Publication Abstract

Evaluating management strategies for the thornback ray Raja clavata: Are marine protected areas better than traditional fisheries management?

Evaluating management strategies for the thornback ray Raja clavata: Are marine protected areas better than traditional fisheries management?

Jessica Wiegand, Nick Dulvy & Ewan Hunter

Globally many fisheries are in decline, resulting in calls for the development of marine protected areas to sustain fisheries and protect biodiversity. However, there is some resistance to the implementation of closed areas as they restrict the size of fishing grounds. The relative utility of closed areas for ensuring fisheries yield and biodiversity protection must therefore be considered alongside other management measures. 

Both yield and distribution of the thornback ray (Raja clavata) have declined substantially throughout the North Sea. The aim of this research was to assess the efficacy of management strategies for halting and reversing the current population decline, and to estimate the consequences for the fishery yield. Using parameters from recent research, a deterministic, density-independent matrix model was developed to evaluate the effect of introducing the management strategies of either a seasonal closure of the Thames Estuary or landing size restrictions.

Using this model, both closed areas and specified length restrictions resulted in a sustained population, but the closed area also resulted in greater reductions in yield. A closed area would also restrict the sole fishery within the Estuary, and would involve greater cost for implementation and policing. A more traditional approach using existing frameworks to apply landing size restrictions may, therefore, be better suited to reverse the decline of the thornback ray population.

Reference

J. Wiegand, N. Dulvy* & E. Hunter* (2006) Evaluating management strategies for the thornback ray Raja clavata: Are marine protected areas better than traditional fisheries management? European Elasmobranch Association, 10th Annual Science Meeting, Hamburg, 10-12th November 2006

http://www.eulasmo.org/do_download.asp?did=30134

J. Wiegand, N. Dulvy* & E. Hunter*

European Elasmobranch Association, 10th Annual Science Meeting, Hamburg, 10-12th November 2006