Manuscript On The Effects Of Large Marine Reserves
On The Fisheries For Pacific Coast Groundfishes
Current Status of Accomplishment or Milestone: The paper was published in the 1999 CalCOFI Reports.
Background: Marine reserves are one possible management method that could be implemented to manage the west coast groundfish stocks that are currently in a state of crisis. This paper was originally prepared as an invited paper at a symposium on the use of no-take marine reserves for resource management.
Purpose of Activity/Goal of Project: As the majority of participants in the symposium were pro reserve, the author was assigned the task of looking at marine reserves from a devil's advocate point of view. In particular, the paper addressed the population dynamics of management with marine reserves in relation to claims that annual yields could be increased by such reserves.
Description of Accomplishment and Significant Results: The analyses presented in the paper suggest that, with reserves of 35% or greater of a species habitat, current yields can only be obtained with a considerable increase in total fishing effort and a very large increase in the fishing mortality rates in the areas open to fishing. For west coast groundfish this implies a large increase in the trawling rate, and probably associated ecological damage, in the exploited area. Even if it were desirable to manage an individual species with large marine reserves the concept gets into difficulty when applied to the West Coast trawl fishery, which is based on many species each with a different habitat. In addition marine reserve established for overexploited groundfish species would provides little real protection for migratory species such as Pacific hake, but they may greatly increase the cost of fishing for these species. Other potential undesirable effects may include considerable decreases in recruitment, depending upon the source of density-dependence in recruitment, and fisheries that are based on very few year-classes.
Significance of Accomplishment (e.g., to the Center, to Management, and to NMFS Strategic plan Goals): The analysis indicates that the use of large marine reserves, that is reserves that occupy more than 25% of a species total habitat, are very unlikely to achieve the yields of an optimally managed fishery. However, it must be noted that the effects of marine reserves are highly dependent upon the size of the reserves and this dependence is highly non-linear. Therefore reserves in the 5-10% range when accompanied with a 5-10% reduction in optimum yields could be a valid precautionary approach that could achieve significant benefits associated with species diversity, habitat protection and research opportunities that are unlikely be achieved if the entire habitat of a species is exploited.
Key Contact: Richard Parrish (831-648-9033, rparrish@pfeg.noaa.gov)