Marine reserves can improve the scientific basis for fishery management decisionmaking by offering scientists ecological benchmarks against which fishing impacts can be measured, as well as baseline data on the age, growth, life history parameters and ecological interactions of marine communities. Marine reserves are difficult to properly design and site. Basic information on the ranges, life history parameters, and habitat requirements of fish species and on the ocean currents, patterns of larval dispersal, and location of critical habitat within regional marine systems is extremely scarce. This makes it difficult to determine the optimum size and location of marine reserves and to predict direct fishery benefits in advance. Many fear that the replenishment benefits provided by poorly designed reserves would not outweigh the costs of displacing fishermen.
Marine reserves displace fishermen.
Closing fishing grounds will displace some fishermen. In addition, displacement is likely to increase competition and allocation battles in fishing grounds outside reserve areas and contribute to overcapacity problems in fisheries that are not protected under a limited access system. Marine reserves offer incomplete protection. Marine reserves cannot protect fish from the effects of natural environmental variability or other activities that are out of the hands of fishery managers. In this way, even perfectly sited reserves involve a certain degree of risk.