Conceptual Issues Relevant to Marine Harvest Refuges: Examples from Temperate Reef Fishes

TLDR

The size, number, and distribution of marine fish refuges must match harvest rates and larval recruitment dynamics, which are governed by intrinsic reproductive traits, extrinsic environmental factors, and the spatial extent of larval replenishment, making proper refuge design critical for sustaining fisheries. The study proposes evaluation criteria that assess a refuge’s capacity to sustain high larval production of target species and to replenish harvested populations at a level sufficient to support a predetermined harvesting rate.

Abstract

The size of a refuge needed to sustain a fishery depends on the harvest and on the rate at which both refuge and harvested populations supply new recruits to the fishery. Recruitment rates are determined by larval production, and both intrinsic (e.g., reproductive mode, larval behavior) and extrinsic (e.g., predation, resource availability, currents) factors that influence the geographic range over which a refuge can effectively supply recruits. The size, number, and distribution of refuges depend on patterns of larval replenishment. Since resource requirements of fish often change with ontogeny and reproductive condition, refuges may need to include a wide variety of habitats. Larval production by refuges may be enhanced by multispecies management that provides protection for or allows harvesting of nontarget species. Additionally, protection may be needed for resources located outside refuges that enhance recruitment to harvested populations. Because improperly designed refuges may endanger a fishery by providing a false sense of protection, determining the effectiveness of a refuge is of utmost importance. Evaluation criteria should include the ability of a refuge to maintain high larval production of target species and to contribute to replenishment of harvested populations at a level sufficient to sustain a predetermined harvesting rate.