Abstract

Fisheries that target spawning aggregations are often perceived as inherently unsustainable, with the assumption that even moderate exploitation of spawning fish will result in overfishing and marked population declines. Consequently, spawning aggregations may be fully protected from fishing without an evaluation of whether such restrictions are necessary for sustainability. We designed a parsimonious, non-spatial model to evaluate the effects of seven time-closure scenarios on egg-production-per-recruit (reproductive capacity; a conservation metric) and yield-per-recruit (exploitable biomass; a fisheries metric) of the Gulf Corvina, Cynoscion othonopterus, a vulnerable marine fish that is heavily exploited at its only known spawning grounds in northwest Mexico. Results of the model indicated that exploitable biomass was enhanced in five of the seven time-closure scenarios. Moreover, three scenarios offered a reasonable compromise between reproductive capacity and exploitable biomass, in which measurable increases in egg-production-per-recruit (16-42%) were accompanied by proportional increases in yield-per-recruit (33-44%) that resulted in a sustainable fishery. Our findings suggest that the implementation of specific time closures during the spawning season (e.g. closures during the peak spawning day each tide) can benefit both the conservation of the Gulf Corvina and its fishery through the sustainable exploitation of spawning aggregations. Results of the study also illustrate how detailed information on spawning and fishing activities can be directly incorporated into stock assessments and used for management strategy evaluations of aggregation fisheries.

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