Disentangling the effects of fishing and environmental forcing on demographic variation in an exploited species

Gaines, Steven D.; Cornejo-Donoso, Jorge; Teck, Sarah J.; Caselle, Jennifer E.; Shears, Nick T.; Hamilton, Scott L.; Lorda, Julio; Bell, Tom W.

Abstract

Species targeted by fishing often recover in abundance and size within marine protected areas (MPAs) resulting in increased reproductive potential. However, in some situations, concomitant changes in the abundance of predators, competitors, or prey within MPAs, or strong gradients in the surrounding environmental seascape may counteract the purported benefits making it more difficult to predict how species will respond to protection. We used a network of MPAs in California, spanning a large temperature gradient, to investigate the drivers of demographic variability in the commercially important red sea urchin Mesocentrotus franciscanus. We investigated how demographic metrics varied geographically in response to protection, temperature, and the main sea urchin resource, the giant kelp Macrocystis pyrifera. We found significant conservation benefits to this fished sea urchin within MPAs designated six years prior to the beginning of this study. Within MPAs, red sea urchins were generally larger resulting in greater adult biomass density and reproductive biomass density. In addition, kelp density was an important explanatory variable of all red sea urchin demographic traits examined (adult size, gonadosomatic index [GSI], density, adult biomass density, and reproductive biomass density). Kelp density was positively correlated with red sea urchin GSI and adult size, but the relationships with density, adult biomass density, and reproductive biomass density were complex and the directionality changed depending on the region (or environmental setting) examined. Our results demonstrate that kelp, red sea urchin reproduction, and the effects of spatial management on demographic processes are tightly coupled with the oceanographic regime. (C) 2017 Elsevier Ltd. All rights reserved.

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Título según WOS: ID WOS:000404308600054 Not found in local WOS DB
Título de la Revista: BIOLOGICAL CONSERVATION
Volumen: 209
Editorial: ELSEVIER SCI LTD
Fecha de publicación: 2017
Página de inicio: 488
Página final: 498
DOI:

10.1016/j.biocon.2017.03.014

Notas: ISI