Conserving spawning stocks through harvest slot limits and no‐take protected areas

Abstract

The key to the conservation of harvested species is the maintenance of reproductive success. Yet for many marine species large, old, individuals are targeted despite their disproportionate contribution to reproduction. We hypothesized that a combination of no-take marine protected areas (MPAs) and harvest slot limits (maximum and minimum size limits) would result in the conservation of large spawning individuals under heavy harvest. We tested this approach under different harvest intensities with a 2-sex, stage-structured metapopulation model for the Caribbean spiny lobster (Panulirus argus). P. argus is intensively harvested in the Caribbean, and in many localities large, mature individuals no longer exist. No-take MPAs and harvest slot limits combined, rebuilt and maintained large mature individuals even under high harvest pressure. The most conservative model (a 30% MPA and harvest slot limit of 75-105 mm) increased spawner abundance by 5.53E 12 compared with the fishing status quo at the end of 30 years. Spawning stock abundance also increased by 2.76-9.56E 12 individuals at a high harvest intensity over 30 years with MPAs alone. Our results demonstrate the potential of MPAs and harvest slot limits for the conservation of large breeding individuals in some marine and freshwater environments. Decisions on which management strategy best suits a fishery, however, requires balancing what is ecologically desirable with what is economically and socially feasible.

Anthropause shows differential influence of tourism and a no‐take reserve on the abundance and size of two fished species

“…A variety of management options have long been employed for both species, including size and catch restrictions, closed seasons, and gear restrictions (Bush et al, 2006;Caribbean Regional Fisheries Mechanism (CRFM), 2011;Cheung et al, 2013;Waterhouse et al, 2020). Benefits from MPAs have also been shown for both species (Cox & Hunt, 2005;Bernard et al, 2016;Gnanalingam, Gaff & Butler, 2020), despite their differing biology.…”