Spillover of spiny lobsters Palinurus elephas from a marine reserve to an adjoining fishery

Abstract

We investigate the effects of the Columbretes Islands Marine Reserve (CIMR, Western Mediterranean) on the adjacent Palinurus elephas (Fabricius, 1787) fishery. After 9 to 12 yr of no-take protection there was a gradient of lobster density from the interior of the reserve up to a distance of about 4 km from its boundary. Catch and effort data were collected onboard commercial fishing boats in the fishery adjacent to the CIMR, and combined with catch per unit effort (CPUE) data from monitoring surveys conducted annually inside the reserve. Generalized additive (GAM) and linear (GLM) models were employed to examine the relationships of CPUE and catch per unit area (CPUA) as a function of distance to the reserve boundary. CPUE showed a significant non-linear decline with distance from the centre of the reserve, with a depression at the boundary followed by a plateau. This depression was caused by local depletion associated with concentration of fishing effort at the reserve boundary, while the plateau suggests that lobster export from the reserve is sufficient to maintain stable catch rates up to 1500 m from the boundary. Commercial catch and effort data were combined to estimate CPUA, which declined linearly with distance from the reserve. Analysis of recaptures of lobsters tagged and released inside the reserve indicates that the density gradient is caused by lobsters emigrating from the reserve.

Spillover from marine reserves and the replenishment of fished stocks

“…The expectation that spillover from marine reserves will produce abundance gradients with distance from the reserve, with a shape that depends on species mobility and catch rates, was first described over a decade ago (Rakitin & Kramer 1996) and later refined and modelled (Kaunda-Arara & Rose 2004; Goni et al 2006). We expanded on these previous modelfitting approaches and estimated spillover by fitting three model forms (exponential decay, Eq.…”

“…For Barbados Reserve (Rakitin & Kramer 1996), we used catch rather than density data as density gradients do not always reflect true spillover patterns (as discussed below), but we report both measures in Appendix 1 (see supplementary material at URL http://www.ncl.ac.uk/ icef/EC_Supplement.htm) to help illustrate this point. Finally, for Columbretes Reserve (Goni et al 2006), we used catch per unit effort (CPUE) rather than catch per unit area (CPUA) data because the former were measured both inside and outside the reserve while the latter were only measured outside the reserve, and thus model fits were more accurate (and conservative) with CPUE data.…”

Effects of habitat on spillover from marine protected areas to artisanal fisheries

“…However, only a few studies have experimentally tested for spillover through increased captures in adjacent fished areas, often along density gradients: Barbados (Rakitin & Kramer 1996), Kenya (McClanahan & Mangi 2000, Kaunda-Arara & Rose 2004 and Apo Island in the Philippines (Abesamis & Russ 2005). In the Mediterranean, few data are available to assess the value of MPAs as a source of biomass to surrounding fisheries (Goñi et al 2006).…”

Spatial patterns and movements of red king and Tanner crabs: implications for the design of marine protected areas

“…Although changes in size and density of fishes have been demonstrated within many MPAs, fisheries enhancement relies on the export of larvae or spillover of juveniles or adults to surrounding areas. Because testing for export is difficult (Sale et al 2005), only a few studies have examined these effects (Abesamis & Russ 2005, Alcala et al 2005, Goñi et al 2006. In general, guidelines for designing effective MPAs for fisheries enhancement are lacking (Sale et al 2005).…”