Effects of Artisanal Fishing on Marine Communities in the Galápagos Islands

Abstract

The Galápagos Islands harbor some of the least impacted marine ecosystems in the tropics, but there are indications that local artisanal fishing is affecting exploited marine communities. To quantify these effects, I sampled communities of fishes and sea urchins at a number of heavily fished and lightly fished sites throughout the central islands of the archipelago. Sites were selected based on information collected as part of a local fisheries monitoring study and standardized across a number of abiotic factors. Abundance and biomass of the primary target species were significantly lower in the heavily fished sites than in the lightly fished sites. Community structure also differed between heavily and lightly fished sites. Cluster analyses of the full community of fishes and a subset of nontarget fishes revealed that sites within a treatment were more similar to one another than sites between treatments. Herbivorous fishes tended to be lower in abundance and sea urchins tended to be higher in abundance in heavily fished sites, but these differences were not significant. My results are encouraging in that the direct effects of artisanal fishing are limited to the primary target species, which probably results from a high specificity of fishing gear. The differences in community structure, however, suggest that artisanal fishing also has cascading effects on noncommercial species throughout the community. An improved understanding of important ecological interactions, increased ecological and fishery monitoring, and effective precautionary management are needed to ensure that human effects in these waters remain minimal.

Rapid Effects of Marine Reserves via Larval Dispersal

“…Although commonly considered to be relatively benign compared to industrialized fisheries, increasing evidence from around the world suggests otherwise. Even at relatively low fishing intensities, artisanal fishing has been shown to strongly reduce populations and biomass of targeted species on coral reefs in the Indo-Pacific [52][53][54], eastern Pacific [55], and the Caribbean [18]. Fishermen tend to target and directly reduce populations of large-bodied fishes that are typically longer lived, mature more slowly than smaller ones, and often form spawning aggregations, all of which increase their vulnerability to overfishing [56][57][58][59][60].…”

Cascading effects of fishing on Galapagos rocky reef communities: reanalysis using corrected data

“…Fishing has strongly altered the biomass and size distribution of fisheries species in parts of the Galapagos Marine Reserve (GMR) (Ruttenberg 2001, Branch et al 2002, Bustamante et al 2002, Okey et al 2004). Removal of top-predator fish species might explain the high abundance of urchins and other grazers on Galapagos reefs (Bustamante et al 2007).…”

Temporal changes in caiçara artisanal fishing and alternatives for management: a case study on the southeastern Brazilian coast

“…Even the use of simple techniques, such as hook and line, have reduced the fishing stocks in some places, thereby changing the structure of local fishing and invertebrate communities (de Boer et al 2001, Ruttenberg 2001. In response to such problems, some fishing communities have developed management strategies, including the self-regulation of extraction activities (Berkes 1985), restoring the legal acceptance of old management techniques (Levieil & Orlove 1990, McGrath et al 1993, McDaniel 1997.…”