Effects of artisanal fishing on marine communities in the Galapagos Islands

The Galapagos 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.