Assessing the importance of fishing impacts on Hawaiian coral reef fish assemblages along regional-scale human population gradients

• Published in: Environmental conservation 2008-09, Vol.35 (3), p.261-272
• Main Authors: WILLIAMS, I. D., WALSH, W. J., SCHROEDER, R. E., FRIEDLANDER, A. M., RICHARDS, B. L., STAMOULIS, K. A.
• Format: Article
• Language: English
• Subjects: Animal populations; Animal, plant and microbial ecology; Anthropogenic factors; Apex predators; Applied ecology; Biological and medical sciences; Biomass; Conservation, protection and management of environment and wildlife; Construction; coral reef; Coral reefs; Environmental degradation; Environmental impact; Environmental protection; Environmental quality; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fish; Fish populations; Fishers; Fishing; Fundamental and applied biological sciences. Psychology; habitat; Habitat degradation; Habitats; Hawaii; Human; Human population density; Human populations; introduced species; Local population; Marine fishes; natural refugia; Ocean fisheries; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Population density; Predators; Refugia; Shorelines
• ISSN: 0376-8929; 1469-4387
• DOI: 10.1017/S0376892908004876

Humans can impact coral reef fishes directly by fishing, or indirectly through anthropogenic degradation of habitat. Uncertainty about the relative importance of those can make it difficult to develop and build consensus for appropriate remedial management. Relationships between fish assemblages and human population density were assessed using data from 18 locations widely spread throughout the Main Hawaiian Islands (MHI) to evaluate the significance of fishing as a factor potentially driving fish trends on a regional scale. Fish biomass in several groups was negatively correlated with local human population density and a number of lines of evidence indicate that fishing was the prime driver of those trends. First, declines were consistently evident among fish groups targeted by fishers, but not among lightly fished or non-target groupings, which indicates that declines in target groups were not simply indicative of a general decline in habitat quality along human population gradients. Second, proximity to high human populations was not associated with low fish biomass where shoreline structure prevented ready access by fishers. Relatively remote and inaccessible locations within the MHI had 2.1–4.2 times the biomass of target fishes compared to accessible and populous locations, and may therefore function as partial refugia. However, stocks in those areas were clearly far from pristine, as biomass of large predators was more than an order of magnitude lower than at more intact ecosystems elsewhere in the Pacific.