title: Fishing degrades size structure of coral reef fish communities.
abstract: Fishing pressure on coral reef ecosystems has been frequently linked to reductions of large fishes and reef fish biomass. Associated impacts on overall community structure are, however, less clear. In size-structured aquatic ecosystems, fishing impacts are commonly quantified using size spectra, which describe the distribution of individual body sizes within a community. We examined the size spectra and biomass of coral reef fish communities at 38 US-affiliated Pacific islands that ranged in human presence from near pristine to human population centers. Size spectra 'steepened' steadily with increasing human population and proximity to market due to a reduction in the relative biomass of large fishes and an increase in the dominance of small fishes. Reef fish biomass was substantially lower on inhabited islands than uninhabited ones, even at inhabited islands with the lowest levels of human presence. We found that on populated islands size spectra exponents decreased (analogous to size spectra steepening) linearly with declining biomass, whereas on uninhabited islands there was no relationship. Size spectra were steeper in regions of low sea surface temperature but were insensitive to variation in other environmental and geomorphic covariates. In contrast, reef fish biomass was highly sensitive to oceanographic conditions, being influenced by both oceanic productivity and sea surface temperature. Our results suggest that community size structure may be a more robust indicator than fish biomass to increasing human presence and that size spectra are reliable indicators of exploitation impacts across regions of different fish community compositions, environmental drivers, and fisheries types. Size-based approaches that link directly to functional properties of fish communities, and are relatively insensitive to abiotic variation across biogeographic regions, offer great potential for developing our understanding of fishing impacts in coral reef ecosystems.
authors: Department of Biology, University of Victoria, PO BOX 1700 Station CSC, Victoria, BC, V8W 2Y2, Canada.
authors: James P W
authors: JP
authors: Robinson
authors: Pacific Islands Fisheries Science Center, Coral Reef Ecosystem Program, National Oceanic and Atmospheric Administration, 1845 Wasp Boulevard, Building 176, Honolulu, HI, USA.
authors: Ivor D
authors: ID
authors: Williams
authors: Department of Biology, University of Victoria, PO BOX 1700 Station CSC, Victoria, BC, V8W 2Y2, Canada.|Pacific Biological Station, Fisheries and Oceans Canada, 3190 Hammond Bay Road, Nanaimo, BC, V9T 6N7, Canada.
authors: Andrew M
authors: AM
authors: Edwards
authors: Centre for Conservation Research, Calgary Zoological Society, 1300 Zoo Road NE, Calgary, AB, T2E 7V6, Canada.|Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
authors: Jana
authors: J
authors: McPherson
authors: National Socio-Environmental Synthesis Center, 1 Park Place Suite 300, Annapolis, MD, 21401, USA.
authors: Lauren
authors: L
authors: Yeager
authors: Institut de Recherche pour le Développement (IRD), UMR ENTROPIE, Laboratoire d'Excellence LABEX CORAIL, BP A5, Noumea, New Caledonia, 98848, France.
authors: Laurent
authors: L
authors: Vigliola
authors: Pacific Islands Fisheries Science Center, Coral Reef Ecosystem Program, National Oceanic and Atmospheric Administration, 1845 Wasp Boulevard, Building 176, Honolulu, HI, USA.
authors: Russell E
authors: RE
authors: Brainard
authors: Department of Biology, University of Victoria, PO BOX 1700 Station CSC, Victoria, BC, V8W 2Y2, Canada.
authors: Julia K
authors: JK
authors: Baum
mesh_terms: D000818:Animals; D018533:Biomass; D003247:Conservation of Natural Resources; D057894:Coral Reefs; D005398:Fisheries; D005399:Fishes; D006801:Humans; D010139:Pacific Islands
keywords: body size; community structure; coral reef fish; exploitation; fisheries; macroecology; overfishing; size spectra; size-based approaches