SIZE-STRUCTURAL SHIFTS REVEAL INTENSITY OF EXPLOITATION IN CORAL REEF FISHERIES
Fisheries represent a considerable threat to coral reef resources because fishers typically target large-bodied species. Although species occupying higher trophic groups are known to suffer a majority of the exploitative effects, changes in composition among lower trophic groups may be significant. Using size-based biomass spectra analysis, we investigate the effects of fishing on the size-structure of fish assemblages and determine if patterns of exploitation vary across trophic groups. Our analyses reveal striking evidence for the effects exploitation can have on fish assemblages. When examining biomass spectra across the entire assemblage we found consistent evidence of “size-specific exploitation”, a process by which large-bodied individuals experience disproportionate reductions within the top predatory trophic group. However, when assemblages were analyzed among trophic groups, two additional forms of exploitation were realized; “size-biased exploitation”, in which all sizes are exploited with a bias toward greater proportional effect on larger-bodied individuals, and “size-neutral exploitation”, in which proportional exploitation is equivalent across all size classes. Importantly, the breadth of size classes and trophic groups that showed evidence of exploitation related positively to local human population density and diversity of fishing methods employed. Our findings highlight the complexity of coral reef fisheries and that the effects of exploitation are realized across multiple trophic groups and not solely restricted to large-bodied top-predators.
Zgliczynski, B. J., Scripps Institution of Oceanography, UC San Diego, USA, email@example.com
Sandin, S. A., Scripps Institution of Oceanography, UC San Diego, USA, firstname.lastname@example.org
Location: 310 THEATER
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