Regional variation in the benefit of no-take marine reserves on reproductive output of the common coral trout, Plectropomus leopardus
Conference Contribution ResearchOnline@JCUAbstract
No-take marine reserves potentially protect against overfishing by allowing larger, older, and more fecund fish to prosper. However, few studies have empirically tested the effect of no-take marine reserves on reproductive output, particularly for hermaphroditic species. We estimated batch fecundity from hydrated ovaries of the major target species in the Great Barrier Reef (GBR) coral reef finfish fishery, the common coral trout Plectropomus leopardus. Coral trout were collected from reefs zoned open and closed to fishing in the moderately fished central (Townsville, ~18.5S) and lightly fished northern (Lizard Island, ~14.5°S) regions of the GBR over four spawning seasons (1998 – 2001). There were significant but weak positive relationships between batch fecundity and female fork length (r2=0.226, p<0.001, n=415), somatic weight (r2=0.187, p<0.001, n=403) and age (r2=0.086, p<0.001, n=400). Townsville's protected reefs were the only reefs where the fecundity-length relationship was significantly and consistently positive each year. This pattern was driven by larger spawners producing significantly more eggs per batch, and the high number of females in spawning condition caught on Townsville's protected reefs compared to fished reefs and Lizard Island's fished and protected reefs. Although protecting larger P. leopardus from fishing will increase reproductive output, this study highlights the need to consider regional variation in reproductive output of exploited species when designing marine protected areas. The large amount of variation in the length-fecundity relationship may also be confounded by sex change in protogynous hermaphrodites like P. leopardus, indicating marine reserves may not benefit all reproductive strategies equally.
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ANNIMS 2009: Australian National Network in Marine Science Inaugural Conference
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1
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Hobart, TAS, Australia
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Australian National Network in Marine Science
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Hobart, TAS, Australia
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