Spatial and fishing effects on sampling gear biases in a tropical reef line fishery

Welch, David J., Mapstone, Bruce D., Davies, Campbell C., and Russ, Garry R. (2010) Spatial and fishing effects on sampling gear biases in a tropical reef line fishery. Marine and Freshwater Research, 61 (10). pp. 1134-1146.

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Biased estimates of population parameters for harvested stocks can have severe implications for fishery management strategy choices. Hook-and-line fishing gear is size-selective and therefore collects biased samples from wild populations. Such biases may also vary in space and time. To assess this assertion, we compared line- and spear-caught samples of the main target species of an Australian hook-and-line fishery to quantify relative bias in size and age structure estimates. We also assessed the consistency of biases among four fishery regions and between two management zones – areas open and closed to fishing. Fish less than 310 mm and younger than 4 years comprised a larger proportion of the speared than the line samples regardless of region or management zone. Conversely, hook-and-line sampled more fish in larger size classes (>370 mm) and older age classes (≥6 years) relative to spear fishing. These biases were qualitatively, but not quantitatively, consistent in all regions and management zones. This variation in sampling resulted in different inferences about regional and zone-related patterns in population size and age structure. We recommend careful consideration of sampling bias when drawing conclusions about regional and management zone effects on fish populations.

Item ID: 15235
Item Type: Article (Research - C1)
ISSN: 1448-6059
Keywords: bias, coral trout, Great Barrier Reef, hook-and-line, no-take zones, selectivity, spearfishing
Date Deposited: 21 Jan 2011 04:11
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070402 Aquatic Ecosystem Studies and Stock Assessment @ 100%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8302 Fisheries - Wild Caught > 830204 Wild Caught Fin Fish (excl. Tuna) @ 100%
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