Effects of hook size on the catches of undersized snapper Pagrus auratus

Demersal longlines baited with uniformly-sized pieces of squid were used to test the selective nature of 3 'Mustad' tuna hooks (#12, #10 and #8) on the catches of undersized legal-sized snapper Pagrus auratus. Increasing the absolute size of the hook by 26.5 % (i.e. #12 to #10) resulted in significantly fewer snapper under the legal size (250 mm fork length) being caught. Increasing the absolute size of the hook by 64 % (i.e. #12 to #8) did not result in a further decrease in the number of undersized snapper caught but, it did result in significantly larger individuals being caught on the #8 hook. Theses results indicate that predictions of hook-selectivity based on the normal and logistic curves are not directly applicable. An examination of other hook dimensions showed that the length of the bill was inversely correlated with the number of under legal-size snapper. These results suggest that other hook dimensions warrant further investigation.