Effect of hook eye alignment on deep hooking rates for stream-dwelling trout caught with baited circle and J hooks

It has been well documented that circle hooks generally reduce deep hooking of bait-caught fish. However, for decades there has been speculation that the hook eye must be straight relative to the shank for circle hooks to function properly, yet this aspect of hook configuration has rarely been investigated. Using a passive hook set when strikes were detected, we compared deep hooking rates and catch probability for stream-dwelling trout (Yellowstone cutthroat trout [Oncorhynchus clarkii bouvieri Jordan & Gilbert], rainbow trout [O. mykiss Walbaum], and cutthroat trout × rainbow trout hybrids) caught using baited circle and J hooks with the eye either straight with or turned-up from the shank. Landed fish averaged 26 cm in total length and ranged from 11 to 46 cm. Most fish (83%) were hooked either in the upper or lower jaw, but 16% were hooked deeply (i.e., either in the esophagus or the gills). As expected, the deep hooking rate was lower for circle hooks (10%) than for J hooks (24%). Logistic regression model results indicated that hook eye orientation had no effect on deep-hooking, with deep hooking rates of 11.0% and 8.2% for circle hooks with angled-up and straight eyes, respectively, compared to 21.7% and 25.3% for J hooks with angled-up and straight eyes. Model results also revealed that deep hooking probability differed among anglers but did not differ between species and was not related to fish length. Catch probability (i.e., the proportion of fish strikes that resulted in a landed fish) did not differ between hooks or hook eye orientations. Contrary to some perceptions, our results suggest that changing the angle of the hook eye does not affect deep hooking rates when anglers use baited circle hooks to land stream-dwelling trout.