Improving Vulnerability to Angling of Rainbow Trout: A Selective Breeding Experiment
Joseph R. Kozfkay, Daniel J. Schill, and David M. Teuscher
Abstract.—A primary goal of put-and-take hatchery trout programs is to maximize the return to creel of stocked fish, thereby improving cost efficiency. Return to creel rates and number of days to harvest for two groups of catchable-sized rainbow trout Oncorhynchus mykiss were compared. The groups were produced from (1) normal Hayspur-strain broodstock, and (2) Hayspur-strain broodstock that exhibited high levels of vulnerability to angling. Ninety-four 1-h fishing trials were conducted, and capture frequency for each fish was recorded. Fish caught three or more times were retained as vulnerable broodstock. The normal broodstock was formed with other, randomly selected, Hayspur-strain brood fish that had not been subjected to fishing trials. Equal numbers of progeny from normal and vulnerable broodstocks were tagged and stocked into 16 water bodies during 2001 and an additional 16 water bodies during 2002. A total of 798 tags were returned out of 6,389 stocked during 2001. Mean first-year return rate for the vulnerable group (12.7 ± 3.5%) was not statistically different from the normal group (11.7 ± 3.8%; paired t-test, p = 0.30, df = 15). The mean time to harvest was 46.4 ± 9.8 d for the vulnerable group and 50.6 ± 10.7 d for the normal group. This disparity was not statistically different (paired t-test, p = 0.77, df = 15). For fish stocked during 2002, 700 tags were returned out of 9,593 stocked. Mean firstyear return rate for the vulnerable group (7.2 ± 2.5%) was not different from the normal group (7.4 ± 2.7%; paired t-test, p = 0.80, df = 15). There was no difference in mean time to harvest for the normal group (36.0 ± 8.0 d) and vulnerable group (38.7 ± 7.3 d; paired t-test, p = 0.45, df = 15). No performance benefit in terms of increasing return to creel or reducing time to harvest was achieved through selective breeding.