Stocking of Advanced-Fingerling Largemouth Bass to Supplement Year-Classes in Lake Talquin, Florida

摘要

Supplemental stocking of largemouth bass Micropterus salmoides has often resulted in limited success in large systems. We evaluated the contribution and relative abundance of advanced-size (65-90 mm total length [TL]) hatchery Florida largemouth bass M. salmoides floridanus that were stocked into Lake Talquin (3,561 ha) to supplement year-classes. Stocking density varied from 15 to 60 fish/ha from 2000 to 2003. Coded wire tags and unique nuclei in the sagittal otoliths of hatchery fish were used to identify stocked fish to estimate percent contribution and relative abundance. Hatchery fish released by May 15 used threadfin shad Dorosoma petenense as a primary food source at significantly higher (P < 0.05) frequencies than did wild age-0 Florida largemouth bass examined from June to October. Dominant modal size-groups (20-27 cm TL) of age-0 hatchery fish in October electrofishing were larger than those of age-0 wild fish (10-14 cm TL). Hatchery fish made up an estimated 17-40% of the age-0 fish collected during October electrofishing from 2000 to 2003. The highest stocking density (60 fish/ha) resulted in a 40% hatchery contribution to electrofishing samples at age 0 and a 37% contribution to electrofishing samples at age 3. For the group stocked at the highest density, electrofishing catch per unit effort (CPUE) at age 0 (26 fish/h) and age 3 (8 fish/h) was higher (P < 0.05) than that for groups stocked at lower densities (15-39 fish/ha; age-0 CPUE = 7-17 fish/h; age-3 CPUE = 2 fish/h). Hatchery fish contribution to largemouth bass angler tournament catch in April-May 2004-2006 was estimated to be at least 20% after 4 years of variable stocking. Several factors, such as appropriate time of stocking, size at stocking, food supply, and age-0 wild and stocked fish densities, influenced hatchery fish contributions to each year-class and the fishery.