Comparison of Mortality and Diet Composition of Pellet-Reared Advanced-Fingerling and Early-Cohort Age-0 Wild Largemouth Bass through 90 Days Poststocking at Lake Seminole, Florida

Abstract

Advanced-fingerling Florida largemouth bass Micropterus salmoides floridanus (N = 18,263; mean total length = 77 mm) reared on pellet feed specifically formulated for largemouth bass were tagged with coded wire tags and stocked on 28 May 2008 in a 162-ha lobe of hypereutrophic Lake Seminole (283 ha) in Pinellas County, Florida. We compared mortality and diet composition of stocked advanced-fingerling and early-cohort wild age-0 largemouth bass through 90 d poststocking. Our mortality estimates were similar for stocked (84%) and early-cohort age-0 wild largemouth bass (95%) based on the slope of a catch curve. We used a percent similarity index (PSI) to evaluate the diet composition of stocked and early-cohort wild age-0 largemouth bass. Diet composition was generally similar between stocked and wild fish, although the greatest dissimilarity occurred at 7 d poststocking (PSI = 0.48). Pearson chi-square analysis indicated that early-cohort age-0 wild largemouth bass had a significantly higher frequency of diets containing fish than stocked largemouth bass and that stocked fish had a significantly higher frequency of empty stomachs at 7 d poststocking. An inability to transition to natural prey, stresses from the stocking process, and/or other factors not measured in this study (e.g., predation) probably contributed to the mortality of stocked fish through 90 d poststocking. We recommend that hatchery managers and biologists conduct further research on the hatchery fish rearing protocol (e.g., transition to natural prey and habitat complexity in raceways) that may lead to increased survival of stocked advanced-fingerling largemouth bass.