Initial Predation of Stocked Fingerling Largemouth Bass in a Texas Reservoir and Implications for Improving Stocking Efficiency

Abstract

We assessed the importance of initial predation as a source of mortality of stocked fingerling Florida largemouth bass Micropterus salmoides floridanus (30–46 mm total length). Florida largemouth bass were tagged with coded wire tags and stocked (3,000 fish/site) at six sites in Elm Creek Embayment of O. H. Ivie Reservoir, Texas—the location of an earlier study in which the immediate mortality of stocked fish was found to be highly variable. Stocked fish were eaten by at least five species of predators that varied widely in size. Ninety-three percent of the stocked fish recovered from predator stomachs were consumed by juvenile and adult largemouth bass M. salmoides and smallmouth bass M. dolomieu. Assuming a capture efficiency of 8% for our predator sampling, losses of stocked fish to predation were as high as 27.5% within 12 h of stocking, and losses generally increased with predator density. In comparison, the mortality of stocked fish held in predator-free enclosures was only 3.5% at 84 h poststocking, indicating that mortality resulting from transport and other variables was low and similar among stocking sites (P = 0.17). This study suggests that predation was the primary factor affecting the poststocking survival of fingerling Florida largemouth bass, and we recommend that managers consider predator densities when selecting stocking sites. Future efforts should examine the relationships between predation and habitat variables such as habitat composition and habitat complexity. Additional research should evaluate alternative stocking strategies such as using larger fish and habituating stocked fish before release.