Dispersal of Tournament-Displaced Largemouth Bass and Spotted Bass in Lake Martin, Alabama

Abstract

Anglers fishing in tournaments for black basses Micropterus spp. often displace fish great distances from the site of capture. Accumulation of black bass, which may have negative effects on populations and the fishery, can occur when many tournaments displace large numbers of fish to a single tournament processing site. Thirty-nine largemouth bass Micropterus salmoides and spotted bass M. punctulatus were implanted with radio transmitters in spring 2005 and tracked for nearly 1 year. Twenty of these fish were transported to a popular tournament release site on Lake Martin (16,188 ha), Alabama, to observe the effect of simulated tournament displacement on movement and dispersal. The other fish were released after radio tag implantation at their capture site and served as control fish. In addition, 7 fish/species were collected from tournaments and implanted with transmitters in fall 2005 and tracked for 4.5 months to monitor postrelease behavior. In spring, displaced fish moved more than control fish after 3–4 weeks and dispersed from the release site over time. Movement and behavior of displaced fish was altered for up to 6 months after release compared with control fish. After 10 weeks, displaced fish moved an average of 7.4 km and control fish moved an average of 1.3 km; during the first 6 months, daily movement was about two to five times greater for displaced fish. Tournament-displaced fish tagged in fall 2005 moved less than the fish subjected to simulated displacement in spring 2005, and less movement in fall coincided with cooler and falling water temperatures. Some fish remained within 2 km of the release site for up to 3 months. In fall 2004 and spring 2005, anglers released at least 6,600 black bass at the site. We estimated that black bass biomass increased by 6–9 kg/ha within 2 km of the release site, translating to a probable 50–100% increase in resident black bass biomass. Fisheries managers should encourage or require the use of release boats, transport trailers equipped with live wells, and multiple release sites on reservoirs where tournament-related accumulation is suspected.