Catch and Exploitation of Shoal Bass in the Flint River, Georgia, USA: Implications for Harvest Restrictions

Abstract

Shoal Bass Micropterus cataractae are endemic to the Apalachicola River basin (Alabama, Florida, and Georgia) and support popular fisheries, yet little is known about the population dynamics or angler harvest of this species. To estimate the annual exploitation rate (u), 376 Shoal Bass were tagged at 16 sites over a 208-km stretch of the Flint River, Georgia, during 2008–2011. Mean annual u varied from 0.22 to 0.26, but because of the high movement rates of tagged fish, it was not possible to calculate true u for specific sites along the Flint River. The catch rate of tagged, sedentary Shoal Bass was relatively similar between areas that were accessible by motorboat (0.38) and those accessible only by canoe or kayak (0.32); however, u was 2.5 times higher in the motorboat-accessible areas (0.22) than in motorboat-inaccessible areas (0.09). The effects of three length limits (the current minimum length limit [MLL] of 305 mm TL; an MLL of 381 mm TL; and a protected slot limit of 356–432 mm TL) on the Shoal Bass population were explored by using an age-structured model. Results indicated that growth overfishing did not occur with the current (305-mm) MLL under the observed range of u, but few fish (≤3%) reached 457 mm, indicating that the population’s size structure was likely limited by harvest. The 381-mm MLL was predicted to cause little decline in yield while (1) decreasing the number of harvested Shoal Bass by 41–42% and (2) increasing the number reaching 457 mm by 37–66%. Performance of the slot limit was similar to that of the 381-mm MLL in terms of yield and the number of fish reaching 457 mm, but the slot limit was predicted to increase the number of harvested fish by 15–17% relative to the 305-mm MLL and by almost two-fold relative to the 381-mm MLL. The Flint River Shoal Bass fishery is unlikely to achieve a trophy component under the 305-mm MLL at the observed levels of u. Based on the results of this study, the Georgia Department of Natural Resources adopted a 381-mm MLL for this reach of the Flint River on September 17, 2014.

Received May 27, 2015; accepted January 19, 2016 Published online May 26, 2016

Acknowledgements

I would like to especially recognize the assistance and support of Jimmy Evans and Wayne Clark (GADNR), who provided logistical help, sampling assistance, and the benefits of their long careers in sampling Shoal Bass on the Flint River. Numerous Auburn University personnel participated in this study over the years, including Jonathan Brown, Ryan Hunter, Aaron Kern, Ryan Lothrop, Mike Maceina, Matt Marshall, Chris McKee, and Tyler Thomas. Laurie Earley graciously provided her GIS expertise to complete the maps. This study was funded by GADNR under the Federal Aid in Sport Fish Restoration Act. Comments by two anonymous reviewers improved the manuscript.