Evaluation and Management of Hybrid Striped Bass in Monroe Lake, Indiana
Kevin J. Hoffman, Dave S. Kittaka, and Brian M. Schoenung
Abstract.—Striped bass Morone saxatilis movements and population dynamics have been well studied in midwestern impoundments; however, a paucity of information exists on hybrid striped bass in these systems. We studied palmetto bass (male white bass M. chrysops × female striped bass) population dynamics and seasonal movements from 2005 to 2007 at Monroe Lake, a 4,350-ha flood control impoundment in south-central Indiana. Palmetto bass were collected, measured, and aged using otoliths to assess growth and mortality. Thirty fish were tagged with radio tags in April 2006 to determine seasonal movements and distributions for 1 year. Oxygen and temperature profiles were measured throughout the year to determine available habitat. Total annual mortality was 32% (±5%). Catch-curve residuals were modeled against the number of fish stocked to investigate recruitment variability. More than 95% of the variation in year-class strength was explained by the number of age-0 fish (25–50 mm total length) stocked in early summer. We determined that optimal stocking rates were between 12 and 23 fish/ha. Fish moved more during spring (501 m/d) than other seasons (109–220 m/d). Fish were concentrated in the lower basin of the lake during summer and in the upper basin during winter. Based on minimum habitat suitability index values for temperature and dissolved oxygen, there was no optimal habitat available in winter or spring. The volume of optimal habitat increased to 22% of the lake during summer and 47% in fall. Based on our evaluation of population dynamics, seasonal movements, available habitat, and stocking efficiency, current management strategies of hybrid striped bass in Monroe Lake are adequate to sustain a healthy fishery at similar levels of mortality.