The Natural Reproductive Cycle of Northern Largemouth Bass Micropterus salmoides salmoides in the Upper Midwest, with Applications to Out-of-season Production

Daniel E. Spengler

Largemouth bass Micropterus salmoides are one of the most sought-after freshwater game fishes in the United States (USDOI 2007).  Due to their popularity and importance as a top-level predator, they have been broadly distributed beyond their native range.  In South Dakota, largemouth bass provide angling opportunities and play a fundamental role in regulating panfish in small impoundment communities.  However, harsh environmental conditions (e.g., severe winters) often limit the establishment of successful largemouth bass populations; therefore, periodic augmentation of these populations is necessary.  To supplement these populations, northern largemouth bass M. s. salmoides fingerlings are produced at Blue Dog State Hatchery using traditional pond culture methods (Broughton et al. 2006).  Fingerlings (~75 mm) are harvested and transported to stocking sites during late summer.  However, survival to age-1 is negligible in established fish communities, likely due to a combination of size (e.g., predation vulnerability) and condition (lack energy stores required to overwinter).  These issues justify the need to develop hatchery procedures directed at producing advanced sizes of largemouth bass.  Alternatives, such as out-of-season production of largemouth bass, may be used to produce larger, age-0 stocking products in the upper Midwest.  To successfully produce fishes outside of their natural spawning period it is necessary to investigate key physical cues, such as photoperiod and temperature, in combination with physiological parameters that function in reproductive processes.  Thus, 10 largemouth bass (five male, five female) will be collected each month from a private impoundment near Brookings, SD for one complete reproductive cycle.  Seasonal variation among sex steroid hormones, vitellogenin, organosomatic indices (e.g., gonadosomatic index), and gonadal histologies will be documented (Gross et al. 2002).  Photoperiod and temperature will be monitored in situ using data loggers during the cycle.  Sex steroid hormones and vitellogenin concentrations will be assessed using radio-immunoassays and enzyme-linked immunosorbent assays, respectively.  Analysis of organosomatic indices, sex steroid hormones, and vitellogenin across months will be evaluated with one-way analysis of variance (α = 0.05), followed by a Tukey’s Multiple Comparison test.  In addition to the reproductive cycle assessment, 65 age-1 largemouth bass will be domesticated in a recirculating system at South Dakota State University.  These fish will serve as broodstock for out-of-season production trials (e.g., cycle compression or shift).  Successful out-of-season production of largemouth bass would provide advanced sized bass for earlier stocking dates.  Stockings occurring earlier in the growing season would provide a window for age-0 fish to attain greater lengths and accumulate more energy reserves prior to winter, potentially enhancing survival.  

References:

Broughton, J., R. Smidt, C. Soupir, E. Holm, S. Kennedy, and R. Whitlock. 2006. 2006 annual production report, Blue Dog Lake State Fish Hatchery. Annual Report No. 07-22, South Dakota Department of Game, Fish and Parks, Pierre.

Gross, T. A., C. M. Wieser, M. A. Sepulveda, J. J. Wiebe, T. R. Schoeb, and N. D. Denslow. 2002. Characterization of annual reproductive cycles for pond-reared Florida largemouth bass Micropterus salmoides floridanus. American Fisheries Society Symposium 31: 205-212.

USDOI (U.S. Department of the Interior, Fish and Wildlife Service and U.S. Department of Commerce, U.S. Census Bureau). 2007. 2006 National Survey of Fishing, Hunting, and Wildlife-associated Recreation. U.S. Department of the Interior, Washington, D.C.