Dynamics of Hybrid Sunfish in Southern Illinois Farm Ponds

Control of population density in southern Illinois farm ponds was achieved by stocking F, hybrid sunfish of the male bluegill (Lepomis macrochirus) X female green sunfish (L. cyanellus) and the male redear sunfish (L. microlophus) X female green sunfish with largemouth bass (Micropterus salmoides). Four of 30 ponds sampled were contaminated by nondesirable species from the watershed. Little or no recruitment of the F, generation occurred in ponds containing largemouth bass. In those populations where the hybrids were supplementally fed and bass were present, the F, bluegillX green sunfish hybrid averaged 159 g at annulus 3, and 199 g at annulus 4. In nonfed populations with bass this hybrid averaged 148 g at annulus 4. The F, redear sunfish X green sunfish hybrid averaged 127g at annulus 4 in nonfed populations with bass. Multiple regression analysis revealed that the presence of largemouth bass and supplemental feeding had a high positive correlation (0.001 probability level) to growth of both F, hybrids. Pond owners considered the hybrid sunfish to be much more vulnerable to angling than the channel catfish (lctalurus punctatus). Owners who stocked largemouth bass into their ponds were satisfied and would stock hybrid sunfish into another pond, although a majority of the owners without bass in their ponds were disappointed and would not stock hybrid sunfish into another pond.

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