Comparison of Growth, Abundance, and Emigration of Two Morone Hybrids in a High Flow-through Oklahoma Reservoir

Hybrid striped bass (Morone saxatilis x Morone chrysops) are commonly introduced in southeastern U.S. reservoirs to create a sport fishery and as a means of utilizing abundant shad (Dorosoma spp.) populations. The Oklahoma Department of Wildlife Conservation (ODWC) has historically stocked the common-cross hybrid (M. saxatilis female x M. chrysops male; hereafter, common HSB) rather than the reciprocal-cross hybrid (M. saxatilis male x M. chrysops female; hereafter, reciprocal HSB). Due to concerns over downstream emigration of stocked fish from reservoirs, common HSB have mostly been stocked in reservoirs with low water exchange rates; whereas stockings in high flow-through reservoirs have been limited. Some evidence exists that reciprocal HSB have less tendency to emigrate from the reservoirs they are stocked in; however, a direct comparison of the two Morone hybrid crosses in Oklahoma reservoirs had never been done. Therefore, the objective of this study was to compare growth, abundance, and emigration of common HSB and reciprocal HSB in a high flow-through reservoir. Kaw Lake was stocked annually with equal numbers (85,000) of each hybrid cross from 2005 - 2008; lesser, but approximately equal, numbers of each hybrid cross were stocked in 2009. Relative abundance of both hybrid crosses was similar in Kaw Lake and in the basin below Kaw Lake over the course of this study. Thus, emigration of both hybrid crosses appeared to be similar. However, growth of common HSB was greater than that of reciprocal HSB. Based upon the results of this study, ODWC modified its hybrid striped bass stocking protocol to allow for more stocking of common HSB into reservoirs with high water-exchange rates.

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