Fluctuating Asymmetry in Naturally Occurring
and Introduced Populations of Striped Bass

LORAINE T. FRIES AND D. JODY WILLIAMS (Texas Parks and Wildlife Department, A.E. Wood State Fish Hatchery, P. O. Box 947, San Marcos, Texas 78666)

BRUCE T. HYSMITH (Texas Parks and Wildlife Department, Route 4, Box 157, Denison, Texas 75020)

JAMES E. BULACK (South Carolina Wildlife Resources Department, 1324 Piney Branch Road, Eastover, South Carolina 29044)

Fluctuating asymmetry, the most commonly used measure of developmental instability, has been linked to reduced genetic variation. Genetic variation in striped bass Morone saxatilis from two introduced populations, the Trinity River, Texas (N=52) and the Red River on the Texas-Oklahoma border (N=61), and one naturally occurring population, the Santee-Cooper Reservoir, South Carolina (N=27) was examined using fluctuating asymmetry and protein electrophoresis. Fluctuating asymmetry was measured as the difference in counts between the left and right sides of individuals for the following features: pectoral and pelvic rays, scales above, along, and below the lateral line, and gill rakers on the first branchial arch. All characters except pelvic rays exhibited fluctuating asymmetry with the Trinity River population having the greatest mean magnitude of asymmetry (mean = 5.1), followed by the Red River (mean - 4.07), while the Santee-Cooper Reservoir had the least (mean = 2.80). Electrophoresis of polymorphic loci, GAPH*, IDHP*, EST-1*, PGM-1*, and PGM-3*, revealed no variation which is not uncharacteristic for the species. The high levels of fluctuating asymmetry reported among the introduced populations are cause for concern since reduced genetic variation can be associated with decreased performance. These results suggest a potential need for a management plan to increase genetic variation in the introduced populations.

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