Growth History of Black Crappie Spawned 1980, St. Johns River, Florida

Growth rates for the 1980 year class of black crappie were determined from samples collected in the St. Johns River, Florida, 1981 through 1987. Actual mean lengths of groups of black crappie aged by otolith evaluation were compared to back calculated lengths from otoliths of black crappie collected each year. Differences in actual and back calculated lengths for black crappie collected were not significant (P > 0.05). Coefficient of determination values (r2) dropped rapidly as differential growth rates increased. Overall, back calculated lengths for age I and II black crappie increased as fish aged, exhibiting a reverse of Rosa Lee's phenomenon. The phenomenon was probably the result of size selective mortality. Black crappie collected between 1981 and 1986 indicated that the 1980 year class was larger than any other year class sampled. At actual age 6, the 1980 year class still comprised almost 8% of all black crappie collected.

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ID
28744