Biology of a Spawning Population of Cycleptus meridionalis in the Alabama River

A spawning population of Cycleptus meridionalis was sampled 71 times in the generator outflow area below Millers Ferry Lock and Dam from 1995-2003. Sampling success ranged from 32 fish in 2001 to 247 fish in 2003. Sixty-seven percent of 1059 fish captured were males; 30% were females, and 3% were gender unknown. Females attained a greater total length and total weight than males. Regression slopes for standard length versus total length and total weight versus standard length were significantly different (P<0.01) between males and females. Collections of >100 fish indicated peak spawning activity occurred in late March when water temperatures ranged from 15 to 17 C. Most fish left the spawning area when water temperatures reached 20 to 21 C. Twenty percent of 702 Cycleptus meridionalis anchor tagged from 1995-2002 were recaptured from 1996-2003. Multiple recaptures confirm many Cycleptus meridionalis inhabiting the Alabama River spawn annually below the Millers Ferry Lock and Dam for at least nine years and possibly longer. Lower than expected Jolly and Jolly-Seber population estimates were probably influenced by the timing and number of samples collected annually, water level in the Millers Ferry tailwater and its effect on netting efficiency, the ability of the U.S. Army Corps of Engineers to discontinue hydroelectric discharge during the prime spawning season, and the effect of an extended drought on the ability of fish to move upstream past Claiborne Lock and Dam.

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