Relative Abundance, Growth, and Mortality of Suwannee Bass in Four Florida Rivers

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AbstractIn an effort to aid in the conservation of black basses, the relative abundance, growth, and mortality of Suwannee bass Micropterus notius and largemouth bass M. salmoides were estimated from four Florida rivers. Fish were collected by electrofishing in the four rivers during 2001 and 2002. Electrofishing catch per unit effort of Suwannee bass was highest in the Wacissa River (95.1 fish/h), intermediate in the Santa Fe River (22.6 fish/h), and lowest in the Withlacoochee (5 fish/h) and Ochlockonee rivers (1.9 fish/h). Catch per unit effort for largemouth bass was also highest in the Wacissa River (50 fish/h), intermediate in the Santa Fe (19.8 fish/h) and Ochlockonee rivers (17.1 fish/h), and lowest in the Withlacoochee River (9.9 fish/h). Mean total length (TL) at age across the four Suwannee bass populations was described by von Bertalanffy growth curves as TL = 386.1 · (1 − e−0.3733(age+0.7772)) for females and as TL = 324.1 · (1 − e−0.4735(age+0.6543)) for males. Mean TL at age across the three largemouth bass populations was also described by von Bertalanffy growth curves as TL = 644.2 · (1 − e−0.2064(age+0.9840)) for females and TL = 427.8 · (1 − e−0.3164(age+0.9991)) for males. Suwannee bass exhibited sex‐specific growth rates similar to those of largemouth bass, females experiencing more rapid growth and attaining larger sizes than males (F1, 564 = 20.39; P < 0.01). Suwannee bass total annual mortality (A) averaged 40%, ranging from 28% to 46%. Similarly, largemouth bass total A averaged 40%, ranging from 35% to 46%. The current Florida minimum length limit on Suwannee bass directs fishing mortality almost solely to females, but estimates of fishing mortality are needed to determine whether this is a concern for black bass with a small native range.