Spotted Bass Population Structure and Diet in Wadeable and Non-wadeable Streams Draining the Lake Pontchartrain Basin

Spotted bass (Micropterus punctulatus) provide popular recreational fisheries in southeastern U.S. streams. We studied spotted bass population structure and diet from wadeable (< 1 m deep on average, n = 174, 21 sites) and non-wadeable (n = 498, 32 sites) reaches of the Lake Pontchartrain Basin in Mississippi and Louisiana to determine if populations should be managed separately by stream size. Sampling occurred April-November 2009-2012 by hook-and-line angling, boat-mounted electrofishing, and seines. Size structure was similar between stream type and with few quality-sized fish (PSD ≤ 24). Spotted bass relative weight (Wr) was higher in non-wadeable streams (mean Wr = 91) than in wadeable streams (mean Wr = 85). Larger spotted bass (> 200 mm TL) consumed more crayfish and fish, other vertebrates, and multiple types of aquatic and terrestrial insects by number. Crayfish and fish were eaten more frequently in wadeable streams than in non-wadeable streams. Maximum theoretical length (Linf) was greater for wadeable stream fish (Linf = 399 mm TL) than non-wadeable stream fish (Linf = 356 mm TL), but growth rates were similar between stream types. Sexual maturation rates for both sexes combined were similar with 50% of individuals maturing at 195 mm TL and 202 mm TL in non-wadeable and wadeable streams, respectively. Total annual mortality (A) estimated from weighted catch curves was 16% and 17% for non-wadeable and wadeable stream populations, respectively. Because population structure was similar, we recommend that spotted bass from wadeable and non-wadeable coastal plain streams be managed with consistent regulations.

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