TN00020 FRESHWATER DRUM APLODINOTUS GRUNNIENS
Physical description: This is a compressed and high-backed, spiny-rayed fish of medium to large size, with the adults usually from 250-650 mm TL. The head is short, strongly declined to the snout; the snout is blunt; the mouth moderate, subterminal; frenum absent; upper lip with small central pore flanked by two slits; pharyngeal teeth are well developed, in sizable patches, malariform; chin with 5 pits medially; branchiostegal membranes free from isthmus. The two dorsal fins are partly connected, first dorsal arched with stout spines, second long; caudal rounded to triangular distally; pelvic with distal filament. Scales ctenoid, caudal fin partly scaled. The male has a single urogenital opening behind the anus; the female has seperate genital and urinary orifices. Lateral line scales 49-53, all pored, and additional pored scales continuing to the end of the caudal fin. Dorsal spines 8-9; second dorsal with 1 leading spine, rays 25-33; anal spines 2, second spine very strong; anal rays 7-8; pectoral rays usually 17. The back is gray, dark green or olive-brown; the body overall is silver with subtle blue and purple reflections; pelvic often orange-tinged *4205*. Reproduction: Spawning typically occurs from early May through July, depending on the latitude, and may extend into September. Water of 18.9-22.2 degrees C brings on spawning. The eggs are ca 1 mm in diameter and they and the early larvae float in the surface film *4205*. Behavior: The freshwater drum is predominantly a benthic feeder. The young and small juveniles consume mostly microcrustaceans and midge larvae. With further growth, larger immature aquatic insects become important food items. Mayfly larvae and small crustaceans are significant dietary components through the majority of life. Adults complement the diet with crayfishes and small fishes. With the onset of the spawning season, males begin to produce a drumming sound, likely an attractant to females. Drum spawn plagically by scholing in open water, often a good distance from shore *4205*. Population parameters: Males mature from 3-6 years of age, and females are mature at 7 years. The maximum recorded age is 17 years. Fecundity ranges from 27,000 to 508,000 eggs *4205*.
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4205
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