Life History Aspects of the Black Madtom, Noturus funebris (Siluriformes: Ictaluridae), in the Cahaba River Drainage, Central Alabama, USA

Abstract

ABSTRACT The black madtom (Noturus funebris) is a diminutive catfish (maximum standard length 124 mm) found throughout the southeastern United States. Life history aspects of N. funebris were examined using 298 specimens from Blue Girth Creek, a sand-bottomed second-order tributary to the Cahaba River in Bibb County, Alabama, collected in 1987–1988. Noturus funebris was associated with undercut banks, root masses, and woody debris. The youngest reproductive female was 3 years old. Noturus funebris produces many eggs (mean = 109 ova per female) compared to other species within the subgenus Schilbeodes; however, relative fecundity (oocytes per g body weight) indicated a lower relative position in the subgenus. Analysis of gonads and presence of young-of-the-year indicated a spawning season from late June to August. One nest of N. funebris was collected in July 1988 in a glass bottle with 70 eggs. Sex ratio was nearly 1:1. In summer 2005, placement of 30 clay flowerpots as in-stream artificial nesting cavities yielded no additional nests, which suggested a preference for smaller, closed cavities. Analysis of stomach contents indicated a similar diet to other Noturus species, which consisted mainly of decapods and larvae of dipterans, mayflies, and caddisflies. Odonates made up the higher percent of diet volume in winter, crayfish in the spring, and plant material in the summer. Length-frequency data indicated four size (age) classes, with most individuals in the age 0+ and other classes containing similar proportions of individuals. A potential age-4 class consisted of three individuals greater than 108 mm SL.