Population Biology Of Madtoms; A Review And Generalized Model

Matthew D. Chan and Timothy Copeland
101 Cheatham Hall (0321), Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA 24061. Tel. 540-231-3329 Fac. 540-231-7580 E-mail: (MDC) machan@vt.edu (TC) tcopelan@vt.edu

Madtoms (genus Noturus) are a cryptic group of dwarf catfishes, consequently they are overlooked by fisheries managers. Madtoms are often locally important bait fish and most species are threatened or endangered in parts of their distribution. We constructed a Leslie matrix model of a generalized madtom population from the literature and compared madtom life history information against the assumptions of age-structured models. Even for well studied species, critical management information was lacking for such models. Madtom populations meet model assumptions of closed populations. Species have initial sex ratios of 1:1 but females do not live as long as males (by 1 or 2 yrs). Most species mature at Age 2 and number of eggs per nest is unrelated to size of guardian males. Currently, no information exists on genetic structure of populations and there is little knowledge of temporal and spatial variation of parameters for species. Results from the model indicate that potential female reproductive capacity exceeds available environmental resources based on literature reports of age class survival and population densities. Our results are useful to managers interested in conservation or restoration of madtoms by suggesting controlling factors of madtom populations.