Reproductive Potential of the Black Bullhead, Ictalurus melas, in Clear Lake, Iowa

Abstract

Gonadal development, time of spawning, and fecundity of black bullheads were examined in 1969 and 1970 for insight into the reproductive potential of this species in a warm-water lake. Maturity indexes peaked around 1 June in both years. Spawning was evidently triggered by rising water temperatures during June. Fecundity seemed unrelated to body length because ovaries of fish of similar length varied more than 100% in number of mature ova present. INTRODUCTION The black bullhead, Ictalurus melas, is an extremely abundant species in Clear Lake, a shallo.w, eutrophic lake in western Cerro Gordo County, Iowa. Bullheads compete for food with many other fishes present (Ridenhour, 1960; Welker, 1963) and probably considerably deplete food otherwise available to more desirable species (Baur, 1970). Bullheads also are forage fish for piscivorous species, such as the walleye (Jernejcic, 1969). Thus, variations in bullhead reproductive potential can provide valuable insight into the ability of this species to maintain itself in the lake. This study was initiated in May 1969 to obtain knowledge concerning the normal reproductive cycle of the black bullhead and variations in fecundity that might be related to water temperature, to body len•h and to body weight. MATERIAL AND METHODS Black bullheads larger than young-of-theyear were collected at various sites in Clear Lake by gillnet or electrofishing from 15 May to 29 September 1969, and from 19 May to 23 June 1970. Most fish were frozen soon after capture. Total length of thawed fish was measured to the nearest millimeter. The abdomen and stomach were opened, and the stomach Conservation Commission, cooperating. ß o ß ß o ß o o oo ß ooo ß ß ß ß ß 180 230 280 TOTAL LENGTH (ram) Flctmz &--Relationship of egg number to total body length for Clear Lake black bullheads captured

Population Biology of the Brown Bullhead (Ictalurus nebulosusLesueur)

“…We found the fecundities to be similar, however, to those of black bullheads (Ictalurus melas Rafinesque) (Dennison and Bulkley 1972). The bullhead eggs had a mean diameter of 2.17 mm and a mean weight of 0.005 g. No relationship was found between fecundity and length or weight, which also corresponds with findings for black bullheads (Dennison and Bulkley 1972).…”

Boom‐bust like dynamics of invasive black bullhead (Ameiurus melas) in Lake Sava (Serbia)

“…Mean relative fecundity for European black bullhead ranges from 25.1 in Slovakia (Tisa oxbows) to 221.4 in England (Tom's Pond), with an overall mean of 99.6 (Copp et al., ). These values are significantly higher than those for native populations, which range from 5.5 (Dennison & Bulkley, ) to 18.8 (Maddux, ). Based on these results, Copp et al.…”

“…In addition to early maturation, fecundity also increased in the Lake Sava population following the mass mortality event, with absolute fecundity ranging from 1,702 to 4,447 (mean 2,896) in 2011, and 16,88 to 12,073 (mean 3,927) in 2012. In comparison, absolute fecundity of specimens from the River Váh (Slovakia) ranged from 1,238 to 4,755 (mean 2,610) (Novomeská & Kováč, ), while those for North American populations ranged from 2,047 to 5,495 in Iowa (Dennison & Bulkley, ), 2,552 to 3,372 in Kentucky (Campbell & Branson, ), and 2,550 to 3,850 in Virginia (Jenkins & Burkhead, ). A review of growth and life‐history traits in European black bullhead populations (Copp et al., ) indicated that absolute fecundity ranges from 1,251 to 7,975 (mean 4,446), being slightly (but not significantly) higher than that for native populations (2,155‐6,820, mean 3,609).…”

Reproductive ecology and diet of a persistent Ameiurus melas (Rafinesque, 1820) population in the UK

“…It was also coincident with a relatively high mean air temp of 18.3°C (Central England Temperature; Meteorological Office, ). In its native range, A. melas spawning tends to occur at temperatures of 21°C (Dennison and Bulkley, ), whilst in their invasive range, Novomeská and Kováč () suggested spawning in Slovakian oxbow lakes occurs at 18 to 22°C. Thus, temperature was not an inhibitor of A. melas reproductive success during our study period and so is unlikely to explain their inability to be invasive in the UK more generally.…”