Spawning performance in North American minnows: direct evidence of the occurrence of multiple clutches in the genus Notropis

Abstract

Pairs of laboratory–reared F1, and F2 males and females of Notropis leedsi were observed in aquaria. Analyses of spawning histories and ovum diameter histograms showing the pattern of ovum development demonstrated that females produced multiple clutches of eggs. Each clutch is comprised of oocytes which undergo synchronous development and are oviposited within a relatively short period of time. Examinations of collections from streams in Florida and Georgia showed that N. leedsi has a spawning season which lasts at least from May to September. Because the pattern of ovum development in wild‐caught females was the same as that observed in laboratory females, we believe that our laboratory observations demonstrate processes which occur in the natural environment. A total of 193 spawning intervals was observed in 34 pairs kept at 22–26°C in the laboratory. The interspawning intervals ranged from 3 to 10 days, with a mean of 4.6 days and a mode of 4 days. The clutches ranged in size from 26 to 28 ova for females of 36.7–52.5 mm standard length.