Spottail Darter (Etheostoma squamiceps) Spawning Ecology in Southwestern Indiana: a Long-Term Study

Abstract

From 1994 to 2015, the spawning biology of two populations of spottail darters (Etheostoma squamiceps) was monitored using artificial nest sites in two first-order streams that are part of the Bayou Creek drainage in southwestern Indiana. During the mid-March to May breeding season, size (standard length) of breeding individuals of both sexes captured under nest sites was measured, and the presence of eggs was noted. In addition, laboratory experiments examined the relationship between female size and both the number of mature ova and the number of eggs spawned. Larger males spawned earlier and were more likely to be defending eggs throughout the breeding season; larger females also spawned earlier. Both the number of
mature ova and the number of eggs spawned varied positively with female size; however, for females of the same size the number of ova was consistently greater than the number of eggs spawned, suggesting that spottail darters are fractional spawners. While female size and spawning statistics were similar to those of an Illinois population, males in the current study were much larger than their counterparts in Illinois, which may be due to either more rapid growth or a longer lifespan.