Fecundity and Spawning Frequency of Captive Tessellated Darters–Fractional Spawners

Abstract

In 1982–1983, 15 pairs of captive tessellated darters Etheostoma olmstedi proved to be fractional spawners and produced from two to eight clutches (19 to 324 eggs per clutch; mean = 158) between the last week of April and the first week of August, in northeastern Pennsylvania. Average clutch size for individual pairs ranged from 49 to 204. The total number of eggs spawned per pair ranged from 97 to 1,435 (mean = 727). Intervals between clutches ranged from 5 to 16 d (mean = 7.6) in troughs and pools and from 8 to 26 d (mean = 16.3) in cages in a cool, spring-fed creek. Spawning usually occurred during daylight. Eggs began hatching in 97 h at 25 to 26°C. In 1984, the left ovary of eight fish confined for various durations held from 2,790 to 5,365 eggs of a continuum of sizes; 85.3% of 29,210 eggs were 0.2 mm or less, the size retained after the spawning season. Egg complements from females spawning up to six clutches were virtually indistinguishable from those of prespawning females, indicating continual egg recruitment from the group 0.2 mm and smaller. Fecundity estimates based upon ovarian eggs in prespawners would have been much too high if all eggs had been counted and far too low if only ripe eggs had been included. Received November 12, 1983 Accepted November 7, 1984