Effects of Temperature on Egg Production and
Early Stages of Fountain Darters

TIM H. BONNER AND BOBBY G. WHITESIDE (Aquatic Station, Southwest
Texas State University, San Marcos, Texas 78666)

TOM M. BRANDT AND JOE N. FRIES (National Biological Service, National
Fish Hatchery and Technology Center, San Marcos, Texas 78666)

Studies were conducted to determine the effects of water temperature on egg and larval production, percent hatch, and larval survival of the endangered fountain darter Etheostoma fonticola. Adult fish were exposed to water temperatures of 14, 17, 20, 23 (control), 25, 27, and 29°C for 33 d. Egg production was significantly lower for fish held at 27 and 29°C than fish held at 23°C. Percent hatch was significantly lower for fish held at 14, 25, 27, and 29°C than fish held at 23°C. Larval production was significantly lower for fish held at 25, 27, and 29°C than fish held at 23°C. Lethal temperatures for 50% mortalities (LT5024) of 24- to 72-h old larvae were estimated at 3.8 and 31.9°C.

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