Effects Of Chronic Thermal Stress On Tolerance and Growth Of Channel and Hybrid Catfish

Global climate change is a growing concern for pond culture due to possible exacerbation of temperature fluctuations and increased maximum daily temperatures. Channel catfish (Ictalurus punctatus) have a broad natural distribution from southern Canada to northern Mexico. It was hypothesized that natural differences in thermal tolerance and seasonal growth may be attributed to different geographic strains, as well as hybrid catfish (I. punctatus x [blue catfish] I. furcatus). To examine this, we quantified chronic thermal tolerance and growth rate of two geographically distinct strains of channel catfish and the corresponding industry standard blue catfish hybrid cross. In a six-week growth experiment, catfish were subjected to daily cycling temperatures of either 27-31°C or 32-36°C to mimic pond fluctuations. Hybrid catfish had the greatest survival and all channel catfish at 27-31°C had greater growth, with weight gain greatest in southern channel strains and length gain greatest in northern channel strains. Conversely, temperatures of 32-36°C resulted in reduced growth regardless of geographic strain of channel catfish.  Hybrid catfish appear to be more resilient to temperature changes, although they grew more slowly than channel catfish.