The Effects of Rearing Temperature on American Glass Eels (Anguilla rostrata)

American eels are declining throughout their range requiring a better understanding of physiological requirements of all life stages and optimal conditions for laboratory rearing and aquaculture. American glass eels (Anguilla rostrata) were housed for 3 weeks at 14, 18, 22, or 26 °C to determine optimal juvenile rearing temperature in the lab. All treatments exhibited weight gain over the course of the study except the 14 °C treatment; however, there were only marginal differences in final weight between the 18 and 14 °C treatments and no differences in length. Variation in length and weight generally increased as temperature increased with significant differences in the standard error of weight between 14 °C and the 22 and 26 °C treatments and between 18 °C and 26 °C. Mortality was significantly greater than expected by chance at 26 °C (7 deaths) and no mortality was observed at 14 °C. Body condition (Fulton’s K), conversely, was lowest in the 14 °C treatment. Considering all response variables, optimal laboratory rearing conditions were observed between 18-22 °C. Within a week of experimentation, evidence of gas bubble disease was observed and by completion noted in all treatments except at 14 °C, likely as a function of increased gas solubility at warmer temperatures. Levels of total gas pressure (103-108%) and ΔP (28-54mmHg) values may account for the gas bubbles observed.