Evaluation of Thermal Requirements for the Propagation and Recovery of June Suckers

摘要

Determining the optimal rearing temperature for the June sucker Chasmistes liorus has been identified as a key component necessary for the design of a new June sucker hatchery and for achieving the June Sucker Recovery Implementation Program supplementation goal of 350,000 fish of 20-cm length annually. A laboratory study was conducted to monitor the performance of June suckers reared at average temperatures of 8.3, 10.1, 12.3, 14.0, 16.1, 18.5, 20.5, 21.8, 23.9, 25.9, 27.9, and 29.7 degree C for 16 weeks. In this study, quadratic regression analysis was used to determine maximum condition factor and weight gain, respectively, and 22.5 degree C and 21.9 degree C were identified as the maximum water temperatures. According to this same regression analysis, the maximum feed efficiency and total length increase occurred at 21.6 degree C and 23.7 degree C, respectively, during the 16-week study. The modified acclimated chronic exposure water temperature (50% survival for 60 d) was greater than 27.9 degree C. Spinal and fin deformities increased during this study in all treatments, and these malformations appear to be diet related. There was no temperature effect on deformities, but temperature did affect overall survival.