Pond Rearing of Juvenile Lake Sturgeon

摘要

Pond rearing of age-0 lake sturgeon could provide an alternative to intensive rearing of juveniles in a hatchery setting. We conducted a series of six pond and raceway experiments and nine laboratory experiments to evaluate factors related to pond rearing. We measured survival and growth of age-0 lake sturgeon stocked at different densities into 0.25-ha earthen ponds and outdoor raceways. In the first pond experiment we observed 100% mortality of the age-0 lake sturgeon. Subsequent experiments were conducted to determine the causes of mortality and improve survival. During summer months, pond water temperatures exceeded 25 degrees C on many days. In several experiments lasting 2-4 months, pond survival of the juvenile lake sturgeon never exceeded 5%. High water temperatures were probably the main cause for the poor survival of juvenile lake sturgeon in these ponds. In one raceway experiment we found 81% mortality during the first 14 d, but water temperatures were only above 20 degrees C for a few hours. We conclude that high water temperature was not the cause of mortality in the raceways. To evaluate the role of predation as a source of mortality observed in our outdoor experiments, we conducted several lab experiments with crayfish and largemouth bass, two main predators in our system.