Efficacy of Packed Column Designs for Reducing Mortality of Rainbow Trout Eggs and Fry

Abstract

Abstract An experiment was performed to determine the effect of open and closed packed columns on dissolved gas levels and on mortality of eggs and sac fry of rainbow trout (Oncorhynchus mykiss) at Neosho National Fish Hatchery from March 9 to April 9, 1993. Two water treatments were tested: (1) treatment with a sealed column packed with 1 -in Koch rings and oxygen injection, and (2) treatment with an open column packed with 1 -in Koch rings. Untreated springwater was tested for comparison. Statistically, rainbow trout reared in untreated springwater had significantly higher mortality (P < 0.05) than trout reared in both packed column treatments; mortality did not differ significantly between column treatments. Total dissolved gas saturation in all three groups remained below 100% and did not influence mortality. Untreated springwater had the highest mean nitrogen saturation (103.5%), which may have contributed to egg and fry mortality. Water in the open packed column and in the sealed packed column with ...