Effects of cadmium on yolk utilization, growth, and survival of Atlantic salmon alevins and newly feeding fry.

Abstract

Growth and the yolk-to-embryo gross conversion efficiencies were determined for Atlantic salmon (Salmo salar L.) alevins and fry reared under control conditions and at 0.2 and 2.0 ppb cadmium (Cd). Alevins reared at 2.0 ppb Cd grew more slowly than controls and alevins reared at 0.2 ppb. The size reduction was due primarily to reduction in yolk-conversion efficiency during the latter half of yolk absorption. The rate of yolk uptake was also reduced at 2.0 ppb Cd. Mortality of feeding fry reared up to one month at 2.0 ppb Cd was 80 to 90%. Fry previously reared in 2.0 ppb Cd as alevins experienced lower mortality than those introduced to Cd at start of feeding. Mortality was preceded by hyperactivity and convulsions; 30 to 60% of fry exposed to 2.0 ppb Cd developed cranial swellings. Growth of fry surviving 2.0 ppb Cd for one month was severely retarded. There were no adverse effects from 0.2 ppb Cd.