Relative tolerance of some salmonids to acid waters

Summary

Experiments have been performed to study the tolerance of different species of salmonids to acid waters (pH 4.4–5.5). Brown trout (Salmo trutta L.), brook trout (Sahelinus fontinalis Mitchill), rainbow trout (Salmo gairdnerii Richardson), Atlantic salmon (Salmo salar L.) and hybrids between char species were stocked in small and medium-sized acid lakes and tested in tanks to compare their relative survivals. These species can be ranked in the order brook trout, brown trout, Atlantic salmon and rainbow trout, with brook trout as the most tolerant to low pH. Factors other than pH, such as genetic variability, age of fish, physical conditions and water quality may influence this ranking. More knowledge about the relative species tolerance to various ecological factors is needed.