The effect of acid water on the hatching of salmonid eggs

The survival of salmon Salmo salar , sea trout and brown trout Salmo trutta eggs in acid water in the range pH 3·5±7·0 was investigated over a period of three winters. The effects of fertilising the eggs in acid water at pH 4·0, 4·5 and 5·0, and dilution of the test media were also studied. There was considerable yearly variation in the numbers of eggs which hatched, but there were no marked differences between the three species in the tolerances of the eggs to acid water; pH 3·5 was lethal within 10 days to all the eggs, but at pH 4·5 and higher pH levels there was no obvious difference in hatching attributable to acidity.