Impacts of water quality and hand-picking of dead eggs on the survival of brown trout and Atlantic salmon eggs

The effect of water source and removal of dead eggs by hand on egg survival of brown trout Salmo trutta and Atlantic salmon S. salar was studied experimentally in a hatchery trial, which started from fertilization in October and lasted until egg eye-up in early March; no antifungal chemical treatments were used. The experimental treatments were water source (surface water, filtered surface water, or groundwater), species, and hand-picking of dead eggs (used, not used); we used four replicates per treatment, resulting in 48 batches. Incubation of eggs in groundwater yielded higher egg survival to eye-up than incubation in surface water or filtered surface water. Hand-picking of dead eggs enhanced survival of eggs incubated in surface water but not those incubated in groundwater. The best combination for egg survival in both species was the use of groundwater incubation without hand-picking of dead eggs.