Prediction, from temperature, of eyeing, hatching and 'swim-up' times for salmonid embryos

SUMMARY. 1. The literature contains a number of curves relating time (days) required for median hatch (=D₂) to water temperature (T,°C) for the eggs of several salmonid fishes. There are relatively few data on the relationships between time to median eyed (= D₁), days) or time to median swim-up (= D₃, days) and temperature.
2. From published data, over most of the range 0-9.5°C, approximate relationships are D,=0.5D₂ for Atlantic salmon (Salmo salar L.) and D3 = 1.7D₂ for eight species of Salmo and Oncorhynchus.
3. Field and hatchery tests suggest that these are useful empirical models for approximate prediction of D₁ and D₃ from D₂ for most salmonids.