Incubating salmonid eggs not only develop over time but also according to temperature. Eggs incubated at 10 C° develop twice as fast as eggs incubated at 5 C°. To keep track of the development within an egg, scientists have a system that uses Accumulated Thermal Units (ATU).

Simply put, 1 ATU is one degree for one day. In water of 10 C°, we would accumulate 10 ATU per day, after 13 days we would have 130 ATUs, if the water was five C°, in 13 days we would have 65 ATUs.

For a listing of predicted ATU's and an ATU Calculator visit ^*

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