Raisin' Fish: Dang it's cold

Seattle is in the grip of a major cold wave along with most of the northern half of the US. Normally we are sheilded from that by the Japanese current and being at sea level more or less, but not this time. It has been below freezing for several days now.

Water flow through my icubator is stll moving, but not at the rate it was before the cold set in. I hope that I don't end up with any frozen pipes. I shouldn't as long as the water keeps moving. One thing this will do is slow down the maturation process of the eggs/alevin.

The timetable for salmon maturation from egg fertilization through release is fairly well documented and based on what are call "thermal units." One thermal unit is equal to 1 degree above 32 Farenheit for 24 hours. From fertilization to hatch is 750 thermal units; from hatch to release is 1,000 thermal units. I got my eggs early because of two factors; the fall run of coho salmon at Issaquah Creek hatchery was earlier than usual, and the water temperatures there were a bit higher than normal (causing the eggs to reach the 'eyed' stage earlier).

Water is not all that quick to respond to air temperature changes; it generally varies much more slowly than the air above it. I haven't ever measured the water temp in McAleer Creek, but have guessed it to be about 42 degrees (more or less). That gives me about 100-105 days from the time I get eggs in the incubator until I release them. The water going down a degree or even two would only slow that rate by a couple of days at most, so I'm guessing that fish release will still be some time around the end of March 2009.

I watch the outflow from the incubator a couple of times a day. As long as it is still flowing, my babies are going to be happy. So far, they are happy.