June 14, 2008

Salmon Disease Blamed on Warner Climate

An expert on fish disease blames warmer water in the Yukon River for a parasite that has been killing Alaskan salmon.

The problem is white spot disease, which is caused by Ichthyophonus hoferi, a parasite that has played havoc with herring stocks in Scandinavia, the Los Angeles Times reports. Fish infected with the parasite do not smell right when caught, have flesh that turns mealy and do not cure properly.

Richard Kocan of the University of Washington, who began studying salmon in the Yukon in 2005, said that 25 percent to 30 percent of the salmon were infected near the mouth of the river and at the halfway point of the their journey upriver to spawn. He found that the percentage of infected fish was much smaller in the spawning area, he believes because many of them died and sank to the bottom.

Kocan suggests that the disease appeared in the 1980s because the Yukon is warmer, with the ice breaking earlier every year and water temperatures rising higher.