Managers speculate effects of cold winter on salmon survival

The Fish Site
by The Fish Site
19 April 2007, at 1:00am

US - Fishery managers do not know for sure how this long, cold winter and slow start to spring will affect salmon numbers over the next few years, but they have a good idea of the possibilities based on past data.

Pre-emergent fry studies took place in Kodiak from the late 1960s, but a lack of funding cut the program several years ago.

The program allowed Alaska Department of Fish and Game biologists flying to various river systems and excavate areas where pink salmon spawned to see how well the fish survived over the winter.

“You could tell whether floods in the fall had washed the eggs out completely and if the fry were developing normally, or if there had been a problem because of freezing,” Kodiak Regional Aquaculture Association (KRAA) executive director Kevin Brennan said. “Those are the kinds of things that make the survival of pink salmon much more iffy.”

Brennan, a former Fish and Game fisheries biologist, said he participated in the program.

In comparison to other winters, this past winter and early spring has been one of the colder on record, he said.

“We had years of low salmon production in the ’70s in and around Kodiak. Part of that was ascribed to some of the colder temperatures we had back then.

“This March was very similar to some of those very cold winters we had in the ’70s. There is the potential it is going to affect the pink salmon production specifically, and possibly some of the other species of salmon,” he said.

This will not affect this years’ pink salmon run, but the 2008 run could be impacted.

Brennan noted pink salmon are the least evolved salmon species and more likely to be affected by climate. They often spawn in shallow water and gravel with a lot of water in it and are subject to freezing.

“Salmon eggs in the gravel can take a small amount of freezing and thawing, but if they get totally frozen or enclosed in ice, or if there is ice anchored to the stream bottom when they are trying to out-migrate from the gravel, then they just don’t survive,” he said.

Source: Kodiak Daily Mirror