Escaped Salmon a Threat to Endangered Orcas’ Food?

  Tribal fisherman Larry Peterson, left, and Mike Bartlett, a nontribal resources worker, haul in a net Thursday [December 7] on the Skagit River. (Alan Berner/The Seattle Times)

Tribal fisherman Larry Peterson, left, and Mike Bartlett, a nontribal resources worker, haul in a net Thursday [December 7] on the Skagit River. (Alan Berner/The Seattle Times)

     The Upper Skagit Indian Tribe has found some of the farmed Atlantic salmon in the Skagit River three months after the fish escaped. This is after repeated assurances that the farmed salmon wouldn’t last long in the wild. The problem is twofold. They may compete for what wild chinook salmon normally eat. More importantly, and more troublesome, is the threat of them cross-fertilizing with the wild salmon and playing unknown havoc with their gene pool.

 Upper Skagit River Tribe Photo

Upper Skagit River Tribe Photo

    Four Watersheds
    
 I’ve been writing about how the lack of wild chinook salmon is a threat to the endangered resident Orcas. Wondering if this farmed salmon invasion will affect the Orcas’ food, I tried to sort out where their wild salmon diet normally comes from.
     Remember that adult salmon swim upstream to the very rivers where they were born to lay and fertilize their eggs. In the Northwest, it is generally agreed that the salmon feeding the So Resident Orcas have come from four main rivers: the Skagit, the Snohomish, and the Columbia in the U. S., and the Fraser in Canada. The Center for Whale Research estimates that 50% of their diet is from the Columbia River basin and 25% from its Snake River system tributaries.

chinook2001_dist_map.jpg

Unintended Consequences
     Of the remaining 50% of their diet, it’s likely that at least some comes from the Skagit River watershed. We’ll have to wait for the upcoming salmon runs and the watchful eyes of fishing folk and conservationists. They are the ones who will see how the invasion of farmed fish affects the wild chinook of this river and perhaps others as well.
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