Pacific Salmon: The Forbidden Topic

Let me state for the record that I love Pacific salmon ? a truly remarkable gift of nature?s design. I particularly love them in their natural habitats. They are an integral part of the amazing way natural systems work in the Pacific Northwest. For example, their post-spawning bodies leave behind scarce deep-ocean nutrients that are essential to the forests where their spawning headwaters originate. In turn, the new generation carries forest nutrients to the ocean in a remarkable cycle of ecosystem interdependence that keeps nature?s design humming along. The salmon and forests evolved together and wove this complex set of functions and relationships to mutual benefit.

When Pacific salmon were plopped into Lake Michigan in 1966 I don?t think anyone was considering their evolutionary ecosystem function. I think Howard Tanner of Michigan?s DNR was thinking they?ll eat the alewives and be fun to catch. The salmon sport fishery has since became so popular and generated so much tourism money that it is practically blasphemy to raise the question of whether, after 40 years of a ?short-term? experiment, Pacific salmon belong in the Great Lakes.

I don?t want to anger any charter boat captains or people who love to haul these flashing beauties out of the lakes. Everyone seems so afraid of a backlash from the sport fishing community that you can hardly bring this topic up at a Great Lakes conference without people fleeing for the doors. But, I do think it is a topic that bears a serious discussion within the scientific community and among the larger communities who have a stake in what lives in the Great Lakes, and how we manage the lakes as a result.

Nutrients play an important role in the salmon life cycle. Apparently ?you are what you eat? applies to salmon as well as people, and a diet rich in Great Lakes alewives and rainbow smelt (two other non-natives but from a different ocean) leaves you with a thiamine deficiency. Our Great Lakes foodweb no longer has its native diversity, nor does it mimic the ocean?s diversity. What some have termed the Great Lakes salmon ?junk food diet? leads to Early Mortality Syndrome, (EMS) which means many of the fish die young. This is such a serious problem for Great Lakes predator fish that many hatcheries have apparently taken to dipping the wee salmon fry in a thiamine bath of sorts before they head out to fend for themselves in the lakes. (You can read more about this at http://www.glsc.usgs.gov/main.php?content=research_initiatives_thiamine&title=Initiatives0&menu=research.)

For me, it raises the question ?How wild is a hatchery born, thiamine-dipped salmon, whose genes yearn for the ocean and Douglas fir forests, and to what extreme efforts must we go to keep this strange fishery going in the Great Lakes??

Maybe I?m just being unrealistic and nostalgic about the native lake trout. Maybe hatcheries and dips are the best we can do as we grapple with the bizarre mix of creatures from throughout the globe that now represent the biomass of the Great Lakes. Still, it seems like it is well past time to engage in a healthy public dialogue on the role of native vs. non-native fish in any serious plans to restore the ecosystem, and to consider how either choice relates to efforts to grapple with the invasive species that are dismantling what is left of the natural foodweb. I?m not saying it will be pretty, but I think we need to have this discussion.