Predicting salmon runs — and reporting the issuesMarch 3rd, 2011 by cdunagan
Before salmon managers begin to focus on harvest quotas and seasons for salmon fishing, they must work out predictions about the number of salmon coming back to each management area throughout the Northwest.
So how do the managers go about predicting this year’s salmon runs? It gets pretty technical, but it is basically a combination of counting the number of salmon smolts that leave selected streams and then calculating a rate of survival to determine the number of adults that will come back.
Numerous conditions affect whether eggs and fry will survive to smolt stage and make it out of a stream, just as many factors can cause the death of the young fish after they leave freshwater. I’m tempted to describe these factors here, but instead will defer to Mara Zimmerman, who heads the Wild Salmonid Production Evaluation Unit. Her well-written report on the “2011 Wild Coho Forecasts…” (PDF 376 kb) provides an excellent education into how coho are estimated. Check it out.
I was one of three newspaper reporters who attended Tuesday’s meeting in Olympia. It was easy to tell the difference between my handling of this story and the approaches by Jeffrey P. Mayor, who writes for the Olympian and the News Tribune in South Puget Sound, and Allen Thomas, who writes for the Columbian in Vancouver (Clark County).
The biggest difference is that those guys are sports or outdoor reporters, mainly interesting in telling their readers what fishing will be like this year. As an environmental reporter, my primary focus is to describe how the salmon are doing ecologically — although I do recognize that many readers of my stories are anglers who also want to know about fishing.
I tend to examine the effects of commercial fishing more than most reporters, and that means a focus on chum as well as pink salmon.
Another difference is escapement. While outdoors reporters strive to tell their readers about the number of fish available to be caught, I am equally interested in reporting on the number of salmon that make it back to the streams to spawn. Those reports mostly come in the fall, when we find out if harvest managers have allowed enough fish to survive the gauntlet of fishing lines and fishing nets.
Another difference is the focus on species. Chinook, or king salmon, are probably of greatest interest to most anglers. But chinook streams on the Kitsap Peninsula and Hood Canal — my home turf — are fairly limited. It is the coho, or silver salmon, that tell us if we are protecting our streams well enough to produce the next generation of fish. Coho are a good indicator of ecological health, because they spend more than a year in freshwater before swimming out to sea.
Another story I’m always interested in telling is the tension between the desire to catch fish for their sport and economic benefits — which involves dividing the harvest among recreational, tribal and non-tribal commercial fishers — and the need to conserve enough adult fish for spawning. As salmon declined through the years, I noticed that most people at the North of Falcon meetings were paying more attention to conservation. But the listing of chinook as threatened under the Endangered Species Act created a stronger voice for the federal government, which is beginning to take a strong stand to protect not only chinook but also endangered killer whales. Review my Water Ways entry for Saturday.
As I reported this week, increased numbers of wild coho are a good sign, but they will increase the challenge in managing the selective fishery.