David Welch's theory on the decline of the coho is giving fishery managers nightmares


IT'S all so very confusing. First, federal Fisheries Minister David Anderson imposed sweeping conservation measures designed to rescue endangered B.C. coho. Next, an independent panel of fisheries experts called on the federal and B.C. governments to quit their squabbling and give "absolute priority" to the protection of salmon habitat "before it's too late." Now, word has spilled out from a research lab run by the federal Department of Fisheries and Oceans in the little Vancouver Island city of Nanaimo that it just doesn't matter.

Cut fishing quotas, buy out boats, preserve every last salmon stream from clearcutting, and B.C. salmon may still become extinct thanks to global warming. That's the interpretation being put on a study by the head of DFO's High Seas Salmon Research Program, David Welch, scheduled to appear in a forthcoming edition of the Canadian Journal of Fisheries and Aquatic Sciences.

News of Mr. Welch's paper first appeared in the form of a commentary in the prestigious journal Science. When that hit the streets last week, news outlets across the country began making a beeline for the little peninsula in Nanaimo harbour that is home to the DFO's Pacific Biological Station. Mr. Welch tried staging a strategic retreat to his own house nearby, but to no avail.

Even as he sat down in the kitchen to explain his findings once again-tills time to The Globe and Mail - another camera crew arrived hoping to get an interview in time for the evening newscast.

"If I'd had my choice I would have waited a couple of weeks to publish, until the current crisis had died down a bit," said Mr. Welch, "but the publishers decided to run their article on their schedule rather than mine. It's wreaked havoc."

SMALL wonder. For if the actual substance of Mr. Welch's report is slightly less apocalyptic than its advance billing suggests, it is nonetheless the stuff of nightmares for fisheries managers.

After eight years of cruising around the North Pacific and some extensive trawling through historical salmon-research data, Mr. Welch has come to a simple yet profound conclusion: Salmon can't handle heat.

It was something he first noted on a research cruise in the Gulf of Alaska in the spring of 1990. There seemed to be sharp limits to where salmon would travel, dependent on water temperature.

Intrigued, Mr. Welch hooked up with a Japanese research team and, in 1992, took part in a midwinter trans-Pacific research survey, the first of its kind and the last he ever wants to do. "There were waves 50 feet high. One day the wind topped out at 150 kilometres an hour."

Once again, he found that the salmon were rigidly confined within water of a particular temperature range, this time seven degrees Celsius or colder.

"That was really surprising," said Mr. Welch. "We actually got back on Christmas Day and started to pull all of the old data, and sure enough we saw the same thing in the past." In fact, according to Mr. Welch's paper, the pattern is entirely consistent over 40 years of research data and 21,000 different sampling locations. The reason no one had ever seen it before, he said, is because the exact temperature forming the boundary varies over the course of the year. "In winter it's about seven Celsius for sockeye - our most commercially valuable species- and by summer it's around 2 or 3 Celsius. So if you just plot numbers of salmon versus temperature you get a shotgun pattern, but break it out by months you start to see this sharp edge." The kicker comes in the final section of the paper, where Mr. Welch peers into the future using the best available climate medels to see where these regions of cold water will be in a world with double the current atmospheric concentrations of carbon dioxide. By 2050, he found, there won't be any in the North Pacific at all. His model predicts the zones with water cool enough for salmon will have retreated all the way up to the top half of the Bering Sea.

NOTHING at all is said in the paper about the current declines in salmon stocks, although Mr. Welch clearly finds the question intriguing.

"The climate models predict global warming will start to kick in in the early 1990s," said Mr. Welch, "and certainly in the Eastern North Pacific we're seeing ocean temperatures higher than anything we've seen in the past 50 years. We're also seeing a significant decline in ocean survival of steelhead trout and coho salmon. Both are due to some sort of change in the ocean. Both are happening at same time, but we don't know if they're directly linked, and we certainly can't say if they're due to global warming."

It's also too early to judge what the scientific community's response to Mr. Welch's study will be, but for some at least, it's all too convenient.

"I'm suspicious of anything, especially anything by a DFO researcher, that lets DFO off the hook for overfishing," said David Ellis, the executive director of the conservation-minded Fish for Life Foundation. "The figures show that coho stocks have been declining since the '50s, and all the while DFO was allowing catch levels to rise."

But Louis Tousignant is a little more circumspect in his evaluation of Mr. Welch's work. That's only to be expected considering it comes from a former federal regional director-general of fisheries and the chairman of the eight-person panel that last week released a report calling for a radical new commitment to salmon habitat preservation by federal and provincial governments.

"The article has yet to be published so I don't know what it really says," Mr. Tousignant commented, "but I don't think that anyone has enough evidence to say that in X years the resource will be going down the tubes. Temperature regimes in the North Pacific have fluctuated historically. We are now in a warmer period, but we will see it is cyclical. What's important is to make sure that when ocean conditions improve that we will have kept enough productive habitat to ensure that the resource rebounds."


T0 that end, Mr. Tousignant recommends, among other things, that all three levels of government co-operate to form committees of experts and local people to manage and protect key watersheds. He also calls on the provincial government to begin implementing the sections of the Forest Practices Code designed to prevent forestry companies from logging right up to the edges of fish-bearing streams.

Mr. Welch doesn't disagree with any of this. "'What we're saying is that very clearly you have to look at the whole life cycle of salmon, and not just the part they spend in fresh water. So if you fill in the rivers there will be no salmon. But if you fill in the ocean, which is to say it you don't cut back on greenhouse gas emissions, there will also be no salmon."

Does this mean it's all over for the Pacific salmon? No, said Mr. Welch, but it does mean that salmon will have to be considered in any debate on whether or how quickly to reduce greenhouse gas emissions.

"'What we're trying to do scientifically," said Mr. Welch "is say that if global warming is real - and just about anyone responsible believes it is - what are the negative consequences of continued CO emissions going to be, because there's no doubt that cutting back on CO emissions is going to cost us economically. What we're saying here is that not cutting back will also have costs."

One of which may be salmon.


Shawn Blore is a Vancouver writer.