Federal fisheries experts say the lower-than-expected number of sockeye salmon returning to the Fraser River this year may be attributed largely to the ocean water being unusually warm.
But the experts cannot figure out how to modify their preseason forecasts to reflect the impact of warmer oceans.
Commercial, recreational and first nations fishermen rely heavily on preseason estimates from the federal Department of Fisheries and Oceans to plan for the size of catch they can anticipate each summer.
Based on federal estimates, fishermen on the Fraser River expected a strong season. The Fisheries staff forecast summer sockeye salmon at 11 million.
So far, the run has been so low that the government has prohibited commercial and most recreational fisheries on the Fraser and restricted fisheries by first nations, whose members have first priority after conservation needs are met. Federal officials now estimate the summer sockeye run could be as few as two million.
Extensive monitoring of ocean temperatures has indicated the water in some spots was as much as five degrees warmer than normal, Michael Foreman, a research scientist with the department’s Institute of Ocean Sciences in Sidney, B.C., said yesterday.
Scientists have figured out how the warmer water affects the migration pattern of the salmon. But fishery officials do not know precisely what effect the warmer water has on the salmon population. “It is very difficult to quantify exactly what the impact is going to be,” he said.
“We know it is a factor, and we are trying to improve our model to account for things like that. But this is new territory. It is not just us. All fisheries in the world have to come to terms with this,” Mr. Foreman said.
Paul Ryall, spokesman for fisheries management in the Pacific region of Fisheries, said officials do not have enough experience with salmon in warmer-than-expected water.
“How often have these events been relevant?” he said. “So far, it is rare, but our model is based on history. It’s not easy for us to forecast a rare event.”
Federal officials are trying to improve their forecast model, he added. “But until we see more of these events – and we don’t particularly want to – we cannot build it into the model.”
However, Dennis Brown, author of Salmon War, an account of disputes over the West Coast fishery in recent years, said federal officials may not have enough resources to do the job. The federal government “gutted the budget” and should restore the department’s funds for monitoring, he said.
He also urged officials to consider other explanations for the failure of the sockeye to show up as forecast. Environmental factors are a convenient excuse to rationalize such a huge variation from their predictions, he said.
Mr. Brown suggested officials consider whether conservation measures were too extreme and too many fish were put on the spawning grounds four years ago. The oversupply may have overtaxed the system, he said.
In an overview of the sockeye salmon fisheries, Mr. Ryall said that sockeye returns across the province and in Lake Washington, outside Seattle, were less than federal fishery officials had forecast.
The sockeye salmon run into Lake Washington was at 20 per cent of the forecast and the run into the Skeena River was at 41 per cent. Federal officials were closer to the mark on the Nass River and Barkley Sound, on the west coast of Vancouver Island.
On the Fraser River, 81 per cent of the Early Stuart sockeye salmon showed up but only 35 per cent of the Early Summer sockeye. Mr. Ryall said it was too early to say how far off base their forecast was for the Summer sockeye and Late sockeye.
Ocean waters have been gradually warming in coastal and deep-sea regions of the Gulf of Alaska. Sockeye in the Fraser River this summer were in the Pacific Ocean in 2003, when the water was much warmer than previous years, Mr. Foreman said.