John Driscoll/The Times-Standard
Posted: 12/13/2010 01:29:28 AM PST
After several years of steady declines, Freshwater Creek's salmon appear to be on the upswing.
With the peak of the salmon run still two weeks away, biologists at the Freshwater weir and trap have seen more fish than they did all year in 2009-2010. The coho and chinook salmon are big and healthy and their numbers are a positive sign after the past few depressing years.
”There's some chinook in there the size of a full-grown pig,” said retired Humboldt State University fisheries professor Terry Roelofs. “Well, not quite.”
The larger numbers are promising, Roelofs said, and reflect good runs in many -- though not all -- other North Coast watersheds.
As of Friday, biologists had trapped and counted 122 coho, 12 chinook and a steelhead -- the steelhead run is later than the others -- a monumental improvement over last year's pitiful numbers. Five of the chinook have measured 40 inches or more and upwards of 40 pounds.
During the 2009-2010 season, in which the trap was operated from late October to May, there were only 70 coho, three chinook and 25 steelhead counted. Those are the lowest numbers since Fish and Game took over the count in 2000.
”For this time of year we're seeing a good number of fish,” said Colin Anderson, an HSU biologist working with Fish and Game.
If the trend continues this year, the numbers would still fall below the banner run of 2001-2002, when Fish and Game trapped 707 coho, 122 chinook and 76 steelhead. But it would be a significant improvement after years of decline.
Because heavy rains can overtop the weir and allow fish to swim past, biologists estimate that the number of fish captured represent about 60 percent of the fish that actually make it upstream to spawn. Fish and game tags a number of juvenile fish before they migrate into Humboldt Bay and into the ocean, then records how many of the tagged fish return to Freshwater Creek to spawn. That number gives biologists an idea of how many salmon survive at sea, which can help them understand whether there is ample food in the marine environment, said Fish and Game Associate Fisheries Biologist Seth Ricker.
For the coho salmon smolts that migrated to sea in 2007, then returned as 3-year-old adults, marine survival was estimated at a meager 2.6 percent. The 2008 smolts fared even worse. Ricker said that only 0.85 percent of coho tagged made it back from the ocean. Scientific literature puts typical marine survival at between 1 and 20 percent, he said.
This year's apparent rebound suggests that ocean conditions were likely good while salmon were at sea, Ricker said, which may also be reflected in the strong runs of salmon appearing in a number of other coastal streams and rivers like the Smith River, Redwood Creek and the Eel River this year.
”I presume we're getting something of a rebound because that marine survival rate is going up,” Ricker said.
In general, however, Ricker said that coastal coho and chinook populations are flagging over the long term. Salmon populations rise and fall naturally. Healthy populations can weather downturns due to poor ocean conditions and poor spawning and rearing conditions in freshwater, Ricker said, while struggling stocks can suffer severe damage during those tough years.
John Driscoll covers natural resources/industry. He can be reached at 441-0504 or firstname.lastname@example.org.