Friday, April 25, 2008

Maybe, Salmon are just Salmon?

Sometimes in the midst of the vast uncertainties that nature always presents us—a reminder of our rather limited human powers—it may make sense to just rely on common sense.

Salmon might just be salmon, whether hatchery raised or wild, just as cows are cows and horses are horses, and they will find their way to spawning beds, reproducing their species, regardless of their status at birth.

Salmon tags to reveal if hatcheries help or hurt
State-bred fish tracked to see if they're pushing wild ones out of picture
By Matt Weiser -
Published 12:00 am PDT Friday, April 25, 2008

Hoping to engineer their way out of a salmon crisis, wildlife agencies are manipulating the natural rhythms of the species to an unprecedented degree in hopes of producing more fish.

California has long trucked most of its young hatchery salmon around the Sacramento-San Joaquin Delta to avoid losing them to pumps, poisons and predators. This year, under pressure from fishing groups, it will truck nearly all of them – nearly 17 million salmon smolts.

Federal officials will also truck about 10 percent of the salmon produced at their hatchery near Redding. They haven't trucked fish in more than a decade, and then only as a test. This year, those fish will ride nearly 200 miles to reach San Pablo Bay.

The hatcheries were created to replace spawning habitat eliminated by dams. But this year's changes are prompting important questions about how the hatcheries themselves affect salmon survival.

Fisheries experts have worried that trucking salmon around their home rivers breeds out the instinct that draws fish back to the right place to spawn – an instinct that defines the species.

"Are hatcheries supposed to be helping fish recover over time or just pumping out fish for fishermen to catch?" asked Rachel Barnett-Johnson, a fisheries biologist at the UC Santa Cruz Institute of Marine Sciences. "That's where the struggle lies in managing them now."

Barnett-Johnson published a study this month that found 90 percent of the salmon caught in California's ocean fishery are hatchery-raised, and only 10 percent are wild spawners. She analyzed growth patterns in fish ear bones, which look like tree rings.

Her results, based on a limited sample of fewer than 200 chinook, alarmed fisheries experts. Many assumed, again based on limited information, that wild salmon still make up 50 percent or more of the state's chinook population.