by Ben Goldfarb
This spring, millions of Americans will snap together rods, tie flies and spinners to monofilament, and, from a boat or streambank, cast to a rising fish. In many places, their quarry will be the born-and-raised products of hatcheries, facilities in which fish are artificially bred for the benefit of anglers. Nevada will stock a million trout in its waters this year; Oregon, 7 million. Washington plans on releasing a remarkably precise 17,140,634 trout and kokanee. A few years ago, California turned nearly 50 million fish loose in its lakes and streams.
The latest evidence comes from Kristy Bellinger, a PhD candidate at Washington State University. Bellinger bred five separate lineages of cloned rainbow trout, from totally wild trout to fish whose ancestors had been hatchery-raised going back over 100 generations. She placed fish from each lineage in a tank and then startled them into “sprint speed” — the quick burst of movement that fish use to dodge predators and catch food. Typically, big fish are also the strongest and fastest, and Bellinger figured that the hatchery offspring, which had been bred for size for generations, would be the best sprinters.
But that’s not what she found. “As they grew bigger,” she says, “they were slower.” Fish that came from the highly domesticated line — the one descended from 100 hatchery generations — were sluggards; in fact, it was hard to get them to sprint at all. Other, slightly-domesticated lineages didn’t swim as poorly as the hyper-hatchery line, but were still slower than wild trout.
So what’s going on? A form of unnatural selection. “When hatchery managers select fish to be broodstock, they’re looking for big fish,” explains Bellinger. “They want the highest growth rate for their buck. But there’s a tradeoff there, where highly domesticated fish can no longer escape predators.”
The poor swimming abilities observed by Bellinger and other researchers may help explain the damage that hatchery fish are capable of inflicting on their wild cousins. In a collection of 23 papers published in 2012, authors from the U.S., Canada, Russia and Japan documented that hatchery salmon often outcompete wild fish for food and habitat. (Even if wild fish really are fitter, numbers are against them: an incredible five billion captive-raised salmon are released every year.) As wild salmon are squeezed out, so too is the genetic diversity that fish have evolved in response to local river conditions, replaced by traits selected in the artificial context of a hatchery. That might be part of the reason why spawning populations that contain higher proportions of hatchery fish experience less reproductive success.
“Compared to a streambed, the hatchery environment is like being on the moon,” says Michael Blouin, a professor of biology at Oregon State University whose research has shown that hatchery-raised steelhead — sea-run rainbow trout — can lose up to 37 percent of their reproductive abilities in a single generation. “A trait that would make you grow fast in a concrete tank while eating pellet food with 50,000 other fish would serve you well in a hatchery. But that trait might not help you in the wild.”
New knowledge about potential hatchery problems has led to conflict within the fish management community, where hatchery policy remains controversial. Last week, Washington struck a blow in favor of wild fish, designating three Columbia River tributaries — the East Fork of the Lewis River, the North Fork of the Toutle/Green River, and the Wind River — as some of the state’s first wild steelhead gene banks, waters into which no hatchery-raised steelhead will be released. The three rivers will eventually be part of a statewide network of gene banks designed to protect and restore steelhead, which have been listed as threatened in Washington since 1998. The Sol Duc River has also been designated, and gene banks on the Puget Sound are slated for creation in the coming months.
“Research indicates that when wild and hatchery fish mix together on spawning grounds, there can be negative impacts through interbreeding and competition,” explains Bryce Glaser, a biologist with the Washington Department of Fish and Wildlife. “The rationale was to set aside some places that are free from those risk factors, so that steelhead can better respond to the other threats they face.”
While gene banks represent one promising solution, Bellinger points out that hatcheries aren’t inherently destructive. Fish-breeding facilities that use local, genetically diverse broodstock and take pains to mimic wild conditions often produce better results. And for critically endangered salmon populations, hatcheries may be the only answer. The Nez Perce tribe, famously progressive in their hatchery management, have boosted Snake River fall chinook returns to 56,000 fish — well short of the half-million chinook that once spawned in the Snake, but a remarkable improvement from the meager 600 that annually returned during the 1980’s.
At most hatcheries, however, enlightened tactics haven’t yet infiltrated policy. “The answers are clear,” says Bellinger. “But it feels there’s a link broken in the chain between science and management.”
This article was originally published in High Country News (hcn.org). The author is solely responsible for the content.