…it’s the natural populations of fish that biologists believe to be the most resilient to climate change…
Some five billion hatchery salmon and steelhead are released into the North Pacific each year, including fish from 155 salmon, steelhead and trout hatcheries in the Northwest. But it’s the natural populations of fish that biologists believe to be the most resilient to climate change, according to a series of oral presentations at the 145th American Fisheries Society conference in Portland.
With three treatments of fish production – segregated hatchery, integrated or conservation hatchery, and reserved areas for natural spawning only – it’s the segregated model that seems to be disappearing from use. Part of the reason may be the fitness of hatchery salmon, according to many of the speakers at the conference.
Neil Thompson of OSU said that hatchery-origin salmon have lower fitness or reproductive success than do natural-origin salmon. The fitness decline in steelhead, which he is studying, results from domestication, such as overcrowding in hatcheries. Hatchery broodstock make better broodstock than do wild broodstock used in a hatchery, “but those offspring do poorly in a wild environment.”
And, hatchery salmon may not be fit enough to face a warmer future, according to Charles Huntington of Clearwater Biostudies, Inc. The mortality rate between hatchery fish and wild fish in warm water is quite different, he said.
“Hatcheries are unlikely to be a conservation tool in the future unless the circumstances are dire,” he said. “The long term efficacy of conservation hatcheries in a changing climate is unknown.”
An Atlantic salmon hatchery on the River Tyne in northeast England was removed and habitat improvements on the river, not the hatchery, is given credit for the recovery of the river’s salmon, according to Nigel Milner or APEM Ltd, Bangor University.
Most coho hatcheries along the Oregon Coast have been removed and most coho salmon on the coast now originate from naturally-spawning populations, according to Ed Bowles, chief of the fishery division at the Oregon Department of Fish and Wildlife.
These are just snippets of three of the 47 oral presentations focused solely on the interactions between hatchery and wild salmonids, organized by Troy Brandt, fisheries biologist with River Design Group, and president of the Oregon chapter of AFS. The hatchery/wild presentations represented just one of more than 15 separate seminars at the nearly week-long AFS Conference, August 16 through August 20.
The conference included a trade show with 112 booths, a program of nine continuing education courses, 404 poster presentations, 2,172 oral presentations in 101 symposia and 39 contributed paper sessions. In addition, it featured 61 short films in the America’s Fish and Fisheries Film Festival. The conference was attended by 3,200 people from 32 countries.
Other seminars covered topics from salmon and steelhead to forage fish and lamprey; genetics and modeling; sockeye salmon; public relations; land and water use, just to name a few.
The seminar covering hatchery and wild interactions questioned whether segregated hatcheries still have a place in Northwest rivers and went on to focus mostly on the successes and dangers of supplemented populations from conservation hatcheries or on simply removing hatcheries, as they did in England and on the Oregon Coast.
Providing a contrast to the River Tyne and the Oregon Coast, 160 segregated chum salmon hatcheries on the island of Hokkaido in northern Japan are feeding a large commercial fishery. The hatchery system includes 160 hatcheries in 145 rivers along 2,746 km (1,706 miles) of coastline. Just 10 of the hatcheries are national: the remaining are run by private nonprofit salmon enhancement program associations.
“At the present, there is no evidence of any decrease of genetic diversity in chum salmon in Japan despite the intensive hatcheryprograms,” wrote Yasuyuki Miyakoshi of the Hokkaido Research Organization. However, there are some problems such as a distinct difference in return rates among regions and early runs of the salmon have increased while later runs are in decline, he continued.
Still, commercial harvest cannot continue without the addition of the hatcheries, Miyakoshi said.
Shuichi Kitada of Tokyo University pointed out that a result of hatchery programs on Hokkaido and Hanshu is altering run timing of chum salmon and return rates are falling. Yet, genetic diversity remains high compared with other North Pacific populations.
One river in which segregated populations of hatchery steelhead and spring chinook co-exist with wild populations, while remaining genetically distinct is the Klickitat River in southcentral Washington, according to Joe Zendt of the Yakama Nation Fisheries Program. One reason is that the wild fish spawn further up the river and they spawn at different times.
Some 64 percent of wild steelhead spawned in the middle or upper mainstem and tributaries beginning in mid-March, while 90 percent of hatchery steelhead spawned in November in the lower mainstem. Hatchery steelhead also spawned at a lower rate.
Fish produced by mitigation hatcheries – those that were built to mitigate for the construction of a dam, for example, that block migration for adult salmon and steelhead – are usually more difficult than with the Klickitat River to segregate from naturally spawning fish and may pose genetic risks for the naturally-spawning population.
This is the case for steelhead on the Willamette River. Endangered Species Act-listed winter steelhead are native, as are rainbow trout in the upper Willamette River; summer steelhead are produced at a hatchery in the upper river using broodstock from the Big Creek Hatchery in the lower Columbia River. Those non-native summer steelhead return to the river and many spawn.
A genetic sampling program at Willamette Falls in 2009-2011 found that 10 percent of the sampled fish were naturally-produced summer steelhead and 10 percent more were hybrids of summer and winter steelhead with greater than 20 percent summer steelhead ancestry, according to Marc Johnson of ODFW.
As a result of his study, Johnson observed that “winter steelhead are on a steady decline.”
Hokkaido, the Klickitat and Willamette rivers aside, most of the oral presentations were about removing or reforming hatcheries.
Kim Jones, retired from ODFW, said that in the 1990s some 60 percent to 70 percent of the spawning salmon in the Salmon River, which flows into the Pacific Ocean just south of Cascade Head in Oregon, were hatchery fish and that the population “failed all viability metrics.”
Coho salmon releases ended in 2007, he said, and the estuary was restored. “The number of returns after the hatchery was removed is similar to before and the population is now ‘maybe’ resilient enough for recovery.”
A small supplementation experiment run by the Yakama Nation on the Cle Elum River in the Yakima River Basin of eastern Washington generally mirrors the results of other conservation or integrated hatchery programs. The program is into its third generation of spawning in the natural environment, according to William Bosch of the Yakama Nation.
While the program has increased the number of fish, the harvest, the redd counts and the extent of the spawning grounds, it has maintained, but not increased, the number of natural origin fish. However, the ecological and genetic impacts of the supplementation program have been limited. Straying to other rivers has been negligible, for example.
Other findings, Bosch said, are that natural origin females had a slightly higher breeding success, while the breeding success of males seems to be equal among natural and hatchery fish. There were high rates of hatchery age 2 mini-jacks, but the rate of returns of age 4 and 5 adults was similar among hatchery and natural fish. Hatchery smolts did not increase levels of pathogens in natural smolts and the ecological interactions between hatchery and natural fish was within the program’s guidelines.
Another supplementation or conservation program, this one in Johnson Creek in Idaho, found that hatchery-reared females “had no detectible difference in fitness relative to natural-origin females, but hatchery-reared males had lower fitness than their natural-origin counterparts,” wrote Maureen Hess of the Columbia River Inter-Tribal Fish Commission in her program introduction. However, hatchery rearing yields fewer males.
She also said that the relative reproductive success of hatchery-reared fish mating with natural-origin fish were equivalent to those between two natural fish.
“Results suggest,” she wrote,” that supplementation with 100 percent local, natural-origin broodstock may be a practice that can successfully boost population size with minimal negative genetic impacts to wild populations.”
Conservation hatcheries may add fish to rivers and contribute to the recovery of some stocks in certain areas, but “density dependence is often strong enough to constrain recovery,” said Greg Ruggerone of the Independent Scientific Advisory Board. “We need to improve habitat conditions if we are to provide more fish.”
Habitat is especially important in the spawning to juvenile stages of the salmon life cycle, he added.
“Hatchery salmon contribute a large proportion of the fish and contribute to density dependence,” Ruggerone said. “At what level is supplementation outweighed by the demographic benefits?”
Abundance of hatchery salmon on the spawning grounds often exceeds carrying capacity, Ruggerone wrote in his program introduction. That leads to “unsustainable natural production and an inability to achieve an integrated hatchery approach – a key rebuilding strategy.”
The ISAB recommends balancing hatchery supplementation efforts with a river’s capacity, while improving the river’s habitat.
The ISAB released a report, “Density Dependence and Its Implications for Fish Management and Restoration in the Columbia River Basin,” in February. It found that salmon populations are experiencing “reduced productivity associated with recent increases in natural spawning abundance, even though current abundance remains far below historical levels.” The report can be found at:http://www.nwcouncil.org/fw/isab/isab2015-1/
(See CBB, February 27, 2015, “Independent Science Board: ‘Density Dependence,’ Diminished Habitat Constraining Salmon Recovery,” http://www.cbbulletin.com/433283.aspx)
The 11-member ISAB was established in 1996 by the Northwest Power and Conservation Council and NOAA Fisheries to provide on request independent scientific advice and recommendations regarding scientific issues posed by the respective agencies on matters that relate to their fish and wildlife programs. Columbia River Basin tribes were added as equal and permanent partners in the sponsorship of the ISAB.
The complete program for the AFS conference can be found at:http://2015.fisheries.org/wp-content/uploads/2014/07/AmericanFisheries2015_Digital_small.pdf