Researchers with the North Pacific Anadromous Fish Commission (NPAFC) in Vancouver, B.C. Canada, said they anticipate including the latest hatcheries-related research in their upcoming 2023-27 science plan, in hopes that the data will be used to improve management to support salmon stocks.
“Scientists are focused on density dependent and carry-capacity issues to understand how salmon growth and survival are affected by hatchery and wild salmon abundance, and quantify the current limits to salmon production at each life stage,” the commission’s Executive Director Vladimir Radchenko said.
“The ability of the Pacific Ocean to produce salmon is not constant, and for the most part, the limits are not known,” he explained. “A general concern is that competition among different salmon populations may lead to lower growth and survival at high abundances, especially during periods of lower biological productivity.”
Much of the new information that’s anticipated to become available as 2023 unfolds was collected in the winter 2022 International Year of the Salmon (IYS) high seas expedition. Participants included scientists from the U.S., Canada, Japan, the Republic of Korea, the Russian Federation.
NPAFC officials noted that due to anthropogenic pressures on ecosystems and associated anomalous events in the North Pacific Ocean, Pacific salmon are progressively being exposed to conditions outside normal climate cycles.
Alaska Department of Fish and Game (ADF&G) hatchery program managers have said that the number of hatchery fish produced annually is based on survey data on current stock abundance. Since 1995, annual releases of the state’s combined hatcheries have ranged from 1.4 billion to 1.8 billion juvenile salmon. There are growing concerns among fisheries scientists about whether economic benefits to the industry are outweighed by the impact on wild stocks.
Fisheries researchers like Daniel Schindler of the University of Washington’s School of Aquatic and Fishery Sciences have said their research shows that there’s no question that hatchery pinks and chums compete with wild sockeye for food.
“The evidence is very clear that hatchery fish are competing and interacting with wild Alaska salmon,” Schindler said. “This has been known for well over a decade. Anyone who tells you otherwise is burying their head in the sand.”
“One of the primary reasons that Bristol Bay sockeye are so small right now is competition with hatchery fish,” said the researcher, who does annual boots-on-the-ground salmon studies in Bristol Bay. “There are now more salmon mass in the ocean than probably ever before, and most of that increase is in hatchery chums and pinks.”
Schindler said that to his knowledge, there’s not enough reliable data on marine zooplankton to note any relevant trends in abundance of food for sockeyes in the ocean.
“However, the sockeye growth rates (as reflected in their body sizes) tells the story – there is not enough food out there to produce the body sizes in sockeye that we saw 30 years ago,” he stated.
Juneau-based ADF&G research biologist M. Birch Foster acknowledged that overall, the forecasts and harvests for Chignik and the Alaska Peninsula have been declining the past few years.
“In total, they caught about 230,000 sockeyes in the Chignik management area,” according to Foster, who said that constitutes a poor season. Yet no data shows or suggests that hatchery fish are the cause of the Chignik decline, he said.
“In fact, Chignik did better in 2022 and we expect to increase (harvest) again in 2023,” he added.
State biologists have historically seen decreases—and then increases—in zooplankton populations, and once the abundance of zooplankton, which salmon feed on, falls it can take seven to eight years to come up again, Foster explained.
Schindler, who also studies the Chignik salmon fisheries, said the Chignik fleet has mostly been sitting on the beach since 2018, waiting for openers.
Last year they fished a bit, but it was well below what can be considered “normal,” particularly for sockeyes, he said, adding that while Chignik fisheries have been closed for most of the last five years, they have seen interception fisheries on the South Alaska Peninsula continuing to hammer away.
“Chignik communities are carrying all of the conservation burden,” he commented.
The Alaska Board of Fisheries is expected to take up several dozen proposals, including those related to intercept fisheries on the Alaska Peninsula, Aleutian Island and Chignik fisheries, at its Feb. 20-25 meeting in Anchorage.
ADF&G intends to have its report on solutions to the problems caused by the chum intercept fishery out in early February, in time for public review, fisheries board Executive Director Art Nelson said.