PWS hatchery fish are straying into Kenai Peninsula salmon habitat
The Alaska Department of Fish and Game has been trying to find out if hatchery fish from operations in Tutka Bay Lagoon and Port Graham have been straying into wild fish habitat, and over the past four years, they found that very few of those fish are colonizing wild streams. But scientists found that a number of hatchery fish from Prince William Sound are winding up in streams around Kachemak Bay and Cook Inlet. That trend has left scientists and regulators with more questions than answers.
Alaska Department of Fish and Game Area Management Biologist Glenn Hollowell has been looking into whether pink salmon released from the Tutka Bay Lagoon and Port Graham hatcheries have strayed into other streams, mixing with wild fish.
“Ideally, salmon return to the river or the stream that they were produced by,” Hollowell said. “A corollary to that is salmon should also return to either the hatchery or if they're released at a remote release site, the adults should return to the remote release site that they were imprinted upon.”
Both Tutka Bay Lagoon and Port Graham hatchery operations are run by the Cook Inlet Aquaculture Association, and Hollowell encountered very few of those pinks straying into wild streams. But he also found something unexpected.
“What we found basically beginning from the first year was that we were encountering high levels of pink salmon with thermal marks on their ear bones associated with Prince William Sound hatcheries, which really surprised us,” he said.
Hollowell said that the number of pinks from Prince William Sound straying into salmon systems around the southern Kenai Peninsula varies in each stream every year, ranging from 1 percent up to about 90 percent. A few streams saw a spike in Prince William Sound pinks in 2017.
Fish and Game Principal Geneticist Chris Habicht says stray hatchery fish can pose a problem for wild salmon populations.
“The central impacts of hatchery fish that stray into natural streams are that they can introgress genes from the hatchery into wild populations,” Habicht said. “They can compete for resources within streams. So, there are ecological issues and there are potential genetic issues.”
But Fish and Game isn’t sounding the alarm just yet. Habicht said the most recent report on straying hatchery fish may be misleading.
“It could provide results that are higher than a study that would look at everything,” he said.
The department is conducting a larger study, examining the extent of the straying issue and the impact it may have on wild fish productivity.
Still, this initial data worries opponents of hatcheries. Homer-area resident Nancy Hillstrand has been a vocal opponent of hatchery operations.
“It is very concerning to me because the mandate of the State of Alaska is for a wild Alaskan fish, not for hatchery fish,” she said. “So, if we're mixing these hatchery fish in with our wild fish, all of our little streams were completely inundated with these fish, then we've got real problems here in the Lower Cook Inlet.”
Those hoping quick results will have to wait. Hollowell says Fish and Game’s larger study won’t be complete until 2024.