The Alaska Department of Fish and Game has been conducting a limited study on straying hatchery pink salmon around lower Cook Inlet and Kachemak Bay to see whether fish from the Tutka Bay Lagoon and Port Graham hatcheries have been spawning in wild streams, but to its surprise, it discovered Prince William Sound hatchery fish in several local systems. But hatchery pinks from the Sound are also winding up in the commercial harvest.
Fish and Game began the study in 2014 as Cook Inlet Aquaculture Association was ramping up production in Tutka Bay Lagoon and as its Port Graham Hatchery came online that year.
In 2017, Fish and Game Area Management Biologist Glenn Hollowell sampled pinks from 16 streams around lower Cook Inlet and Kachemak Bay. He found Tutka Bay Lagoon and Port Graham fish in 11 of those systems in mostly low abundances.
A few streams near hatchery returns had higher levels of local hatchery pinks, but Hollowell also found hatchery fish from Prince William Sound to varying degrees around the lower Cook Inlet area.
But as of now, Hollowell has no answer as to why pinks from the Sound are winding up here or just how many there are.
“That’s the big question right now. We don’t have any money to really look at this. The intent of this project was to look at lower Cook Inlet fish that were produced in the hatcheries here and may not have been coming back to the places where we wanted them to,” Hollowell explained. “This project, the intention of it, is not to look at Prince William Sound fish and make any kind of larger statement about what they’re doing. We’re just very surprised that they’re here at all.”
Fish and Game Research Biologist Ted Otis has been working with Hollowell on the project, which also sampled fish from the lower Cook Inlet commercial harvest.
“You want to make sure you’re not intercepting wild stocks in these fairly large fisheries targeting these big hatchery returns,” Otis said.
Otis sampled pinks mostly from commercial fishing boats in Tutka Bay about twice per week over the past three summers, and he recently analyzed the data from the project.
“It looks like it’s right about half, just over 50 percent of the commercial common property harvest was comprised of hatchery fish,” Otis added.
Cook Inlet Aquaculture also harvests fish in order to pay for its hatchery operations. Otis also sampled those pinks, and he said hatchery fish made up 95 percent of the association’s harvest.
According to Fish and Game’s sampling, Prince William Sound hatchery pinks made up about 5 percent of the commercial harvest over the past three years. But Otis explains that it’s hard to translate that percentage into hard numbers of fish.
“We haven’t actually really done that because our sampling design, there aren’t as many samples over as much time period as we’d like to create estimates of how many fish, hatchery fish in this case, are harvested in the fishery,” Otis explained. “We could come up with that number, but I think we want to have a little more directed funding and expand our sampling before you can actually set pretty tight confidence intervals around.”
The same issue stands in the way of extrapolating how many Prince William Sound pinks are spawning in the area.
Otis and Hollowell say they would need to sample more frequently and in more locations in order to get a better idea of how many Prince William Sound fish stray into the lower Cook Inlet area.
Otis said they are searching for funding in order to do so, and Otis notes that he is currently designing a sampling plan in case funding comes through.
Fish and Game has been studying the prevalence and implications of straying hatchery fish in Prince William Sound and in Southeast Alaska, but it doesn’t plan to expand that study to include strays in Cook Inlet. Fish and Game expects to conclude that study in 2023.