The summer of 2023 brought so many pink salmon to Prince William Sound that commercial fishermen couldn’t catch them all/Facebook

Feral pinks add to hatchery returns

After decades of straying hatchery salmon trying to turn Alaska’s Prince William Sound into one giant salmon farm, a group of Alaska scientists are out with a new study saying it’s a good thing.

Hatchery pinks gone feral upon their return to Alaska have altered the genetics of what was once a fully wild population in th e Sound, says the study published this month in Royal Society Open Science, but the main outcome of hatchery pinks gone wild is a boost to the overall size of the Sound return.

“…In the world’s largest pink salmon fisheries enhancement program,” the study says. “…Hatchery fish presence on spawning grounds…underscore a trade-off between demographic enhancement and preservation of natural population diversity.”

Hatchery fish, the study says, aren’t as productive as wild fish if they elect to avoid the hatchery and spawn naturally in the Sound’s streams and rivers, but what they lack in fecundity they make up for in numbers.

“In our model, while hatchery fish may produce fewer offspring on average than wild fish, their enhanced reproductive contribution offsets the increased competition and phenotypic mismatch costs,” the study says.

The model only appears to confirm what has been obvious in the sound since the 1980s when Alaska began to see the results of a state-funded, hatchery program aimed at farming the sea.

On one level, the program has been a huge success. Alaska’s production of pink salmon – the smallest and least valuable of the Pacific salmon of North America – has skyrocketed as the study notes.

“From 1960 to 1976, before enhancement, Prince William Sound (PWS) produced approximately 6–7 million pink salmon, with harvests of approximately 4 million,” the study says. “In contrast, between 2010 and 2019, harvest rose to approximately 50 million annually, over 80 percent of which was of hatchery-produced salmon. While fisheries are managed to target a high harvest rate of hatchery-origin fish, large numbers of hatchery fish stray to wild spawning grounds, prompting concerns about repercussions for wild populations.”

The collective of scientists from the University of Alaska Fairbanks, the Alaska Department of Fish and Game, the National Oceanic and Atmospheric Administration and Juneau-based Fishheads Technical Service concede their “findings elucidate the potential for long-term demographic and evolutionary consequences arising from specific hatchery-wild interactions, emphasizing the need for management strategies that balance demographic enhancement with the conservation of natural diversity.”

But they said the biggest genetic shift they were able to find at this time was a “variation in adult return timing by up to 20 percent” when the salmon come back from the sea.

Big picture missed

Strangely, though, at a time when the unprecedented abundance of pink salmon in the North Pacific has been suggested as a reason for declines in the numbers of bigger and more valuable species of salmon, the study mentions competition between salmon only in the context of pinks.

“We anticipated hatchery fish presence to reduce wild stock productivity, presuming annual influxes of hatchery strays would intensify competition and induce phenological shift,” the study said. “Contrarily, greater hatchery straying increased population sizes.”

The failure of the study to confront the greater meaning of this increased number of pinks, or even suggest that their numbers might impact other species of salmon, makes the study appear to be more the work of agronomists than fishery biologists and decidedly not that of ecologists.

No one has questioned Alaska’s huge success at the open-ocean farming of pink salmon. And while some questions have been raised about the effects of all the hatchery pinks on wild pinks, those questions were largely muted before the study by a parallel rise in wild pinks, apparenlty due to a warmer ocean.

Some fisheries biologists have even argued that the Sound’s pink explosion of modern times might have happened without hatcheries.

In a peer-reviewed study published in Transactions of the American Fisheries Society in 2000, fisheries biologists Doug Eggers, then at Alaska Fish and Game, and Ray Hillborn from the University of Washington argued that “the evidence suggests that the hatchery program in Prince William Sound replaced rather than augmented wild production.” 

The pink catch then, however, was well short of what it is today.

“Since 1980, the catch has averaged more than 20 million fish per year,” Eggers and Hillborn wrote at the time.

The catch is now more than twice that, according to the new study, despite a 2017 warning from scientists studying the Exxon Valdez oil spill who discovered that sockeye salmon stocks, including the fabled and highly valued Copper River sockeye, “exhibited a downward trend in productivity with increasing PWS hatchery pink salmon returns. While there was considerable variation in sockeye salmon productivity across the low- and mid-range of hatchery returns (0–30 million), productivity was particularly impacted at higher levels of hatchery returns.”

Pound for pound, those sockeye are more than seven times more valuable than pinks, according to state data. Their value led the spill scientists of 2017 to suggest that “competitive interactions in nearshore and offshore environments deserve greater attention in future research in the face of the general increase in the abundance of pink salmon in the North Pacific.”

Instead of pursuing such research, state biologists – thanks in part to funding provided ” by hatchery operators, fish processors, and external grants,” according to the Alaska Fisheries Development Federation – focused their research efforts on studying the “straying” of hatchery pinks.

When the Alaska Board of Fisheries was contemplating limiting hatchery production six years ago and the issue of inter-species competition between salmon came up, Bill Templin, the state’s director of fisheries research, testified that the issue was too complicated to study.

Others, however, have studied it and a group of them last year reported in the peer-reviewed ICES Journal of Marine Science that they had found the fingerprint of pink salmon abundance in the scales of sockeye salmon.

The scales, they said, showed that “peak pink salmon abundances reduced growth of sockeye salmon from seven to 14 percent during the second year in the ocean compared with growth when pink salmon abundance was low, while third-year growth was reduced up to 17 percent.”

They could not calculate how many young salmon failed to survive because of the increased competition for food, but Canadian scientists in 2020 reported that “from 2005 to 2015, the approximately 82 million adult pink salmon (Oncorhynchus gorbuscha) produced annually from hatcheries (alone) were estimated to have reduced the productivity of southern sockeye salmon by 15 percent on average.”

They did not offer a percentage loss of sockeye due to a parallel boom in wild salmon and the hybrid offspring of wild and feral hatchery salmon reported in the latest study.

But it is now clear that the abundance of Alaska pinks has consequences for other species of salmon, and especially struggling runs of sockeyes and chums in Canada and the Lower 48.

“Our findings reveal major declines in the abundance of chum salmon returning to the Central Coast of British Columbia since 1960, with an average decline of more than 90 percent by 2020 across 25 populations with reliable long-term spawner escapement data over the last six decades,” it was reported in the peer-reviewed Canadian Journal of Fisheries and Aquatic Sciences in 2022. 

Alaska wild chums have likewise declined, but the decline has been masked by the production of hatchery chums in the state’s Panhandle.

But none of these losses of wild fish have tempered Alaska’s efforts to farm the sea with pinks, a resilient species now considered “invasive” in Europe and threatening the Atlantic seaboard thanks to straying from old Russian hatcheries in the White Sea, as the Fishing Daily reported in September. 

Tough little fish

What has happened in the Atlantic, along with what the latest study shows is happening in Alaska, would indicate that in a warming world pink salmon do well wherever they stray.

Unfortunately, the same cannot be said for the bigger and more valuable Pacific salmon of North America. Their numbers are in decline just about everywhere but the Bering Sea, and in Alaska the state has fallen far short of its originally promised goals for hatchery production of valuable Chinook, coho, sockeye and chums.

The Chinook hatchery goal of but 300,000 has never been met nor have the sockeye or chum goals. The coho goal has been met but twice. Hatchery pinks, on the other hand, have more than tripled the goal, and that is without an accurate count of how much of a role feral pinks have played in boosting total pink numbers.

The pink harvest last year topped 152 million and accounted for 66 percent of the entire statewide catch, according to the Alaska Department of Fish and Game. 

The only problem was that it wasn’t worth much. The state put the value at $113.7 million.  

In 1988, at the peak of Alaska’s success in the salmon business, a harvest of 65 percent fewer salmon of all species –  99.4 million to be exact –  was valued at $2.1 billion in 2024 dollars. The 49.5 million pinks caught that year comprised about half the statewide, all-species harvest. 

Pinks have, however, dominated harvests in the new millennium, especially in odd-numbered years when the strongest stocks of pinks return. They can prove so bountiful that fisheries biologists have suggested that the odd-year fish put such a dent in the food base of the Pacific that even-year pinks suffer.

The theory is debated, but there is no doubt about the extreme oscillation in pink harvests between even and odd years.

Last year at this time, the statewide harvest of odd-year pinks totaled more than 40 million. The harvest so far this year is just over 6 million, about 5 million of them in the Sound where last years’s harvest at this time was already close to 24 million.

The season is still early for pinks, but last week’s statewide harvest, which should have going up, went down. And the harvest is badly lagging the even-year catch of 2022 when nearly 26 million pinks had been caught statewide by this time.

The pre-season forecast was for a harvest of 69 million pinks. In a normal year, a third or more of that harvest would have been expected by now.

Fish and Game’s statewide summary of fishing activity for the week ending July 19 reported that in the Sound pink and chum “observations and stream escapement indices have improved in some areas but remain below what is expected for this timeframe.”

Meanwhile, the fishing was not going well at the Solomon Gulch Hatchery where the state reported that the “overall cumulative purse seine harvest of pink salmon – including (hatchery) cost recovery – through July 18 is 2.81 million fish. This compares to an even-year average (2000-2022) of 10.23 million fish for the same date.”

To the west along the Alaska Peninsula, the report said, the “pink salmon harvest of 311,956 fish is below the recent 10-year average of 2,713,521 fish and the most recent even 5-year average of 1,367,309 fish.”

It could be the humpies, as many Alaskans call pink salmon, are simply late this year, but there are early-season hints of the great bust of 2020 when the harvest of Pacific salmon saw its biggest ever year-to-year decline.

After that season ended, Seattle-based fisheries consultant Greg Ruggerone and colleagues James Irvine and Brendan Connors with Fisheries and Oceans Canada told the North Pacific Anadromous Fish Commission, a treaty organization, that “we hypothesize that a tipping point was reached in the North Pacific Ocean, leading to the substantial decline of all five species of Pacific salmon in 2020.

“We infer that the tipping point was caused by the combined effects of unusually frequent marine heatwaves since 2014 and exceptional back-to-back year abundances of pink salmon in 2018/2019.”

The good news this year is that the Bristol Bay harvest of sockeye salmon of about 30 million is above the preseason harvest forecast of 26 million, but the bad news there is that the 2024 sockeye are the smallest ever. 

Bay sockeye were expected to make up about 20 percent of the 2024 years harvest with more than 50 percent coming from humpies with chums expected to make up the rest of the harvest.

Returns of both the latter are lagging, but it is early.