Ford Arm salmon dead of hypoxia/Amy Hemenway photo

Hatchery salmon smothering wild salmon?

Scientists studying warming in Alaska’s Tongass National Forest have stumbled on a new way in which the state’s massive aquaculture industry could be harming wild salmon: hypoxia.

This particular problem with a lack of oxygen in the waters of some streams in the coastal rainforest during dry years has long been known. Reports of warm weather die-offs of salmon in the state’s Panhandle region date back to the early 20th century.

But the problem has been growing in recent years, and the study just published in the peer-reviewed Science of the Total Environment notes the confluence of regional warming and untold numbers of straying hatchery fish entering Southeast Alaska streams. 

“High densities of spawning Pacific salmon (are) consuming oxygen faster than can be replaced by reaeration,” the study says. “This process may be exacerbated when salmon densities are artificially inflated, such as when hatchery-origin salmon stray into rivers instead of returning to hatcheries.”

Alaska Department of Fish and Game biologists working in the region long ago noticed the problem of straying hatchery chum and pink salmon, the smallest of the Pacific salmon species, sometimes clogging creeks and rivers near hatcheries.

At Ford Arm Creek on Chichagof Island where the state maintained a fish counting weir from 1980 to 2009 as part of a long-running, coho salmon study, one of them recalled that when the creek became stuffed with salmon “the fish response was somewhat reminiscent of a theater fire.

“Everything would seem fine one minute, and then there was a panicked rush upstream and fish would start rolling over. Typically, every single larger salmon downstream of the weir (coho, chum, sockeye) would end up dead, but often only around 30 to  40 percent of pinks, which seem more resistant. In (a) 1995 event, the crew counted 816 dead adult cohos (zero live) between the weir and saltwater.”

These events not only killed adult salmon but younger fish rearing in the stream as well.

Killing the old and the young/Amy Hemenway photo

Broad implications

The latest study conducted by researchers from the University of Alaska, the U.S. Forest Service, the U.S. Geological Survey and the Southeast Watershed Coalition suggests this problem might be a lot bigger than the die-offs in Ford Arm Creek.

“In Southeast Alaska, hatchery salmon production has increased rapidly since the 1970s, with over 553 million chum salmon and 64 million pink salmon released in 2021 alone,” they wrote. Straying is pervasive in streams with outlets less than 25 kilometers (16 miles) from nearshore marine hatchery release sites,” they wrote.

After modeling the consequences of salmon missing the hatchery on the return from the sea and instead trying to spawn in regional streams, they reported, “our model predicted that low-gradient stream reaches, regardless of water temperature, are the most prone to hypoxia due to low reaeration rates. Our spatial analysis determined that nearly 17,000 kilometers (slightly more than 10,500 miles) of anadromous-accessible stream reaches are vulnerable to high densities of hatchery-origin salmon based on 2021 release sites.”

The problem is self-correcting in a natural system. Hypoxic events reduce spawning and survival, fewer fish return in future years and the issue is resolved. This is not the case if returns are being boosted by straying hatchery fish.

Then instead of hypoxia-related problems scaling down, they could continue to scale up, leading to a steady decrease in watershed productivity.

And Alaska has a lot of straying hatchery salmon, given that it is a world leader in farming salmon on the high seas – something the state’s commercial fishermen and salmon processors prefer to call salmon “ranching” in line with the vision of the state’s commercial fishermen as the last American cowboys.

Alaska’s hatcheries turned the U.S. into the world’s biggest player in farming the sea as opposed to limiting salmon rearing to net pens – as in Norway, Chile and many other countries – or moving salmon farming on land as has been pioneered in the U.S. Midwest and elsewhere, and is now ramping up in a big way in Japan.

Alaska banned net-pen farming in 1990, thinking it could control the global market for salmon with wild salmon stocks rebounding from record lows in the early 1970s and a massive state-backed hatchery program born of the salmon shortage of the ’70s starting to crank out fish by the tens of millions.

By 1983, the Alaska Department of Fish and Game was promising production of 51 million hatchery fish per year from a catch to comprise “25 million chum, 8 million sockeye, 1.5 million coho, and 300,000 Chinook salmon; the remainder will be made up of pink salmon.”

The sockeye, coho and Chinook goals have never been met. Overall catches of Chinook and coho – the combination of wild and natural salmon harvests – have actually declined since 1983, but production of pinks, the cheapest of the salmon to raise in hatcheries, has exploded.

The humpy boom

The Alaska salmon fisheries enhancement annual report 2021 documented a harvest wherein pinks, or humpies as Alaskans commonly call them, made up 83 percent of the year’s catch of almost 69 million hatchery fish.

Averaging three pounds in weight, humpies are pound-for-pound the least valuable of Alaska’s five species of salmon. Historically, they all went into cans.

Some of the larger pinks are now fileted with the filets sold at budget prices designed to undercut the price of larger farmed salmon filets. But many are still canned while increasing numbers are destined to become pet food or fish meal that can be made into fertilizer or used to feed other animals or fish.

Humpies were worth 37 cents per pound on average to Alaska commercial fishermen in 2021, according to state records, about a sixteenth the value of a Chinook at an average dock price of $5.82 per pound and about a quarter the value of a coho at an average per pound price of $1.45.

Chinook and coho are unfortunately costly to produce, however, and for that reason Alaska hatcheries raise few of them. The 2021 harvest of hatcher Chinooks was reported to be 68,667 fish and the coho harvest, 799,630.

For most of the approximately 13,000 commercial fishermen permitted to operate in Alaska, the hatchery program has produced little or no benefit, but for the approximately 1,200 issued purse seine permits when the state created a limited-entry program for its fisheries in the 1970s the hatchery program has been a big success.

Economists examining the state’s commercial fisheries in 2016 reported that success has also transformed some state fisheries.

“Shifts in terrestrial agriculture from a diverse mix of low- and high-value crops to focusing on high-volume, low-value crops (such as soybeans or cereals) may have parallels for Alaskan salmon fisheries,” they wrote, “particularly those fisheries that have more recently targeted low-value species with less diverse life history characteristics (such as pink salmon).”

Along with this shift to low-value, high-volume species has come another change common to U.S. terrestrial agriculture: government supports.

“Over the course of our study 1975 to 2016, salmon fishery disasters were declared in Alaska in 1997 to 2000, 2009 to 2012 and 2016, totaling more than $100 million dollars,” the study reported. “As some of these salmon fisheries have become more specialized, management may benefit from future work into how specialization affects the likelihood of disasters occurring, as well as how disaster funding affects the participation and revenue of individual fishers.”

Farm subsidies have long been a controversial subject both nationally and internationally, but those in Alaska have gone largely unnoticed to date.

Rousing success

And purely on the production front, the Alaska hatchery program has been hugely successful in its prime goal of producing more fish for commercial fishermen.

In 1975, as this new Alaska business was just hatching, the U.S. was dumping a mere 220 million young salmon in the Pacific Ocean with 98 percent of those fish originating from hatcheries in Idaho, Oregon and Washington, according to the data compiled by the North Pacific Anadromous Fish Commission (NPAFC).

By 2022, according to the NPAFC, U.S. releases were approaching 2.2 billion – a tenfold increase – with about 87 percent of the hatchery fish coming from Alaska ranches.

The U.S. now releases more hatchery salmon than Japan, which pioneered open-ocean farming. And Alaska alone releases almost as many hatchery salmon as the Asian Island.

Japan largely abandoned its wild salmon stocks decades ago in favor of producing salmon with hatcheries. Wild salmon have survived in Japan – salmon being an amazingly resilient species – but the populations are small.

“Although past management of Japanese chum salmon focused on producing and releasing hatchery-reared fish, Japanese salmon scientists and hatchery managers have become aware of the importance of conserving wild fish,” Japanese researchers reported in 2014. “Counting surveys of wild fish recently conducted in Hokkaido have found that natural spawning occurs in many rivers. However, the majority of chum salmon returning to Hokkaido are hatchery-released fish; therefore, the ecological sustainability of the chum salmon stock is controversial.” 

The search for wild fish found that in “the total of approximately 1,500 rivers in Hokkaido…naturally spawning chum salmon, chum salmon ascended at least 191 and 175 rivers in Hokkaido in 2008 and 2009.”

Whether any of those fish were truly wild is an unknown given almost all, if not all, Japanese streams have been affected by either stocking of hatchery salmon or straying of hatchery salmon.

“It is possible that the spawning fish seen in our study included hatchery-origin fish that strayed into non-natal rivers because intensive hatchery programs are conducted throughout Hokkaido,” the Japanese researchers admitted.

The numbers of natural spawners were also tiny with the total escapement estimated at less than 21,000 fish. That’s smaller than a third of this year’s return of the first run of wild salmon to the 49th state’s popular Russian River on the Kenai Peninsula. 

Statewide, the number of naturally spawning salmon in Alaska rivers still reaches tens of millions every year.

Alaska has been far more aggressive than Japan in trying to protect its wild salmon while gearing up a massive hatchery program, but current-day chum harvests in the Panhandle raise questions about a Japan-style shift in that fishery.

Watershed Watch Salmon Society graphic

A fading boom

Southeast salmon hatcheries in the 1990s drove an explosion in chum production that allowed commercial fishermen there to takeover markets for so-called “keta salmon” once dominated by Yukon River fishermen who caught wild chums.

The wild chum fishery on the Yukon collapsed as a result. It has since withered due to a catastrophic decline in returns yet to be fully explained although competition with Japanese and Russian hatchery fish in the Bering Sea and western North Pacific has been suggested as part of the problem.

Meanwhile, the number of Southeast chums being harvested has started to slip since peaking at the start of the new millennium. The harvest has also become ever more dependent on hatchery fish.ann

“The annual commercial harvest of chum Salmon in Southeast Alaska the past 20 years averaged 8.4 million hatchery-origin fish and 10.2 million total fish,” U.S. scientists reported in a peer-reviewed study published in 2021 in the North American Journal of Fisheries Management.

That average annual harvest of 1.8 million wild chums reported there is 40 percent of the 50-year average of harvest 4.5 million wild chums in the region, and the 20-year average somewhat misrepresents the situation as it exists today.

The average wild harvest from 2009 to 2018 was but 900,000 or but 20 percent of the long-term average harvest of wild chums.

A hatchery rescue?

This could be a good thing if the decline in wild fish is wholly natural and the hatcheries are picking up the slack to keep commercial fishermen in business.

But it could be a bad thing if the hatcheries are doing little but replacing wild fish produced for free with costly-to-produce wild fish while, at the same time, depressing wild returns.

To increase the survival of hatchery chums, Southeast salmon farmers are now fattening the fish in saltwater in net pens – the same sort of net pens used by the farmers in Norway – for two to three months. 

Pen-rearing requires costly feed but is thought to give the hatchery fish a competitive edge at sea that increases marine survival, ensuring more fish return to the hatchery.

A competitive edge, however, could help hatchery fish squeeze out some wild fish in the battle for survival. Southeast commercial fishermen don’t seem to care. They are businessmen, and at the end of the day, it doesn’t really matter to them if they’re catching wild fish or hatchery fish, which they market as wild-caught salmon, as long as they’re making money.

Canadian fishermen, who’ve long been frustrated by the number of Canadian-origin salmon intercepted in the commercial fisheries of the Panhandle, have, however, started to take notice of what is going on, and for good reason.

“Overall, (Pacific) salmon catches increased between the 1970s and 2010s – Russia’s total catch increased by 4.9 times, and the U.S. catch, mostly in Alaska, went up 2.6 times,” Jude Isabella reported in Canada’s Haiku magazine May 2022. “In Japan and British Columbia, catches decreased, whether fishers were harvesting wild or hatchery salmon.”

In Japan, where almost all the harvest was hatchery fish, the decline was relatively small, but “the Canadian catch from 2019 to 2021 looks to be only 6.1 percent of the 1970s average,” Isabella reported.

Most scientists believe a warmer North Pacific Ocean friendlier to salmon at the northern end of their range than at the southern end has played a significant role in the decline in returns of salmon to both Canada and the Pacific Northwest.

But some have also questioned whether hatchery boosting of salmon numbers, especially of pinks and chums, has further aggravated the situation.

“Are There Too Many Salmon in the North Pacific Ocean?” salmon scientists Greg Ruggerone, James Irvine and Brendan Connors asked in the NPAFC’s January 2022 newsletter, wherein they noted a Pacific takeover by pink salmon.

“Overall, pink salmon represented approximately 74 percent of total salmon abundance in 2018/2019,” they wrote there. “Most pink salmon are of natural origin, but abundance of hatchery pink salmon during 2005 to 2015 was greater than abundance of wild chum salmon and approximately equal to abundance of wild sockeye salmon.

“Total chum and sockeye salmon represented only 14 percent and 12 percent, respectively, of total salmon abundance in 2018/2019. These values exclude Chinook and coho salmon, whose combined reported commercial catch  was 1.5 percent of total salmon catch from the North Pacific during 2018/2019 and approximately 5 percent of total salmon catch, on average, during 1925 to 2020.”

They went on to warn of the possibility that regional self-interests now pose a threat to wild salmon.

“It is not surprising that fishery managers are primarily concerned with maintaining those populations that return to regions they manage with little consideration for how these populations might adversely affect other salmon,” they wrote. “Likewise, hatchery managers release large numbers of juvenile salmon to maximize harvests in nearby salmon fisheries, often with little consideration for, or understanding of, potential competition It is not surprising that fishery managers
are primarily concerned with maintaining those
populations that return to regions they manage with
little consideration for how these populations might
adversely affect other salmon. Likewise, hatchery
managers release large numbers of juvenile salmon
to maximize harvests in nearby salmon fisheries,
often with little consideration for, or understanding
of, potential competition effects on other distant
salmon populations that compete for the same
common pool of resources at sea.”

The new study on hypoxia in Southeast raises questions not just as to the “effects on other distant salmon populations that compete for the same common pool of resources at sea” but as to the effects on salmon close to home.

This is especially so given that hypoxic conditions do not just kill adults but can reduce overall productivity in salmon streams.