Fish math

 

 

A group of international fisheries scientists is now pointing out the simple, ecological reality of mathematics long ignored by Alaska salmon managers: addition matters as well as subtraction.

With the human-manipulated ecosystem of the North Pacific Ocean once again oscillating wildly, they are warning that fishery management isn’t just about the removals of salmon via human harvests; it is also about the additions of billions of the little fish now dumped into the ocean each year by industrial-scale salmon hatcheries in Alaska, Japan and Russia.

“The intentional release can have wider-ranging consequences than previously thought, as the impacts can propagate through a diversity of ecological interactions,” they warn in a peer-reviewed paper published by Proceedings of the National Academy of Sciences of the United States of America (PNAS) last month.

“This recognition has sparked a discussion of how the massive introduction of native species alters short-term ecosystem dynamics. Yet, current debates overlook the fact that we have rarely assessed the community-wide impact in the long term.”

Evidence to support the theory that dumping billions of hatchery salmon into the Pacific can play havoc with wild ecosystems has been hotly debated for years now, but the researchers reporting in PNAS say they’ve been able to gather the evidence to document long-term, community-wide consequences by studying masu salmon in Japan.

Masu, or cherry salmon as they are sometimes called, are the least common of the six species of Pacific salmon. Their range is limited to northern Japan and the adjacent coast of Asia as far north as Russia’s Kamchatka Peninsula.

Their economic importance is unclear, according to the Wild Salmon Center, because masu harvests are lumped together with pink salmon harvests in Asia.

Economics matter

Economics has long played a role in the global willingness to overlook the consequences of environmental tampering in the form of the billions of young salmon that spill out of hatcheries every year, the authors of the PNAS paper note.

As the scientists from the Salmon and Freshwater Fisheries Research Institute in Hokkaido, Hokkaido University, Japan’s National Institute of Polar Research and the University of North Carolina put it, hatcheries have become “pervasive in natural resource management owing to the significant economic benefit.”

Alaska is the textbook example of economic benefit. The state got into the hatchery business in a big way in the 1970s to prop up the state’s commercial fishing industry as the annual territorial harvests with a long-term average near 100 million fell to 49 million salmon per year in the new state, largely due to cold waters in the Gulf of Alaska.

The goal then was to try to restore harvests to something above 100 million per year, given that Alaska territorial peak harvests had been near that number in the 1940s. The original goal was set at an arbitrary average of 143 million per year with about 36 percent of the catch to be hatchery fish.

The goal was long ago passed.

The state’s five-year, annual average harvest from 2014 through 2018 was over 200 million, and the annual average for the decade of the 2020s was 181 million per year.

Some of the increase came from better management of wild stocks, but much of it has been driven by hatchery production, primarily of pink salmon, the smallest, shortest-lived and least valuable of the species.

When the state witnessed a record harvest of 272 million salmon in 2013, pinks accounted for more than 80 percent of the catch. That year’s take of  219 million pinks more than doubled the annual, average all-species catch of Alaska salmon from the 1940s when all-species harvests were at their previous peak.

Approximately 92 million, or more than 42 percent of the 2013 pinks, were hatchery fish, according to the annual Salmon Fisheries Enhancement Program report from the Alaska Department of Fish and Game. 

The report bragged that Prince William Sound, the big bay at the northeast corner of the Pacific just south of Anchorage, had become an industrial-scale salmon factory thanks to hatcheries.

“An estimated 75 million salmon returned from hatchery releases, accounting for an estimated 79 percent of the total number of salmon in the commercial common property harvest (CPH); 88 percent of the chum, 80 percent of the pink, 45 percent of the sockeye, and 39 percent of the coho salmon in the commercial CPH were hatchery-produced fish,” the report said. “In addition, hatchery-produced salmon contributed an estimated $113 million, or 68 percent, of the ex-vessel value of salmon in that” common property harvest.

“Common property harvest” is the state description for hatchery salmon intercepted by commercial fishermen before they get to the hatcheries. There are also “cost recovery” fisheries at the hatcheries that have turned those facilities, though technically “non-profit” businesses, into operations that provide good-paying jobs in some parts of the state.

The average hatchery employee now earns about twice as much per year as the average commercial fisherman, according to an economic report prepared for the Alaska Seafood Marketing Institute, and the reported $239 million per year in annual hatchery spending now tops the less than $200 million dollars per year (in today’s dollars) the Sound’s commercial fisheries were producing prior to 1981.

Hatcheries were just beginning to kick in that year when Fish and Game reported “the total return of pink salmon was the largest run in recorded history in Prince William Sound and surpassed the previous record set only two years ago by over four million fish.” 

The ’81 vcatch was valued at $58 million, just shy of $200 million when corrected for inflation to 2023 dollars and proved more than four times the size of the 4.5 million catch  five years prior, which had been a record for the 1970s.

Not-so-good old days

Before the state hatchery program began to gear up in the mid-1970s, Sound harvests for averaged 3 million salmon of all species per year from 1951 to 1979, according to a history compiled by fisheries biologists. 

A key part of the harvest during those years was high-value and now world-famous, wild Copper River sockeye salmon of which the annual average catch averaged more than 550,000, or about a fifth of the total harvest, according to state Fish and Game data.

In even number years, when Alaska runs of pink salmon are historically weak, the catches of high-value sockeye sometimes exceeded the catches of low-value pinks in the Sound. The sockeye harvest of 1972 was 17 times larger than the pink catch. Two years later, it was still 61 percent bigger.

But as returns of hatchery pinks increased, the sockeye harvests became a smaller and smaller part of the overall catch.

Wild Copper River sockeye are now a tiny percentage of the overall Sound harvest although their numbers increased in the 1980s and 1990s as the waters of the Gulf of Alaska warmed.  They peaked in the 2010s at about 2 million sockeye per year, according to Fish and Game data. 

The 10-year average for the period 2012 to 2021 is now down to 1.09 million of the fish, and scientists who in the mid-2010s went looking for long-term damage from the Exxon Valdez oil spill that smeared the Sound with crude oil in 1989 found an interesting ecological correlation between wild sockeye and hatchery pinks.

“All sockeye salmon stocks examined exhibited a downward trend in productivity with increasing Prince William Sound hatchery pink salmon returns,” they reported in a peer-reviewed study publised by the Public Library of Science (PLOS) in 2017. “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.

“We do not know if possible deleterious interactions between hatchery pink salmon and wild sockeye salmon in this study are from predation or competition, or whether they occur in nearshore or offshore areas,” the study said. “Pink salmon feeding may cause a general depletion of prey availability that could impact sockeye salmon without tight spatial overlap of these two species. In this regard, the apparent impact to sockeye productivity may reflect a general increase in pink salmon abundance across the northeast Pacific rather than increased abundance of hatchery pink salmon to PWS (Prince William Sound) in particular.”

The 2012 to 2021 average return of hatchery pink salmon topped 38 million per year, according to state data, although it has fallen to near 28.6 million per year over the last five years despite the hatcheries releasing nearly the same numbers of young fish. 

Although hatchery operators try to maximize the chances their fish will survive once they go to sea, ocean survival has generally been declining. The hatchery return of 34 million salmon in 2020 was only 65 percent of the forecast return of 52 million, according to the state reports; a 2019 return of 43 million was 54 percent of the forecast of 79 million.

How these numbers affect wild fish numbers is an unknown, but hatchery fish maximized for a better chance of ocean survival at sea are fish that by definition are supposed to have a competitive advantage over wild fish.

Meanwhile, the interactions at sea between the large numbers of small, short-lived pinks and bigger, longer-lived wild sockeye, coho and Chinook salmon are still not well understood.

Messing with nature

There are correlations between hatchery increases in pinks and declines in these wild fish, but as state fisheries research director Bill Templin pointed out to the Board of Fisheries in 2018, when the board was considering a rollback of hatchery releases, “correlation is not causation.”

That doesn’t make the correlations any less interesting or worthy of serious study.

Under state management since the 1970s, the annual commercial harvest of Chinook – Alaska’s fabled “king salmon,” the largest, longest-lived and most valuable of the species – is now less than half of what it was in the 1970s despite hatchery boosting.

Once famous for producing kings up to near 100 pounds in size, the Kenai River south of the state’s largest city is now closed to fishing for the species and fishing for kings throughout Cook Inlet has been restricted to protect kings because the number of spawners has fallen so low.

Hatchery releases have not been directly tied the decline in the big kings, but Canadian and lower 48 scientists contend that they can document Gulf of Alaska sockeye declines tied to the boom in hatchery pinks.

Three years ago, Brendan Connors of the Insitute of Ocean Sciences with Fisheries and Oceans Canada along with colleagues including Michael Malick from the U.S. National Marine Fisheries Service’s Northwest Fisheries Science Center in Seattle and others revealed they had found “evidence” that from 2005 to 2015, the approximately 82 million adult pink salmon produced annually from hatcheries were estimated to have reduced the productivity of southern sockeye salmon by approximately 15 percent, on average.”

Their study concluding that overabundant hatchery pink salmon are reducing other salmon species via competition for food at sea was published in May 2020 in the peer-reviewed Canadian Journal of Fisheries and Aquatic Sciences.

Among the other scientists involved in the study were Seattle’s Greg Ruggerone and James Irvine from British Columbia who are credited with writing the definitive paper on a North Pacific salmon abundance in 2018. 

That study pegged salmon populations as the highest in recorded history but found the population dominated by pinks. 

Since then, other research has raised questions as to whether hatchery production of chum salmon in Southeast Alaska might be reducing the survival of wild British Columbia chums and possibly replacing wild chums in the Alaska Panhandle. 

The state’s private, officially nonprofit hatcheries primarily run by state-sanctioned associations controlled by commercial fishermen have done a phenomenal job of producing hatchery fish, but the vast majority are pinks and chums or what were once called “dog salmon” in the north.

The dog salmon are now largely marketed as “keta salmon.”

Of the 12.8 million keta caught in Alaska in 2012,  Fish and Game’ Salmon Fisheries Annual Enhancement Report claims 9.4 million – or more than 73 percent were hatchery chums, 

Commercially caught Yukon River chums once supported what little of an economy there was in the economically deprived Interior of Alaska, but hatcheries along the Alaska coast largely gutted that fishery before it went into a still unexplained decline which might, in part, be due to competition for food with the proliferation of the salmon, some of them hatchery fish, in the Bering Sea and western North Pacific. 

Russia now releases about 1.2 billion young salmon, primarily pinks and chums, into the northeastern Pacific each year, somewhat less than the approximately 1.7 billion released by Alaska hatcheries, according to data compiled by the North Pacific Anadromous Fish Commission (NPAFC), a treat organization. 

There has been considerable debate within the scientific community about the ecological consequences of these releases with a variety of scientists arguing hatchery production is detrimental to wild fish and others going even further to argue hatcheries have triggered “trophic cascades” that have at times devastated populations of some seabirds and spread chaos throughout the marine ecosystem.

Lax oversight

Though most environment-affecting activities undertaken in the U.S. now require the completion of an environmental impact statement (EIS) assessing the impacts of anything dumped into the nation’s waters, those National Environmental Protect Act standards have never been applied to the consequences of dumping young salmon in the ocean.

When the U.S. Forest Service conducted an environmental assessment, the baby sister of an EIS, at the Hidden Falls hatchery in Southeast Alaska in 2015, the report outlined how the hatchery’s production of chum salmon had “increased significantly” since the facility was built in 1978-79, but made no attempt to assess how the approximately 45 million young salmon the hatchery was dumping into nearby waters every year affected the nearshore or greater marine environments.

Forest Service reviewers were more interested in the potential problems of increasing numbers of visitors to “a large-scale hatchery that operates in an industrial manner” and stated their preference that going forward the site be managed “as a public education opportunity to tell the story of Forest Service, Alaska Department of Fish and Game, and Nothern Southeast Regional Aquaculture Association cooperative planning for the enhancement of fisheries resources through fish hatchery and aquaculture facilities and activities in the Tongass National Forest.”

The observations are a reflection of how subtle public perceptions affect public policy. There is “good” environmental tampering and “bad” environmental tampering.

Plowing under tens of thousands of acres of wild land in order to transform that land into fields of wheat is, for instance, considered a positive improvement on unproductive nature in the eyes of most. Digging up hundreds of acres to mine copper or other minerals, on the other hand, is largely considered a violent violation of the beauty of nature.

Salmon hatcheries have always fallen into the category of good tampering even as some of those in Alaska have begun to look more and more like the net-pen salmon farms the state banned in 1990.

Alaska hatchery fish are now regularly held in net pens just like the farmed salmon in Norway, Chile and elsewhere. And in those net pens they are fed and excrete waste just like the farmed salmon in Norway, Chile and elsewhere.

“Several factors determine how long the fish are fed in the net pens before they are released,” according to the Prince William Sound Aquaculture Association. “To increase the survival rate, a key target size and release time is selected. But often, critical factors, such as the occurrence of ‘zooplankton blooms’ in the receiving waters, which provide natural feed for the fry upon their release, also influence the decision as to when to release the fry.”

The key target size and release times linked to zooplankton blooms are intended to insure the hatchery fish are bigger than wild fish at release and grow faster than wild fish after release. Both of these factors increase the odds the hatchery fish will survive at sea.

Better odds for the hatchery fish could also translate into worse odds for wild fish, which is what the researchers working with masu samlonsay they found. Or, as they put it in the study, Japanese hatcheries caused “interspecific competition (that) reduced the unenhanced species.”

And in the case of masu, this happened in a situation wherein the hatchery fish were relatively few in number.

“It is noteworthy that the scale of the (masu) release program at the protected watersheds (annual average maximum equals 240,000 fish) is comparable or even smaller when compared with those for other fishery resources,” they wrote. “For example, 649.1 million fish are released annually to supplement the pink salmon stock at the Prince William Sound in Alaska, where wild populations seem to be severely compromised due to competition with hatchery fish.”

Alaska fishery managers and the politically appointed members of the Alaska Board of Fisheries, which is assigned the task of setting state fishery regulations, have, however, refuted that conclusion.

The ocean ecosystem, Templin told the Board, is so complicated it is impossible to document a cause and effect relationship between Alaska’s massive hatchery operations any declines in numbers of wild Alaska salmon, and the Board agreed.