Deadly little fish



A schematic of how salmon in Alaska influence shearwaters in Australia. The dark lines are shearwater migration routes. The yellow circles the range of pink salmon from Japan and Russia, the red the range of Alaska salmon/National Academy of Sciences

With a growing number of Alaskans pushing the state Board of Fisheries to take a closer look at 49th state salmon ranching, scientists from the University of Alaska Fairbanks and Australia have joined other scientists warning of the ecosystem consequences of hatcheries dumping billions of hungry young fish in the North Pacific each year.

Alan Springer and his colleagues contend seabirds are starving in unusually large numbers because the salmon, especially pinks, consume too much of the food that would normally support the birds. 

What they discovered, as reported in a peer-reviewed study published online  Monday at the website of the Proceedings of the National Academy of Sciences of the United States of America on Monday, is “another example in a growing list of ecosystem disservices of an abundant species of North Pacific salmon and the need to include ecosystem processes at such geographic scales in conservation and management considerations for this northern open ocean.”

“Pink salmon in the North Pacific Ocean have flourished since the 1970s with growth in wild populations augmented by rising hatchery production,” they wrote. “As their abundance has grown, so too has evidence that they are having important effects on other species and on ocean ecosystems.”

Fisheries biologists Greg Ruggerone from Seattle and Jim Irvine from British Columbia, Canada, in April published a peer-reviewed study theorizing that declines in the number and size of Alaska Chinook salmon – the big “kings” for which the Alaska is famous – are also tied to hatchery salmon overwhelming an ecological niche shared with other salmon and seabirds.

“In Alaska, declines in size at age and abundance of Chinook salmon and coho salmon and a decrease in age at maturation in Chinook salmon may be related to the alteration of the food web by highly abundant pink salmon and higher mortality during late marine life,” they wrote.

Springer and nine co-authors, most of them Australians, now contend the ecological implications of stuffing the ocean with pinks reach far beyond Alaska.

They paint a picture of consequences from a Prince William Sound salmon spill that could over the long term dwarf the damage of the infamous Exxon Valdez oil spill of 1989. Approximately 250,000 seabirds perished in the oil spill, scientists eventually concluded. 

Annual kills

The bird biologists have fingered pink salmon as the villains in the death of what could be tens of thousands of short-tailed shearwaters per year for decades, a problem that could only get worse as hatchery production continues to increase.

“….Beginning in 2007 and coinciding with the increasing abundance of odd-year pink salmon, wrecks occurred in every odd year to at least 2013,” they wrote. “Wrecks” are the descriptive term for massive die-offs of shearwaters. The phenomenon has been regularly observed since the 1800s, but has accelerated in recent years.

“The wreck in 2013 was extreme, when very high numbers of birds were stranded in Australia and Tasmania, and even in New Zealand, where they do not nest , and corresponded with extremely high abundances of pink salmon returning to United States waters,” they wrote.

“Birds in those wrecks…were emaciated, suggesting that they failed to accumulate sufficient fat before departure on their southward migration to sustain them until they could refuel upon their return.”

Short-tailed shearwaters summer in the North Pacific Ocean and the Bering Sea where they compete with young salmon for food.

“Diets of pink salmon and short-tailed shearwaters overlap, and the biennial pattern in shearwater body condition has been linked to competition with pink salmon for common prey,” the scientists wrote.

They noted the overall abundance of pinks sharing shearwater habitat stayed within a “comparatively small, low range from the early 1950s to the mid-1970s, then increased markedly through about 1990.”

Alaska hatcheries went from producing about 20,000 salmon per year in 1975 to producing 27 to 54 million salmon per year by the 1990s, according a 2007 review of  “Alaska’s salmon hatchery ocean ranching program.”

Alaska banned salmon farming in 1990 in the hopes of limiting competition for salmon in the market place, but it went all in on private, nonprofit hatcheries owned by commercial fishermen and financed with state loans.

The big pink increase in the 1990s “was followed by a second period of relative stability to about 2004,” according to Springer and his colleagues. “Beginning in 2005, odd-year stocks increased substantially, whereas even-year stocks remained about the same as in the previous interval. The odd-year mean in 2005–2015 increased by 35 percent over the odd-year mean for 1990–2004.”

Pink salmon spend only a year at sea but have such an impact on the marine ecosystem that it is believed one generation of pinks can suppress the next generation.

“Possible mechanisms are cannibalism, disease transmission, food depletion and habitat degradation by which one lineage affects the other, although no mechanism has been well-studied,” Martin Krkošek and colleagues reported in Proceedings of the Royal Society Biological Sciences in 2010. 

Springer and colleagues note the peak years for pink salmon abundance correlate with the big shearwater wrecks, and the shearwater die offs have been getting worse as hatchery production has boomed in the new millennium.

Having seen the success of Alaska hatcheries, Russia nearly doubled its production of hatchery salmon from 2000 to 2010. 

Global implications

Springer and colleagues argue all the hatchery fish being pumped out by Japanese hatcheries dating back to the 1970s and the newer hatcheries in Russian and Alaska are having global implications:

A pink salmon fry released in Prince William Sound rides the Alaska coastal current  west to the Bering Sea to eat the food that would normally nourish a shearwater that leaves for its wintering and breeding grounds in Australia only to die of starvation.

The scientists describe this as a macrosystem in which pink salmon alter ecological interactions at the “local, regional, basin, hemispheric, and transhemispheric” levels.

“The desire to continue to raise production levels of wild and hatchery salmon is understandable,” they concede. “The overall annual multinational economic value of Pacific salmon is in the order of $1 billion US, and the industry employs tens of thousands of people. But it is now time to take stock of the consequences—the ecosystem
disservices of salmon—of doing so on other economic, social, cultural, and ecological values in the North Pacific/Bering Sea and, because of the teleconnection described here, in the South Pacific/Tasman Sea as well.”

Whether anyone cares about the ecosystems consequences of this sort of environmental tampering only time will tell. The short-tailed shearwater is a brown, nondescript, gull-like bird common to the Pacific Ocean.

Even the scientists admit, “the short-tailed shearwater is not a species in peril.

“But,” they add, “the apparent response of these birds, as well as responses of humans, resident North Pacific/Bering Sea seabirds, other salmon, herring, and likely species yet to be identified, to ecological forcing by pink salmon suggests that pink salmon are altering the distribution of wealth stored in this macrosystem. Together, these responses emphasize that we must develop a deeper conservation conscientiousness for this entire oceanic system and more informed approaches for the management of the whole.”


That altruistic view runs up against powerful economic influences and, at least in Alaska, a lot of skepticism. Even some Alaska commercial salmon fishermen dependent on salmon species that might be losing out to hatchery pinks appear reluctant to accept the idea that the salmon produced by other Alaska fishermen could be altering the environment.

Dumping more and more hatchery salmon into the ocean has always been viewed as a good thing in Alaska, so how could it possibly be bad?









9 replies »

  1. Hogwash!
    Oh and by the way, how did that BOF emergency petition work out for you? Have not heard a report from you, since mtg on the 14th.
    Whiners and doomsayers, get a grip! The sky is not falling!

  2. Here is another one on birds and pink salmon this one clearly shows the need for the odd even year of the pink salmon cycling phenomenon. Hatchery production attempts to flatten this cycling odd/even year design of the ecosystem to serve as a predictable marketing strategy…This business plan is at the detriment and demise of many other species. Species need the relief and release from this voracious invasive pink salmon predator biomass… Who would have thought? But as this paper states they grow 500% of their body weight in the last 4 months of their life..eating.
    Lets see… 100,000,000 pinks at 3.1 pound average return in 2015…equals 300,000,000 pounds of predator biomass eating 2.5% of their body weight equals 7,500,000 pounds of seafood eaten per day.? 225,000,000 pounds in a month? No it can’t be… can it?

  3. No way. A peer-reviewed study that claims pink salmon disrupt the food cycle and cause bird starvation!? Not possible according to self-proclaimed expert Bill Yankee. Dr. Yankee told me, via a previous post on this site, that pinks could not possibly be involved with the PWS murre die-off. Now these silly scientists are claiming another species of birds are being impacted by pinks!? The nerve of them to publish such rubbish without consulting Dr. Yankee!

    • OK James, your thing about Common Murres was a one-time situation that doesn’t make sense since pinks have been released for 30 plus years. This situation with Shearwaters is ongoing-entirely different things.
      And another thing that’s different with these two species of birds is that Murres can dive up to 300 ft after their prey while Shearwaters get their feed at the surface, commonly by creating a bees nest type behavior that tends to bring krill to the surface where shearwaters and gulls feed. I was told by a biologist (observer on my boat in the Gulf) that the more birds swarming the more it attracted the krill from the deep.
      Anyway, my observation in early ninetys was these swarms of shearwaters and gulls of many kinds were common from SE to Cape St. Elias. Then later when I started running my boat back and forth between Juneau and Cordova I never observed that behavior again and that was until about 2010 both Spring and Summer. It’s my opinion that those birds (shearwaters) could very easily have been impacted by a surface feed problem (could be large numbers of pink salmon).

  4. You’re building a case, Craig. Keep it up.

    William Ruckleshaus banned DDT in 1972 on less data than this.

    It is a political problem that needs a political solution. Perhaps the next governor will be so inclined.

    Still think fish farming PWS for pink salmon would make a great test case – a pilot, if you will – for repeal of the statewide ban on fish farming. Cheers –

  5. “In Alaska, declines in size at age and abundance of Chinook salmon and coho salmon and a decrease in age at maturation in Chinook salmon may be related to the alteration of the food web by highly abundant pink salmon and higher mortality during late marine life,” and the crux here IMO is the small word “may” be related to etc., etc.
    I just don’t have the knowledge to be able to come up with the study that could change that word “may” to “is.” This is a biological conundrum that will take time to study and determine whether/not the theory is true. My money would be on tackling this problem from a different angle.
    In the meantime, my position is that we know that “straying” is occurring and I believe that we also know that “straying” causes harm (and perhaps even destruction) of wild fish of the same species. Most of the arguments here are relative to pinks but in my opinion the same straying is occurring with chums and I’ve witnessed the harm done to the wild chum runs in all of College Fiord of PWS. Further, its also my belief that this harm done to wild fish is not allowed.
    That said, how does one go about showing that this harm is contrary to our F & G laws? That’s for the legal eagles to do IMO.
    Very interesting look @ shearwaters. At one time, I believe, shearwaters were the most abundant birds in the world. That may be changing.

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