The sea’s limit

 

The unprecedented voyage of the R/V Professor Kaganovskiy to probe the resources of the Gulf of Alaska this winter has made one thing clear:

As with the land, so with the sea. There is good pasture. There is middling pasture. And there is bad pasture.

This reality is visually evident in the graphics of zooplankton biomass pulled together by scientists (see above) involved with the International Gulf of Alaska Expedition organized by Canadian Richard Beamish – the grand, old man of Pacific salmon research. 

Beamish, now 78, has spent decades pondering the moving target of carrying capacity for salmon in the Pacific Ocean.

More than 20 years ago, he began warning that scientists know way too little about the environment most important to these fish.

Salmon, he noted in a paper published in the ICES Marine Journal in 1997, “spend most of their life in salt water, during which there is extremely high mortality, it is clear that the ocean habitat must have a powerful influence on abundance. Fishing clearly complicates this basic relationship, but we must not ignore that the underlying relationship still exists.

“Clearly, targets for rebuilding and increasing catch must be based on the productivity of the ecosystem and not on past conditions or perceived historic high abundance levels. Ignoring natural fluctuations in the ocean ecosystem may result in costly and wasteful investments; more importantly, the intervention into a poorly understood process may create problems that are not easily corrected.”

At the time – with Alaska salmon harvests for the first time reaching 200 million – there were concerns a “regime change” in North Pacific sea conditions could bring cooler waters likely to spark a major drop in salmon survival at sea.

And, in fact, salmon catches that had been climbing steadily since the 1980s did slump somewhat in the late 1990s and early 2000s only to come roaring back.

By 2009, Beamish was writing that although there “are different interpretations of the impacts of climate on Pacific salmon…there is also agreement on many issues. One important agreement is that the current abundances of Pacific salmon are at historic high levels of abundance. This indicates that, in general, the recent climate is favorable for Pacific salmon production.

“However, not all species and not all stocks are prospering. The reasons for the high abundance of Pacific salmon and the low abundance of some species and stocks are not well understood.”

The differences in abundance are a big issue in Alaska where low-value pinks now dominate commercial harvests, and where some research has emerged indicating the bounty of pinks could be reducing populations of prized sockeye (red), coho (silver) and Chinook (king) salmon.

“All (Copper River) sockeye salmon stocks examined exhibited a downward trend in productivity with increasing Prince William Sound hatchery pink salmon returns,” scientists studying the Exxon Valdez oil spill discovered 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.”

Though there was an apparent, human-caused reduction in sockeye numbers due to a combination of hatcheries and fisheries management aimed at maximizing the commercial catch of pinks in the Sound, the study noted there appeared to be no long-term reduction in salmon numbers due to the oil spill, a human-caused disaster.

Hatcheries are widely viewed as a good thing in Alaska, even though the consequences of such nature tampering are unstudied and unknown. The state’s chief fisheries researcher dismissed questions about hatchery salmon affects on the environment at a meeting of the state Board of Fisheries by explaining the issue is too complicated to study.

The longest journey

The Kaganovskiy scientists from Canada, Japan, Korea, Russia and the U.S. did, however, took some baby steps toward trying to untangle the puzzle with their work in March and February.

What they found at sea raised more questions than it provided answers although it did serve to underline what a lot of scientists have argued for a long time – that the productivity of the ocean has limits that shift with the seasons, the climate and by area.

Or, in simple terms, the ocean that Alaska’s commercial salmon farmers ranch is just like a ranch. You can only put so many cattle on the pasture before they overgraze the land and begin to starve.

The ocean problem at this time is that no one yet has a clue as to exactly how many salmon the marine pasture can support. The scientists aboard the Kaganovskiy estimated there were but 55 million salmon on the Gulf pasture late this winter.

All of which raised big question number one. Where were the rest of them?

The Alaska Department of Fish and Game has forecast a summer harvest of more than 213 million salmon. About 26 million of those are supposed to be Bristol Bay sockeye, which could have been in the Bering Sea and outside the study area.

But even with the Bay salmon removed from the count, there are 187 million salmon to be accounted for, an estimated 138 million of them pinks.

The Kaganovskiy team estimated only 4.2 million pinks in the Gulf, a tiny fraction of summer’s expected bounty. Speculation is that the fish might have been south of the survey area, which went as far south as the latitude of Puget Sound.

The pinks the survey did find were concentrated in warmer, more southerly waters.

Sockeye, meanwhile, clustered in cooler waters to the north and west of the pinks. There were an estimated 9 million of them, more in keeping with Fish and Game predictions for the year.

After a dismal 2018, the state agency is calling for a return of about that number to north Gulf waters this year. At this point, it also looks like the run could be better than forecast.

The projected Copper River catch of 1.1 million was nearing 800,000 as of Thursday, and the number of fish escaping into the river is now 180,000 over the goal and already near 90 percent of the minimum escapement at a time when managers expect to be reaching 60 percent.

Sockeye are also continuing to swarm the Kenai Peninsula’s Russian River where a mob of anglers attracted by liberalized bag limits appear to be putting only a tiny dent in the number of salmon going upstream.

The river has already topped its maximum escapement goal of 42,000, and fish continue to push through the weir at a rate of 5,000 per day. The Russian is a small, clearwater stream less than 100-feet wide at its widest.

Fish and Game has now upped the limit to nine sockeye per day to try to encourage a higher harvest.

The later-arriving and bigger Kenai River run of sockeye is this year projected to help provide for a commercial harvest of 3 million in Cook Inlet. That would be about three times the catch of last year.

Sockeye in the Gulf in February and March were found to be feeding mainly on krill, which were generally concentrated in the areas where most sockeye were caught. The small, shrimp-like creatures are common prey in oceans around the world. 

The concentration of predatory salmon in areas full of prey was not a surprise, but other things were, starting with that lack of pinks and ranging through an unexpected abundance of coho to the strange mixture of skinny chums and fat chums caught in the same area.

“A surprising difference in fish condition over the study area but even within a single set,” the scientists reported. “The largest difference was observed for chum salmon when fish of both good (robust) and poor (skinny) condition would be captured in a set. DNA analysis will help determine if the variability is due to stock origin.”

Fish that had to travel greater distances to prime feeding grounds or battle currents to get there would be expected to be skinnier than fish that rode in on the current or arrived from nearby.

Scientists are still sorting and further analyzing data they obtained at sea. More is expected to come from that. Beamish, meanwhile, is looking for funding to continue the project in 2020.

He doesn’t expect that to be easy. Basic research funding is hard to find. Almost everyone supports it in theory, but foundations, governments and individuals aren’t rushing to fund it.

Some think its a small miracle Beamish pulled this off once, but the scientists in their summary noted the expedition “can be considered an extremely successful proof of concept that validates the International Year of the Salmon Initiative.”

No Alaska scientists participated in the project, but some state fisheries biologists did contribute to designs of research for gathering data and are participating in some data analysis.