North Pacific Ocean feeling the heat

Written By Tom Davis

The North Pacific Ocean is cold. Its northern regions are cold beyond what most of us might imagine, and can be violent, unforgiving, and unfamiliar as the surface of the moon. Few, beyond mariners, fishermen, and adventurers challenge its waters.

For centuries, fleets from around the world fished from the far North Pacific. By the 1870’s, sealers roamed the Gulf of Alaska and the Bering Sea in search of the best seal pelts, and for much of the 20th century, abundant halibut stocks drew Canadian commercial fishermen to the same waters. 

One of the richest marine environments in the world, the North Pacific cold zone produces bountiful marine life, ranging from tiny krill to giant halibut. North American and Asian salmon runs – many traveling thousands of miles from their home streams – along with extremely valuable King crab, are among the best known visitors and residents of these feeding grounds. This abundance attracts apex predatory like salmon sharks, porpoises, dolphins, seals, sea lions, orcas, and whales.

The cold zone of the North Pacific Ocean stretches roughly 8,200 kilometers along the 49th parallel from Vancouver Island to southern Japan, and nearly 3,000 kilometers north to the Bering Sea. [Map from]

However, problems are looming. Since the 1980s, water temperatures in the North Pacific have been warming, and until recently, the fishing nations who depend on its resources have been slow to respond.

“The Blob”

Decades ago, Dr. Dick Beamish, a now-retired fisheries biologist, was among the first to theorize the North Pacific Ocean was undergoing a significant shift in temperature. He called the trend a “regime shift,” to differentiate it from the known El Niño warming event and the less damaging La Niña cooling pattern that occur every few years in the Pacific Ocean.

Beamish’s suspicions were confirmed in recent years by longer, more widespread warming events. From the winter of 2013 to late 2017, an expansive warm water plume – nicknamed “the blob” – encompassed vast tracks of the North Pacific Ocean. The blob increased surface water temperatures by two to four degrees Celcius and eventually affected the top 300 metres of the water column. This effected fish species and contributed to the largest Gulf of Alaska common murre die-off in history.

The Blob broke apart in 2018, threatened to return in 2019, then subsided in late winter.

An emeritus scientist with the Pacific Biological Station in Nanaimo, B.C., Beamish began his career in the 1960s.  His extensive scientific research resume includes the Order of Canada in 1998 for identifying sulfur dioxide emissions as the source of acid rain, and the Order of British Columbia in 2004 for his work on fishes that are important to the province.

“We know a lot about salmon, but what we need to know most, we mostly do not know.”

Dick Beamish

His work continued after his retirement in 2011, and in 2019, Beamish organized a multi-national scientific expedition to the North Pacific to test his “fast growth or die” hypothesis. His theory was “ that abundance of salmon is mostly controlled by how fast salmon grow in the early weeks in the coastal ocean, which allows them to accumulate fat/energy needed to survive the winter.”

Even if his hypothesis is incorrect, Beamish noted, it allows scientists to discard it and move on to another line of investigation.

Ocean expeditions

Additional ocean expeditions followed in 2020 and 2022. The latter was a major venture involving scientists from Canada, the U.S., Japan, and Russia using four vessels to conduct research across the width of the North Pacific. This work coincided with the International Year of the Salmon.

The 2022 disposition of winter research work across the North Pacific. [Map from International Year of the Salmon]

Given the Blob’s magnitude and timing there was little surprise when B.C. salmon fisheries collapsed in 2019, followed by a 50 per cent drop in salmon catches by all salmon fishing countries in 2020.

In a lengthy interview, Beamish passed along some findings from his initial research years:

  • A number of Gulf of Alaska salmon were not in good shape and possibly did not survive the winter of 2019.
  • Coho were the second most abundant in catches, which may relate to better Coho returns in recent years.
  • The impact of warmer water on other species is too big a question to answer at this time. However, the collapse of Gulf of Alaska Pacific cod fisheries, beginning in 2018, may be traced to lack of forage for cod, precipitated by warmer water.
  • The unexpected low B.C. catches of chum, pink and sockeye in 2019 and 2020 indicate the value of these surveys in forecasting salmon returns well in advance of fisheries.

The extent of the Blob 2019 event before it dissipated. Blue represents cool water, red is warm water.

[Map courtesy of US National Oceanographic & Atmospheric Administration]

When asked about solutions to the warming trend Beamish said, “We know a lot about salmon, but what we need to know most, we mostly do not know.”

 He qualified this by noting these big-picture research priorities:

  • Discover how salmon adjusted to significant changes in their environments over the preceding thousands of years.
  • Unlock the keys to their adaptability and resilience to change.
  • Decide how to adapt salmon management to these new realities. 

Fellow expedition member Dr. Christoph Deeg is a researcher with the Pacific Salmon Foundation. Deeg said many common coastal pathogens found in out-migrating salmon are absent in the open ocean. He suggested infected fish either died or were able to recover, and that the most abundant pathogens of salmon in the open ocean are transmitted via other marine creatures that make up their food sources.

Where Beamish provided a big-picture view, Deeg described his work as using “tiny clues that provide big insights into the lives of salmon at sea.” Deeg employs genetic tools to investigate pathogens and the stress levels of salmon.

Salmon stressors

Pathogens exist across the ocean environment which, under normal circumstances, do not pose much threat to survival.  However, when other negatives, like warmer water and lack of prey species, are added to the stresses salmon normally face, pathogens can overwhelm weakened immune systems, Deeg said. This stress-induced immune suppression relationship exists throughout nature.

Scientists have been able to track salmon stressors by identifying how specific genes respond to them. The gene indicators show up in tiny samples recovered from their gills using a non-lethal sample recovery process. So far, scientists have been able to monitor ninety-two different genes for stress caused by external factors like water temperature, salinity, oxygen levels, pathogens, and disease, according to Deeg.

Are there solutions to the problems in the North Pacific?

Deeg recommended remedial actions: Halt the loss of critical freshwater and marine habitats; rebuild damaged habitats; employ all proven tools to recover weak salmon runs while maintaining genetic diversity and local adaptations; manage harvest for sustainability; and invest in research.     

Salmon will not become extinct, Deeg said, but we must continue addressing the bigger climate issues.