Warmer Pacific waters, other factors may be harming marine life
MARK HUME, VANCOUVER — The Globe and Mail, Mar. 18 2015
Record-high sea-surface temperatures in the Gulf of Alaska and die-offs of sea lions and seabirds on the West Coast are raising concerns about changing conditions in the Pacific.
A report released this week by the U.S. National Oceanic and Atmospheric Administration (NOAA) says a massive “warm blob” of water that is up to 3 C higher than average is spreading south from Alaska. That, together with other environmental factors, could make the ocean less productive for many species, including salmon.
The changes are occurring in addition to an El Nino event that developed in the Pacific this winter, and which brought warmer water north from the equatorial Pacific. The warm waters in Alaska developed about one year ago.
“We are seeing unprecedented changes in the environment,” Toby Garfield, director of the environmental research division at the U.S. Southwest Fisheries Science Center said in a statement.
The report states that, in addition to higher sea-surface temperatures, there have also been weaker upwellings of cold currents. Those upwellings bring nutrients up from deeper ocean levels, enriching the base of the marine food web.
The NOAA report states that last summer and fall, the weights of California sea lion pups were below average in some rookeries, and many pups died, apparently from starvation.
“That trend has continued into winter, along with strandings of dead pups. It is possible that another UME [unusual mortality event] will be declared soon in 2015,” the report states.
The NOAA report also says that Cassin’s auklets, especially juveniles, have been dying in large numbers.
“Many dead auklets appear emaciated. Cassin’s auklets prey on zooplankton, and this die-off may be a leading indication of suboptimal feeding conditions,” the report states.
Dr. David Bradley, B.C. program manager of Bird Studies Canada, said Wednesday there is “definitely a spike in [marine bird] casualties in B.C. this winter.”
But he said “it’s a big mystery” as to why the birds have been dying and he is waiting to see whether U.S. researchers can confirm a correlation between marine-bird deaths and warmer sea-surface temperatures.
Dr. Richard Beamish, an emeritus scientist with the Department of Fisheries and Oceans, said the NOAA study suggests a significant shift of oceanic conditions is taking place.
“Some of us, me in particular, believe there are these major climate, ocean events which we’ve been calling regimes,” he said. “We had a major regime shift in ’77 and then in ’89, probably another around 1998 … and since they [are] occurring roughly every 10 years … most of us have been expecting we’d see a change.”
Dr. Beamish said regime shifts can have a dramatic impact on salmon production, causing stocks to crash.
But some fish species thrive under warmer conditions, and fish rarely seen off the West Coast can become plentiful.
“We could have a bizarre season, perhaps with tuna up as far as Alaska,” he said.
Aaron Hill, executive director of Watershed Watch Salmon Society, said the changes are worrying.
“It’s certainly concerning, because there are a number of factors in addition to this that are conspiring against B.C. salmon populations,” he said, noting low snowpacks this winter will lead to reduced river levels. “If we get another hot summer on top of that, it will be really bad [for spawning salmon].”
Mr. Hill urged government to restrict commercial catch levels this year.
“I’d like to see [Fisheries and Oceans] take a more precautionary approach to salmon populations under these conditions,” he said. “They are basing management decisions on the assumption we have a certain level of productivity in our salmon populations. But with these environmental conditions right now, that seems like a brash assumption.”
Reference Links:
West Coast waters shifting to lower-productivity regime, NOAA report finds
NOAA, Northwest Fisheries Science Centre, March 17, 2013
West Coast waters shifting to lower-productivity regime, new NOAA report finds
State of the California Current report highlights record-warm conditions and effect on fisheries
NOAA Fisheries West Coast Region, March 17, 2015
Large-scale climate patterns that affect the Pacific Ocean indicate that waters off the West Coast have shifted toward warmer, less productive conditions that may affect marine species from seabirds to salmon, according to the 2015 State of the California Current Report delivered to the Pacific Fishery Management Council.
The report by NOAA Fisheries' Northwest Fisheries Science Center and Southwest Fisheries Science Center assesses productivity in the California Current from Washington south to California. The report examines environmental, biological and socio-economic indicators including commercial fisheries and community health.
"We are seeing unprecedented changes in the environment," Toby Garfield, Director of the Environmental Research Division at the SWFSC, told the Council when presenting the report, citing unusually high coastal water and air temperatures over the last year. Climate and ecological indicators are "pointing toward lower primary productivity" off California, Oregon and Washington, he said.
That could translate into less food for salmon and other marine species, added Chris Harvey of the Northwest Fisheries Science Center. High mortality of sea lion pups in Southern California and seabirds on the Oregon and Washington coasts in recent months may be early signs of the shift.
Among the highlights of the new State of the California Current Report:
- Record-high sea surface temperatures combined with shifts in the Pacific Decadal Oscillation, North Pacific Gyre Oscillation and weaker upwelling of deep, cold waters indicate declining productivity in the California Current.
- After several productive years the biomass of tiny energy-rich organisms called copepods, which support the base of the West Coast food chain and provide important food for salmon, has declined significantly.
- California sea lion pups and seabirds called Cassin's auklets found dying and emaciated in large numbers in recent months may reflect the transition to less productive marine conditions.
- Although commercial fishery landings have remained high in recent years, the fishing fleet has become more specialized in terms of targeting specific fisheries. That may expose the vessels to more fluctuations of catch and revenue if those fisheries decline.
"This year's report is very useful," said Council Chair Dorothy Lowman. "We're looking forward to working with the science centers to find ways to integrate this information into management."
Scientists produced the report as part of NOAA's Integrated Ecosystem Assessment Program, which tracks conditions across coastal ecosystems to provide insight into environmental and human trends and support decisions on fisheries and other activities. The California Current Ecosystem is one of seven U.S. ecosystems monitored by the program.
"We're seeing some major environmental shifts taking place that could affect the ecosystem for years to come," said John Stein, Director of the Northwest Fisheries Science Center. "We need to understand and consider their implications across the ecosystem, which includes communities and people."
In recent years the California Current Ecosystem enjoyed highly productive conditions, with strong upwelling of deep waters from the north flush with energy-rich copepods that supported high salmon returns and high densities of juvenile rockfish, sanddabs and market squid. In 2014 waters off Southern California and in the Gulf of Alaska turned unusually warm, and these so-called warm "blobs" have since grown and merged to encompass most of the West Coast.
The coastal warming includes an influx of warmer southern and offshore waters with leaner subtropical copepods that contain far less energy and are often associated with low productivity and weaker salmon returns. Overall the warm conditions off the West Coast are as strong as anything in the historical record. The tropical El Niño recently declared by NOAA could extend the warm conditions and reduced productivity if it persists or intensifies through 2015.
"We are in some ways entering a situation we haven't seen before," said Cisco Werner, Director of the Southwest Fisheries Science Center in La Jolla, Calif. "That makes it all the more important to look at how these conditions affect the entire ecosystem because different components and different species may be affected differently."
For example, warmer conditions in the past often coincided with increases in sardines and warmer-water fish such as tuna and marlin and drops in anchovy and market squid. Salmon also fare poorly during warm conditions. Cooler conditions in contrast have often driven increases in anchovies, rockfish and squid. Anchovy and sardines have both remained at low levels in recent years, the report notes.
NOAA researchers will continue tracking how species respond to the shifting temperatures and conditions.
Salmon face the potential "double jeopardy" of low snowpack in the Northwest and rivers and streams shrunk by drought in California, plus reduced ocean productivity when juvenile salmon enter the ocean this year looking for food, Harvey said. However the impacts on salmon may not become apparent until a few years from now when the fish that enter the ocean this year would be expected to be caught in fisheries or return to the Columbia and other rivers as adults.
