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A Tale of Two Species (in The Age of Not Knowing)Robert Lundahl special to Salem-News.com
Underreported and less known is how climate change affects the oceans.
(LOS ANGELES, Calif.) - It was the best of times, it was the worst of times. It was the age of information, it was the age of not knowing.
As climate change has impacted fisheries and marine ecosystems across Alaska and the Pacific Northwest, the data gathered have been surprising. The same can be said for species in the warmer climate of the South Pacific.
SockeyeClimate change is likely the most serious threat to sockeye salmon. Among the impediments to success are "heat bombs" aka “The Blob,” a large warm water mass off the northwest coast of North America that is attributed to unusual weather conditions.
Nutrient poor, this thermal emitter has negatively impacted marine ecosytems and may disorient salmon trying to find their way back to natal streams.
The increase of carbon dioxide in the atmosphere, and therefore in the ocean, is causing the ocean acidification significantly impacting the salmon’s food chain.
Back on land, warming weather has increased the water temperatures in the rivers and streams, increasing the growth of parasites, spreading disease, and attracting predators.
Sockeye salmon and climate change (World Wildlife Fund)
Studies indicate that tidewater glaciers deposit nutrient material from the land to the water that stimulates the growth of marine plankton, lunch to the recently escaped juvenile salmon (smolts).
We are new to this process of collecting data points and have not yet transformed our previously limited understanding of planetary and thermographic systems into a clearer and more predictive "picture."
The media mainly focus on how climate change, through higher temperatures, storms, and sea levels, affects us here on land.
Underreported and less known is how the oceans change too, and how these changes may have economic consequences. Warm ocean temperatures are causing widespread coral bleaching in the Caribbean. In Alaska, Warm ocean temperatures are causing some species to move north.
Will the U.S. scientists and fishery managers have enough data to react? Will subsistence villages, family operations and shore-based boats be able to adapt as fish move away?
According to Rutgers:
"Fish are sensitive to the temperature of the water where they live, and as it becomes too warm, populations often shift to where the water temperature is right for them.
"This process has already begun, though at different rates in different places. As climate change continues and the oceans warm up, the study shows, more species of fish will move north to where the temperature range is habitable for them."
Researchers have found that "recent shifts in the geographic distribution of marine species have been linked to shifts in preferred thermal habitats.
"Species from the U.S. and Canadian west coast including the Gulf of Alaska had the highest projected magnitude shifts in distribution, and many species shifted more than 1000 km under the high greenhouse gas emissions scenario."
Following a strong mitigation scenario, presumably this would not be the case.
"Unfortunately, some of the species that are responding well to global warming, such as arrowtooth flounder, spiny dogfish and Pacific and Jack mackerel, are species that prey on species that are highly valuable for Alaska's commercial fishermen," said Kruse.
"Arrowtooth flounder not only eat our high-value species, but they are also species that have a low market value."
Kruse said that the warming trend in Alaska waters are also punctuated by temperature spikes from more intense and more frequent El Ninos that may provide windows into Alaska's warmer future.
Pacific salmon appear to be expanding their range into Arctic ecosystems and may be acting as effective sentinels of climate change.
Salmon harvests voluntarily reported through the Pacific Salmon Collection Program (PSCP) suggest recent increases in both the abundance and distribution of Pacific salmon in the Arctic over the past decade.
Pacific Salmon in the Arctic: Harbingers of Change
Blue FinPacific Island nations and territories are a powerhouse in the fishing industry, contributing more than a third of the global tuna catch despite their small size.
For these islands however, the tide could soon go out.
(Conservation International) Fueled by greenhouse gas emissions, ocean warming will alter the habitats of tuna, causing these fish to move outside the jurisdictions — or Exclusive Economic Zones (EEZs) — of many Pacific Islands.
Using modelling to predict how tuna stocks could move by 2050, a team of experts — led by Conservation International’s Johann Bell — found that an exodus of tuna could cut the average catch by a staggering 20 percent in 10 Pacific Island states, from Palau in the west to Kiribati in the east.
Researchers from Spanish research institute AZTI investigated the patterns of six tuna species, including albacore, Atlantic bluefin and yellowfin, between 1958 and 2004 and found that 20 of 22 tuna stocks studied had shifted their ranges towards cooler waters because of climate change.
"On average, tuna habitat distribution limits have shifted poleward 6.5 km (4 miles) per decade in the Northern Hemisphere and 5.5 km (3.1 miles) per decade in the Southern Hemisphere," the researchers wrote.
"Larger tuna distribution shifts and changes in abundance are expected in the future, especially by the end of the century."
"Under science-based management, increasing uncertainty translates into more precaution, which means more conservative fish harvests in Alaska."
Professor Kruse concludes by recommending more research, including improved ecosystem monitoring, more process-oriented studies, increased climate-fisheries modeling and the expansion of ecosystem-based fisheries management.
He forecasts that sightings of ocean sunfish and albacore tuna may become much more common in the future, as far north as the Bering Sea.
Rising global temperatures, due to human causation, can influence a wide array of changes in the earth’s climate including extreme weather, ocean acidification, and sea level rise.
The impacts of climate change will continue to intensify unless agreements are enacted to reduce our anthropogenic footprint.
Articles for November 17, 2021 | Articles for November 18, 2021
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