Nature Notes: A Warmer Arctic
By the turn of the last century, we knew very little about the Arctic and an awful lot about the Antarctic. The Antarctic was sexy, the Arctic dull.
The Arctic Ocean was covered with ice 12 months of the year and thus difficult to visit, let alone study. The Antarctic Ocean, a jigsaw puzzle made up of the southern extremities of the Atlantic, Pacific, and Indian Oceans, surrounded a large landmass, Antarctica, mountainous and covered with glacial ice for the most part. As far as continents go, it is the fifth largest, about two times the size of Australia. Through the ages, exploration of land always preceded the exploration of the seas, and after World War II, the Antarctic became an object of international study.
But when it became obvious by the 1980s that the world climate was heating up and sea level was rising, the Arctic started warming up commensurately and the sea ice started melting. By the year 2000, Arctic natives like the Inuit were finding that their traditional food stocks such as narwhals were waning, polar bears were having a tough time of it, and the marine vertebrate composition, particularly the fish species, were increasing in number. The cold water-loving fish fauna was still there under the ice, but new species from the Pacific and Atlantic were moving in as the ice melted and the water warmed.
Only 20,000 years ago, the last glaciation was covering all of Canada, Iceland, Greenland, Baffin Island, a third of the United States, and about half of Eurasia. Many of the northern species were pushed south. Several, like the woolly mammoth, became extinct. The tropics were the place to be, and they had many more bird species than they have today.
The glaciers melted back to the north until eventually only Alaska, the very northern edges of Canada, Iceland, Greenland, Scandinavia, and northern Siberia were still glaciated. Various vertebrates, in particular those that were very mobile, like birds, started moving back north after a long retreat. Annual north-south migrations came into being. Many species of fish joined in the migration, as did some mammals, especially marine ones, and even sea reptiles, sea turtles in particular. Many nonmigratory species moved north: Carolina wrens, mocking birds, cardinals, red-bellied woodpeckers, tufted titmice, and blue jays among them.
Very few species are going in the other directions; that won’t happen until the next glaciation, if there is one yet to be.
What most people, except for a few scientists and a great many fishermen, didn’t know is that there are almost as many migrating fish species as migrating bird species. Just as predatory migrating hawks such as the broad-winged hawk and the osprey have been migrating north to reproduce after a relaxing winter in the south, so, too, have the predatory fish been migrating north in the spring and summer to spawn and feed. Locally, commercial and recreational fishermen have been catching more and more of these southern species that have been extending their populations north. It was only natural that eventually, as global warming continued, the Arctic Ocean would become populated with species of fish that were more southern to begin with.
And that is what has been happening in this century. Oddly, during an unusual global warming period between 1920 and 1940, which was confined mostly to Europe, the fish populations and the fish catches around Greenland and Iceland contained several temperate and southern species. The marine scientist George A. Rose studied the harvests of fishermen and scientists plying those waters during that period and discovered a great influx of fish that were absent from before that period and again after that brief warming spell had run its course. Historically, fishermen catch what is most available, especially if it is edible.
During that warming, the northwestern Atlantic did not experience a change in temperature. The waters remained cold and the fish species composition remained static. But now the same influx of warmer water species is being experienced in the Arctic Ocean and it is probably attributable to global warming. The Greenland glaciers have been melting precipitously, as have the ones in Alaska. This time, the warming is occurring around the entire Arctic Circle. The United States Geological Survey has been studying the fish population in the Chukchi and Beaufort Seas of the Arctic Ocean, as reported in a 2016 edition of Alaska Dispatch News by Yereth Rosen. According to her report, that unit of the Department of Interior has discovered 109 fish species in those waters, at least 20 more than were found in previous studies. Another 63 or so are poised at the entrances to that ocean, the Bering and Greenland Seas, and no doubt, some of these have already passed through.
This continued “northerning” of fish species presents problems. The ecology of the Arctic Ocean, no doubt, is in for some major changes, many of which will be manmade, such as oil drilling and sightseeing cruises. Less than 10 percent of the Antarctic Ocean is made up of coastal waters protected by existing regulations. The rest is protected from nonindigenous fishing by a 2017 agreement signed by nine territorially involved nations and the European Union to prohibit commercial fishing in the rest of the ocean for the next 16 years. However, there is no such agreement in place with respect to oil drilling or seabed mining.
One of the great advantages the Arctic Ocean displays today is its off-the-beaten-track location and its very, very small coastal human population. Thus there is almost no plastic debris to be found in it of the kind that is plaguing the other five world oceans. Hooray for that fact!
Larry Penny can be reached via email at Larrypenny9@gmail.com.