Already, scientists are observing shifts in species distribution around the world. After an 800,000-year absence, a species of Pacific diatom, a shell-encased alga, has recently appeared in the North Atlantic. Scientists are unsure of its impact, but they take its arrival as evidence that certain conditions absent for nearly a million years – lack of sea ice, prevailing winds – are reemerging.
Northern countries like Norway and Iceland have seen an influx of more southerly fish species. They’re not complaining, because they’re likely to catch more fish. Blue mussels, once found only as far north as Norway’s coast, meanwhile, have colonized the Svalbard archipelago, more than 400 miles from Scandinavia.
Salmon spawn in ever more northerly Alaskan rivers. And walleye pollock, the largest US fishery by volume, appear to be shifting into Russian waters. This development has implications for both US fishermen and stock health, says Daniel Pauly, a fisheries professor at the University of British Columbia, Vancouver. In US waters, pollock is carefully managed, he says – but not in Russian waters.
If a fish stock moves out of a particular area, he says, it takes much more time to work out new international fishing treaties than it does to fish down the stock.