Familiar fish are moving north: new study
“These global changes have implications for everyone in every part of the planet…” - University of British Columbia Researcher William Cheung “It’s not something in the distant future. It is well underway,” says famed marine biologist Boris Worm at Dalhousie University.
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Marine biologists on both ends of the country are in agreement - the warming of the oceans is having, and will have, an enormous affect on the way commercial fisheries in the western Atlantic will be conducted on every species now fished for human consumption, as well as those not now considered unfit to eat.
The scientists say familiar species like cod and haddock are being replaced by warm water species migrating northward as the ocean warms to temperatures suitable for their existence.
Dr. Daniel Pauly of the University of British Columbia Fisheries Centre was lead scientist on a new report, just published in Nature Magazine. He tells the Atlantic Fisherman: “Fish species always move with the temperature of the ocean. It used to happen randomly - what we call a “regime shift.”
These movements would take place according to variations in water temperature from year to year in specific areas where a fish species would congregate for a limited period of time - for example, the winter migration of cod in the Gulf of St. Lawrence.
But what the scientists are forecasting now is an entirely different bowl of fish broth.
“What is happening now is a definite trend,” says Pauly. “The direction is dominantly towards the poles and away from the equator, towards deeper and colder water, and that movement directly coincides with global warming and its measureable effect on ocean temperatures.
“Fish species will move towards the appropriate temperature in which their larvae and juvenile fish will thrive.”
Pauly warns that the current boom in lobster populations, and the larger catches fishermen are experiencing, is a “transient and not a permanent situation”.
“The mechanism is universal,” he says. “Fish cannot regulate their temperature, so individual species must move to reach their own preferred temperature. Some may adapt to warmer temperatures, but they need time to do it.”
The end result is a movement of fish northward and offshore towards deeper depths and colder water. That phenomenon inevitably will have a profound effect on the inshore fishery as larger vessels become necessary to travel farther and farther from home in search of fish. This effect has already been recorded in the lobster fishery . The southern edge of the range for homarus americanus has moved northward during the last decade , co-incident with the highest temperatures in recorded history currently being registered in the Gulf of Maine, and Atlantic Canada.
The northward movement, along with overfishing of stocks past the sustainable mark, has collapsed the groundfishery in waters off the northeastern states of the USA. That is seen in now non-existent populations of cod and haddock, with resulting severe economic havoc on inshore fishermen, and much reduced quotas on the diminishing populations that remain.
The effect of warming oceans is also seen in surf clams, which cannot move to seek more hospitable habitat. Populations are disappearing in shallow and warmer waters off Maryland, Virginia and Delaware, but the clams still thrive in the waters of northeastern New England.
The question is - how long will it take before the inshore fishery of the Atlantic region is in trouble, as the inevitable effects of global warming begin to impact the fishery?
In an email from Dr. Boris Worm, he says it’s hard to tell.
“Time frames are hard to pin down,” he says, “but there has been significant movement northwards of lobster and cod stocks over the past 30 years.”
Worm says, “This has not yet affected our region adversely. It is still well within the preferred temperature envelope of those species.”
And when politicians like Prince Edward Island’s Minister of Fisheries boasts that there is no conservation problem in the lobster fishery of his province, is he doing justice to the fishermen who are bound to feel the effects of climate change - sooner or later.
In the fishing ports of New England, the ugly reality of a fishless future for the inshore fishery has already hit home.
“We’re seeing significant declines in the number of boats that can fish,” says Richard Merrick, chief scientific advisor for the US government’s National Oceanic and Atmospheric Administration. “The crews that go along with that, they’re out of work.”
In Canadian terms, that’s a forecast for the destruction of a coastal society that pre-dates Canada itself by several centuries.
“Everything depends on some minimal level of predictability,” Glen Spain told the Washington Post. He works for the Pacific Coast Federation of Fishermen’s Associations. “And everything is becoming less and less predictable because of climate change.
“The biggest problem we have with fishery management is it assumes the future will look like the past. That’s no longer the case.”
Drs. Pauly and Cheung examined 52 distinct marine ecosystems around the globe in coming up with their conclusions on fish movement, noting that water temperatures rose in every ocean of the world during the last three decades.
“Fish are kind of the canary in the coal mine here, or the canary in the ocean,” says Worm. “It’s changing, and they are adapting. And the question is - how will we adapt. Or will we?”
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