November 12, 2009

Fish Populations In North Atlantic Changing

For years New England fishermen have had to steam farther and farther from shore to find the cod, haddock and winter flounder that make up their catches, The Associated Press reported.

According to a new federal study documenting the warming waters of the North Atlantic, the typical fish most often caught for commercial purposes could eventually change to the Atlantic croaker, red hake and summer flounder normally found to the south.

Janet Nye, a fishery biologist with the National Oceanic and Atmospheric Administration and the lead author of the study, said fishermen are businessmen, so if they have to go farther and deeper to catch the fish that we like to eat, eventually it won't be economical to do that.

Nye, who works at the Northeast Fisheries Science Center in Woods Hole, Mass, said in the near future the fish we enjoy might not be in our local seafood store, or maybe it will be more expensive.

"So I think there'll be a natural, hopefully slow, switch to different seafoods," she said.

The research, published in the journal Marine Ecology Progress Series, saw Nye and three other NOAA biologists analyzing water temperature trends from North Carolina to the Canadian border off Maine from 1968 to 2007.

Fish survey data collected each spring allowed the team to access where the fish were caught and how abundant they were.

The study mostly focused around the familiar New England species, as well as lesser-known fish such as longhorn sculpin and blackbelly rosefish.

The distribution range of 24 of the 36 stocks studied showed they had changed in unison with the rising water temperatures that have been occurring off the Northeast since the 1970s.

While that temperature rise was less than half a degree Fahrenheit, on average, it's been enough to cause fish to slowly move to areas with more favorable temperatures.

The blackbelly rosefish moved more than 200 miles to the northeast during the years studied.

Among commercial species, movements of more than 100 miles were observed for southern stocks of yellowtail flounder and red hake, as well as American shad and alewives.

The report showed that some fish exhibited little movement to the north, but rather moved to deeper waters where temperatures are lower.

Tom Dempsey of the Cape Cod Commercial Hook Fishermen's Association said small-boat fishermen on Cape Cod caught most of their haddock and flounder, as well as the peninsula's namesake fish, in waters close to shore 20 years ago. But now he said they have to travel as far 100 miles offshore to find those same fish.

Fishermen in Massachusetts are also catching more fish traditionally found in the Middle Atlantic - Atlantic croaker, in particular, usually caught off Virginia and North Carolina.

Dempsey said it is hard to get a handle on exactly how much of that is directly impacted by climate change.

"There are a number of other factors that have been at play, one being over-harvesting in inshore areas and, subsequently, ecological changes as inshore areas have become dominated in a lot of areas by spiny dogfish populations," he said.

Jason Link, a NOAA fisheries biologist and a co-author of the study, said the research is just one piece of the puzzle in figuring out the factors that influence ocean species.

Climate change is the driving factor, according to the report. However, Link said other influences - such as fishing pressure and long-term natural cycles in ocean temperatures and atmospheric conditions - play a role.

Link said they are now looking at how much of this movement to colder waters is perhaps related to the environment as opposed to how much is due to fishing.

"I don't think this paper totally answers that question," he added.

Jay Odell, a marine specialist with The Nature Conservancy in Richmond, Va., said that while the report documents the movement of fish in the Northeast and the Middle Atlantic, there's evidence to suggest that marine organisms in southern U.S. waters are also moving north.

He said that in recent years, Sea turtles that normally nest on beaches in North Carolina and south have been nesting in Virginia and Maryland, possibly because of rising water temperatures.


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