The basic makeup of the ocean waters off the Northeast and the mid-Atlantic region has fundamentally changed in the past 40 years because of climate change, commercial fishing pressures and growing coastal populations, according to a new report.
The 2009 Ecosystem Status Report says fish populations in U.S. waters from North Carolina to Maine have moved from their traditional home grounds because of a changing environment and human activities.
The report is the broadest study that researchers have undertaken for U.S. waters in the Northwest Atlantic Ocean, Michael Fogarty, who headed the study, said Tuesday. The findings show how interconnected the ecosystem is, he said.
"We need to consider these interrelationships and connections. In some cases they aren't obvious on the surface," said Fogarty, head of the ecosystem assessment program at the NOAA Northeast Fisheries Science Center in Falmouth, Mass. "If we ignore them or don't understand them, then we could come away with the wrong picture of what's driving things."
Fogarty's research team looked at variables such as water temperatures, circulation patterns, fishing pressure, pollution and habitat loss in a 100,000-square-mile area off the Northeast and mid-Atlantic coast. The area is one of 64 regions in the world's oceans designated as a large marine ecosystem.
A recurring theme of the report is that the ecosystem is changing.
Commercial fishing practices have contributed to changes in the composition of the region's fishery population, which is now dominated by species such as mackerel, herring, skates and small sharks, the report says.
The change in the fish population mix is being felt by other species. For example, spiny dogfish sharks feed on silver hake, putting that type of bottom-dwelling fish under additional pressure.
The region's water temperatures are also on the rise, which affects where fish live.
Fish that prefer warmer waters — such as croaker in the Mid-Atlantic — are increasing in abundance in the region, Fogarty said. At the same time, fish such as cod are moving north in search of colder waters, causing a shift in their population range.
If the waters continue to get warmer, traditional fishing grounds could be hurt.
"If the projections for climate change hold, places like Georges Bank could potentially get marginal," he said, referring to fishing grounds off the Massachusetts coast.
There are some bright spots in the report. Scallop populations and lobster stocks in the Gulf of Maine are strong, and haddock and redfish populations have staged comebacks in recent years.
Still, the pressures on the ecosystem are likely to increase with climate change, coastal development and fishing activities. A better understanding of those pressures and will lead to better management and mitigation strategies, Fogarty said.