April 20, 2010

Alewives: Fish in troubled waters

Maine researchers delve into the mysterious decline of the alewife

By Beth Quimby bquimby@pressherald.com
Staff Writer

PORTLAND - The odor of dissected fish permeates the lab room at the Gulf of Maine Research Institute as Zach Whitener slices open a freshly caught alewife.

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Researcher Zach Whitener shows Kim Little, a University of New Hampshire student who will be interning at the Gulf of Maine Research Institute this summer, what to look for when examining alewives. The alewife population has dropped dramatically since the 1950s.

John Ewing/Staff Photographer

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“There is a lot of pseudoscience out there, but we really don’t know” much about alewives, says Jason Stockwell, a scientist at the Gulf of Maine Research Institute.

John Ewing/Staff Photographer

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ABOUT ALEWIVES
• Spawning alewives average 11 to 12 inches long and weigh about 8 ounces.
• They range from Labrador to South Carolina.
• They spawn when the water temperature is 55 to 60 degrees.
• Each female produces 60,000 to 100,000 eggs.
• Most adults return to sea after spawning.
• Eggs hatch in about six days in 60-degree water.
• The young fish go to sea from mid-July through early November.
• Fewer than 1 percent survive long enough to make it to sea.

Dumping the roe onto a scale, he snips and probes among the cartilage to extract the pinhead-sized ear bone.

It is a messy, odoriferous job, but Whitener said he doesn't mind.

"Quite the opposite," he said.

Whitener, who grew up on Long Island and graduated from Brown University last year, is part of a team of researchers working to unlock some of the mysteries surrounding the shimmering fish, which, along with the blueback herring, are known as river herring.

The nearly $600,000 project is funded by grants, including $225,000 from the National Fish and Wildlife Foundation. The foundation is dispersing $1.9 million in Maine from the $37 million in fines that Overseas Shipholding Group had to pay for repeatedly dumping waste oil off the East and West coasts. The rest of the money is from smaller state and federal grants.

Like the Atlantic salmon and other anadromous fish, which live in salt water but return to freshwater rivers and lakes to spawn, the alewife population has declined drastically. In the late 1950s, 70 million pounds of river herring were being landed along the East Coast annually, compared with fewer than 1 million pounds today. Researchers are trying to understand what is causing the decline.

"There is a lot of pseudoscience out there, but we really don't know," said Jason Stockwell, a scientist at the institute who is running the project with colleagues Theo Willis and Karen Wilson from the University of Southern Maine.

Some blame the population decline on dams, which prevent the fish from reaching their spawning grounds upriver; increased predation from resurgent populations of striped bass; overfishing; pollution; a change in the chemistry of lakes and ponds, or a combination of factors.

Some of the theories have holes. Water quality has improved dramatically after four decades of the Clean Water Act, and dam removals and the installation of fish passages along the East Coast are reopening access to spawning grounds.

Not much is known about alewives, Stockwell said. It is unclear where they migrate or whether the fish born in a particular river continue to school together or disperse.

Maine's alewife population is relatively healthy compared to other states, but scientists do not know why.

Massachusetts, Connecticut, Rhode Island, North Carolina and Virginia have placed a moratorium on fishing for alewives. Other states, including Maine, may be forced to follow due to new federal regulations that require states to prove that their existing alewife fisheries are sustainable.

"It will be up to the Atlantic States Marine Fisheries Commission," said Michael Brown, a marine resource scientist at the Maine Department of Marine Resources.

Alewives and other river herring are managed by the state along the coast of Maine and by the state and 41 municipalities in rivers and lakes, although only 15 communities have active fisheries.

The communities, such as Damariscotta, lease permits to harvesters. While river herring were once a popular food fish, today they are mainly used as lobster bait.

The annual catch in Maine is worth about $250,000, according to the Department of Marine Resources.

Alewives are far more valuable in other ways. They provide a protective cover from predators for the tiny number of Atlantic salmon that are migrating upriver at the same time. They are a food source for osprey, herons, bears, otters, cod, haddock, whales, seals and other animals.

When they die in lakes after spawning, they provide nutrients for phytoplankton.

Alewives returning to the Atlantic transfer phosphorus, which causes algae blooms, from lakes to the ocean.

(Continued on page 2)

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Alewives

  


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