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Jonah crab is now the dominant species in the Gulf of Maine.

Drawing courtesy of NOAA Photos

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Jonah crab signals a new phase in Gulf of Maine

Jonah crab has overtaken cod’s 4,500-year dominance in the Gulf of Maine, signaling a new phase in the biology and fisheries of coastal waters. Other changes also have occurred, such as the near absence of kelp-eating sea urchins. As a result, expansive kelp beds now flourish.

The findings not only could mean long-term biological consequences for coastal fisheries in Maine, but in other heavily fished parts of the world’s oceans as well, according to a recent report in the journal Ecosystems.

The authors of the report, Professor Robert Steneck of the University of Maine’s Darling Marine Center, and former UMaine graduate students John Vavrinec and Amanda Leland, analyzed fishing records and previous studies to look for changes caused by fishing pressure in marine ecosystems.

They broke down the data into three phases in the nutritional or trophic structure of kelp forests in the Gulf. Phase I, which had predators such as Atlantic cod, haddock and wolfish, lasted for more than 4,000 years. Phase 2, characterized by sea urchins, lasted from the 1970s to the 1990s. And Phase 3, dominated by large crabs and other invertebrate predators, has developed since 1995.

Each phase resulted from fisheries-induced changes that altered the balance in species of the Gulf. The drastic reduction in cod and other top predators over the last century is one example. In addition, ancient coastal middens indicate that Native American fishing activities were starting to affect near shore ecosystems several thousand years ago. And colonial and modern fish landing records show that the changes accelerated as new fishing technologies emerged.

“The long dominance of predators has given way to many species playing ‘king of the hill,’” says Steneck. “While there is no fear of these species going extinct, entire sections of the food web have become so rare that they no longer perform critical ecological functions in the marine community.”

Sperm whales and the bends

Marine mammals were thought to be immune to the bone damage human divers suffer as a result of decompression sickness, or the bends. But a sperm whale found dead on a Nantucket Island beach in 2002 caused scientists to question that belief. The whale’s skeleton showed signs of a progressive patchy bone death under certain joint surfaces.

The damage intrigued scientists at Woods Hole Oceanographic Institution (WHOI), who studied more whale skeletons. In research published recently in the journal Science, they reported osteonecrosis, a progressive death of bone cells, in the sperm whales they analyzed. The most likely cause, they said, is tissue damage from nitrogen bubbles that form when the mammals surface too quickly. The change in pressure decreases blood flow to the joint surfaces, causing the bone to die.

“Sperm whales may be neither anatomically not physiologically immune to the effects of deep diving,” they wrote.

Michael Moore, a WHOI research specialist in biology, and Greg Early, a guest investigator at WHOI’s Biology Shore Lab, found lesions such as pits and signs of erosion in the rib and chevron bones of sperm whales. Those lesions become more severe with age, and are found in animals from the Atlantic and Pacific Oceans that died up to 111 years ago.

The two scientists studied 16 partial or complete sperm whale skeletons from both oceans that were in museums. They discovered areas of dead cells in bones attached to the backbone, such as the rib bones and other small bones in the sperm whale’s tail area.

Moore and Early suspect that sperm whales normally manage their surfacing behavior to minimize the problem with bubbles. But they are at risk if they surface too quickly, which happens, for example, if they are startled by loud underwater noises such as sonar or seismic survey guns. Similar acute decompression-like sickness has been observed in beaked whales exposed to military sonar.

—Lori Valigra

Safer seas for seabirds?

Legislation aimed to better protect Canadian waters and the marine environment, plus send a strong message to polluters, has been presented for a Second Reading in the House of Commons. Bill C-15, An Act to amend the Migratory Birds Convention Act (1994) and the Canadian Environmental Protection Act (1999), calls for increased fines of up to $1 million and additional powers for enforcement officials to redirect and detain ships suspected of having polluted Canadian ocean waters. Each year, at least 300,000 seabirds are killed off the coast of Atlantic Canada as a result of oily bilge released from passing ships.

In other measures to control illegal oil dumping, Transport Canada, one of three agencies that conducts surveillance to detect marine pollution from ships, recently purchased new marine pollution aerial surveillance equipment to strengthen the agency’s National Aerial Surveillance Program. The $2.3 million contract covers the purchase of the equipment, as well as the on-board crew training. The equipment will be installed in Transport Canada's aerial surveillance aircraft and crews will be trained on its use over the coming months.

Currently, the surveillance relies on visual detection from crew on board an aircraft, who can survey approximately two nautical miles on each side of the aircraft. The new equipment will be able to detect surface anomalies, such as oil, up to approximately 25 nautical miles on each side of the aircraft. The equipment, according to a Transport Canada press release, will significantly increase the ability to detect illegal discharges from passing vessels even in conditions of reduced visibility, such as darkness or low cloud cover. The system will also assist the Department of Fisheries and Oceans, Canadian Coast Guard and Environment Canada with containment and cleanup operations by detecting, tracking and helping determine the characteristics of oil slicks.

In recent years, remote sensing instruments have also been used onboard aircraft and satellites to detect and track oil spills (see Gulf of Maine Times, Winter 2002).

To get an overall sense of the devastation to seabirds from oil spills in Canadian waters see Birds Oiled at Sea at www.atl.ec.gc.ca/boas/index_e.html.

Whale deaths raise major concern

The North Atlantic right whale is so rare that that scientists who study them know them by name. That’s why researchers were especially distressed this winter after four of the fewer than 350 right whales left in the world had been found dead along the eastern seaboard of the United States.

In November a Navy vessel struck and killed a pregnant right whale off the Virginia coast. In December another whale was found dead 86 miles (138 kilometers) east of Nantucket. Then came the death of Bolo, a 45-foot (13.7-meter) female, who had given birth to at least six calves, the most ever recorded for a right whale. She was found dead off Nantucket Island on January 10. Two days later, another female right whale, named Lucky, was found dead off the coast of Georgia. Lucky, named for scars she received from a previous ship-strike, was pregnant with her first known calf.

Despite the distressing news, there is some reason to cheer. By January the calf count was already 13—extremely high when compared to recent years. Among the new mothers was Calvin, a right whale that was orphaned at age eight months in 1992, when her mother was hit by a ship in the Bay of Fundy. The Coast Guard encountered Calvin with her newborn calf off the coast of Wrightsville Beach, North Carolina.

According to the New England Aquarium, 16 calves were born in 2004, 19 in 2003. The biggest right whale “baby boom” in recent years was 2001, when 31 calves were born.

“The calving rate is very exciting,” Dr. Charles “Stormy” Mayo, senior scientist at the Center for Coastal Studies, told the Cape Cod Times. “But the mortality rate is too high in my judgment to support the population.”

—Andi Rierden

Model partnership for the Penobscot

The restoration of Maine’s Penobscot River is one step closer to becoming a reality since the Penobscot Partners coalition reached a final agreement last June that will result in the removal of two hydro-electric dams and the decommissioning of a third.

The coalition, comprised of the energy company PPL Corporation, conservation groups, state and federal government agencies and the Penobscot Indian Nation, has taken an innovative approach to river restoration that balances environmental interests with hydropower production.

Under the plan submitted to the Federal Energy Regulatory Commission last summer, the Penobscot River Restoration Trust has a five-year window of opportunity to purchase three dams from PPL at $25 million. The Trust is a non-profit formed last May to oversee the restoration effort. The Trust’s board of directors is comprised of members of the conservation groups and the Penobscot Indian Nation.

After the purchase, and likely by 2010, the lowermost dams on the river—Veazie and Great Works—will be demolished and the Howland Dam will be decommissioned and fitted with a fish bypass. PPL will improve fish passage at four other dams.

Opening 500 miles of river will bring back migratory fish-runs and give native species, such as the endangered Atlantic salmon, access to historic spawning grounds. The Penobscot has the largest wild salmon run in New England and is crucial to the recovery of the species. Revitalized fisheries will enable the Penobscot Indians to exercise their sustenance fishing rights, which the tribe has been unable to do above the Veazie Dam for a century.

PPL will have the option to retain 90 percent of its energy production by increasing output at six other dams on the Penobscot and its tributaries. The company also has the assurance that other coalition members will not challenge the federal relicensing of its remaining dams.

Fundraising is now underway to collect $25 million for the purchase of the three dams. In December, Maine Senators Olympia Snowe and Susan Collins secured $1 million in federal funds from the National Oceanic and Atmospheric Administration for the project.

The Penobscot Partners formed after PPL took over the hydropower facilities on the river in the late 1990s to end the cycle of legal wrangling over issues of dam construction and relicensing that had occurred in the past. It has coordinated the effort to bring the diverse group of stakeholders to a compromise.

All parties involved have unique goals, but the coalition works because all share a common objective in restoring the river, said Laura Rose Day, director of the Penobscot Partners.

– Maureen Kelly


© 2005 The Gulf of Maine Times