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September / October 2004

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Keeping Cod Down on the Farm

Photo by Fred J. Field

Keeping Cod Down on the Farm
UMaine researchers are working with regional scientists to overcome barriers to raising the once abundant fish in captivity

About the Photo: At UMaine's Center for Cooperative Aquaculture Research (CCAR) in Franklin, graduate researcher Bill Palmer (top photo) and Associate Professor of Aquaculture Nutrition Linda Kling examine young cod.

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It's late spring, but the wind on Down East Maine's Cobscook Bay still has a bite. Scientists in winter jackets turn up their collars as they peer at a video screen at an aquaculture pen near Eastport. They're watching live footage captured by an underwater camera that is monitoring thousands of Atlantic cod (Gadus morhua) from the bottom of the pen. On screen, fish silhouettes meander against a white sky.

It's the only look that Austin Dinsmore, manager for International Aqua Foods USA's Eastport operations, and University of Maine scientists Linda Kling, Nick Brown and Bill Palmer will get of their cod today. The edge of the 50-foot-wide circular pen is only a few feet away, but the water is quiet. The fish have hunkered down well below the surface, wary of their new surroundings. They are among the pioneers the latest hatchery-raised Atlantic cod to be placed in aquaculture pens, following in the wake of similar efforts in New Brunswick and New Hampshire.

"We are investigating the potential of other species of fish as a viable alternative to Atlantic salmon for Maine aquaculture," says Kling, an animal nutritionist. Brown, manager of UMaine's Center for Cooperative Aquaculture Research (CCAR) in Franklin, Maine; UMaine food scientist Denise Skonberg; and Kling are working with the aquaculture industry to determine the feasibility of raising cod from egg to market in Maine.

In a sense, the cod at Eastport have come home. They are the progeny of wild fish caught a few miles from the International Aqua Foods pen in 2000. Those wild fish don't have a pedigree, but like prize racehorses, they have been tended with loving care at CCAR. They are the broodstock the Adam and Eve, if you will of an emerging cod aquaculture industry.

Linda Kling and Bill Palmer
In Cobscook Bay near Eastport, Maine, University of Maine scientists Linda Kling and Bill Palmer use a video monitor to see live underwater images of some of the thousands of 2-year-old cod being grown in captivity. The cod will stay in the aquaculture pens for almost 15 months, and are expected to be ready for market next year.

Photo by Fred J. Field

Supported by a $358,000 federal Department of Commerce grant, the cod-rearing project is one of many research efforts around the world aimed at developing alternative species for fish farms. In the U.S., farmers and scientists are raising red snapper in Hawaii, white sea bass in California, cobia in Florida, winter flounder and cod in New Hampshire, and halibut and cod in Maine. Spurred on by declining wild fish stocks, aquaculture is already meeting a significant share of the nation's seafood demand.

In 2002, the National Marine Fisheries Service estimated that share at about 30 percent. The U.S. Ocean Commission estimates the value of marine and freshwater aquaculture production in the U.S. at nearly $1 billion.

International Aqua Foods USA's parent company, Stolt Sea Farm, is already raising cod commercially in Norway. The king of groundfish also is a natural for the Gulf of Maine's cold waters. A resident of far northern seas, cod thrive at low temperatures. Brown notes that they are more resilient than Atlantic salmon, which still account for the largest portion of Maine's aquaculture industry.

In the wild, cod numbers have declined significantly worldwide in the past 30 years. Overfishing is thought to be a primary cause, but scientists consider changing climate and water temperatures to be critical factors as well.

In a spring 2004 report, the Maine Aquaculture Task Force chaired by Paul Anderson, director of the Maine Sea Grant program, acknowledged cod as a "new and promising species" under development in Maine. Nevertheless, success has been slow.

The roots of cod farming go back more than a century in Norway, but it wasn't until the 1980s that techniques for feeding the newly hatched larvae were worked out in detail. Cod larvae are picky eaters. They need live zooplankton raised in culturing tanks, an expensive process. As juvenile fish, they continue to prefer live prey.

In the mid-1990s, Kling found a way to increase the survival of larval cod to the juvenile stage. In a system that recirculates and treats water at the Aquaculture Research Center in Orono, she achieved higher survival rates than those reported in previous studies. She also created a pellet feed cod would eat early in their development.

She and other researchers continue to work on an "early weaning diet" that could ease the transition away from more expensive live feeds. "Early weaning has not been embraced by the industry because it results in reduced growth rates. That diet is still in the future," she says.

Nevertheless, these were important milestones. Similar research efforts were under way in Canada and Europe. Cod aquaculture was on its way.

Since then, efforts to raise cod have accelerated. Norwegian companies are selling farm-raised cod, and the government has set a goal of producing 200,000 tons per year, Brown notes. For comparison, the World Wildlife Federation has reported that fishermen harvested about 950,000 tons of wild cod worldwide in 2000, down from 3.1 million tons in 1970.

On this continent, cod farming in New England was slowed by disease (viral nervous necrosis, caused by nodavirus) and a Newfoundland hatchery fire. Fish now in pens in New Brunswick and Eastport may be the first to reach North American markets.

In addition to the economics of farm-raised cod, the project is looking at disease potential, environmental impacts, feeding behavior, feed utilization and consumer acceptance. At CCAR, Brown is establishing a quarantine system for fish brought in as potential broodstock to prevent diseases from being carried into the hatchery.

No one knows how the fish will fare in a net pen, but the industry is applying lessons learned in raising salmon. The cod are fed a dry pellet that is higher in protein and lower in fat than salmon feed (and $200 to $300 per ton more expensive). Too much fat leads to liver problems in cod, says Kling.

Dinsmore and other cod farmers also are vigilant when it comes to fish behavior. "We're using a specially designed net with smaller mesh and a tougher twine because cod behave differently from salmon," he says. Cod will be kept in the pen for 15 months. The pen must then be allowed to lie fallow, according to regulations developed to minimize the chances for disease.

Genetic diversity has been a concern in the salmon industry, but the cod in Eastport are reared from wild fish and are not genetically different from them, says Brown. Plans call for the fish at Eastport to be harvested in fall 2005. UMaine food scientist Denise Skonberg will then evaluate the meat for consumer acceptance and yield.

" Farm-raised salmon tend to produce more filet per pound than wild salmon. We don't know what it will be like with cod," she says. Her research will focus on nutritional qualities, such as fat, protein and mineral content; the average weight of processed fish; and differences between wild and farm-raised cod.

As cod aquaculture proceeds in North America and Europe, fishermen, scientists and governments remain concerned with wild cod fisheries recovery. Aquaculture is unlikely to pose a threat, says Brown. "Aquaculture won't compete on price with boats hauling in nets full of wild, caught cod. The fish we're raising will go to high-end uses the fresh filet and possibly the live market, like restaurants where customers pick the fish they want to eat out of a tank."

The feasibility of cod farming in Maine is dependent on economics, Brown adds. Once the fish are harvested and the production data have been collected at the end of the project, Brown and Palmer will work together with the economists at Stolt Sea Farm to develop a business model for cod aquaculture. Stolt will use the model to determine whether to expand the industry in Maine.

by Nick Houtman
September-October, 2004

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