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
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
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
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
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
for more stories from this issue of UMaine Today Magazine.