Hatcheries examined as key to Alaska crab recovery
28 February 2006
Kodiak, Alaska—In the basement of the Alaska Fisheries Science Center on Kodiak Island, what just might be the key to rebuilding the state's crab fisheries swims nearly invisible within tall plastic tanks.
In the tanks, billions of tiny single-celled algae called diatoms have turned the water the color of tea. Brad Stevens, a research fisheries biologist at the center, is growing the algae as food for about 1000 juvenile Bering Sea blue king crab that were hatched and are being raised at the center. Stevens said growing the food was one of the biggest hurdles to successfully growing crab in captivity.
"It took us about four years to find just the right diatom strain that would grow in the water temperatures we had here," said Stevens. "We tried using local strains but we couldn't isolate them from other diatoms and the other diatoms would outgrow them."
First blue king crab zoea larvae on day of hatching. Courtesy Brad Stevens, Alaska Fisheries Science Center.
Stevens said cultivating crab in a hatchery and releasing them into the wild—much like the state's salmon ranching program—may one day help Alaska's depressed crab stocks recover. Stevens said his crab cultivation program is a small-scale model of the sort of operation that would be needed to rebuild the state's crab stocks.
"You'd have to grow and release many millions of crabs to have an effective program for rebuilding Alaska's crab," said Stevens. "As a first guess, somewhere between ten million and 100 million crabs would have to be released."
Raising crab in a hatchery is likely to be the easy part. Getting them to survive once released into the wild is another challenge altogether, Stevens said. Exactly what is needed to establish a successful crab enhancement program in Alaska is the subject of the Alaska Crab Enhancement and Rehabilitation Workshop in Kodiak March 14-16, 2006.
"Scientists around the world have made tremendous progress toward understanding and perfecting crab enhancement," said Brian Allee, director of the Alaska Sea Grant College Program at the University of Alaska Fairbanks. "This conference will help managers and fishermen better understand what we need to make it work here."
The Alaska Sea Grant College Program, the City and Borough of Kodiak, and the North Pacific Research Board sponsor the Alaska Crab Enhancement and Rehabilitation Workshop.
The conference will bring together an international array of scientists from Norway, Russia, Canada, Chile, Argentina, and Maryland's Chesapeake Bay who have led successful crab enhancement efforts.
Scientists will explain their programs and the lessons learned during talks focused on the challenges and potential of crab enhancement in Alaska. Experts also will discuss social and economic issues posed by crab enhancement and hear perspectives from commercial crab fishermen, seafood processors and industry associations.
Representatives from the North Pacific Fishery Management Council; Alaska Department of Commerce, Community and Economic Development; Smithsonian Estuarine Research Center; Northern Southeast Alaska Regional Aquaculture Association; Alaska Crab Coalition; Central Bering Sea Fishermen's Association; Trident Seafoods; and the Alaska Sea Grant Marine Advisory Program also will take part.
Ted Ames, a lobster fisherman from Stonington, Maine, is the conference's keynote speaker. Ames is leading an effort to establish a lobster hatchery to restock areas of Maine's Penobscot Bay. Ames and his family have been in commercial fishing since before the American Revolution. He has combined his master's degree in biochemistry with the knowledge of fishermen in an attempt to understand the underwater ecology of the Gulf of Maine.
Ames also helped create the Penobscot East Resource Center, which combines applied science and practical experience to help protect important fish habitats. In 2005, Ames received a $500,000 award from the John D. and Catherine T. MacArthur Foundation for his work to bridge the gap between scientists and fishermen over how to manage fish.
Blue king crab eyed embryo. The large black patch is the eye; yellow region is yolk; red splotches are chromatophores (color cells). Courtesy Brad Stevens, Alaska Fisheries Science Center.
Many of Alaska's crab fisheries have been in decline for years, due to overfishing and environmental change. Waters around Kodiak have been closed to red king crab fishing since the stock's catastrophic failure in 1982. Elsewhere, blue king crab fisheries around the Pribilof Islands and Saint Lawrence Island have been closed. Still other crab fisheries have endured periodic closings, shortened seasons and low harvest levels.
An Alaska crab enhancement program likely would be modeled on the state's hatchery program during the 1970s and 1980s that helped rebuild collapsed salmon stocks. A similar approach could someday seed Alaska's coastal waters with millions of crab.
Getting Alaskans talking about crab enhancement has been a goal for Alaska Sea Grant Director Brian Allee since the early 1990s when Allee was the director of the Alaska Department of Fish and Game Fisheries Rehabilitation and Enhancement Division, the agency that ran the state's salmon hatchery program.
For more information about the Alaska Crab Enhancement and Rehabilitation Workshop, contact Sherri Pristash, Meetings & Education Coordinator, 907-474-6701.