Red king crabs hatch millions of larvae in Seward hatchery

Biologists hope raising king crab will lead to wild stock recovery

4/29/2008

Contacts

NR: SG-2008/NR270

king crab larvae
Red king crab larvae hatch, 2008. Click image to see larger version [1.8 MB]. (Photo courtesy Celeste Leroux, Alaska Sea Grant.)

Seward, Alaska—A baby boom of sorts has wrapped up in Seward.

The baby boom was the result of the hatch of several million red king crab larvae at the Alutiiq Pride Shellfish Hatchery. The twelve egg-bearing adult king crab that were collected from Bristol Bay last fall began releasing their larvae in mid-March.

The hatch is part of a research program, now in its second year, designed to help scientists and policy makers decide if large-scale hatcheries can be used to rebuild collapsed king crab populations in places like Kodiak and the Pribilof Islands.

The federal, state and industry–supported research program is called the Alaska King Crab Research, Rehabilitation and Biology (AKCRRAB) Program, and is run by the Alaska Sea Grant College Program at the University of Alaska Fairbanks.

“The egg hatch progressed steadily since the hatch began in March,” said Ben Daly, Sea Grant research biologist at the hatchery. “At this point we are pretty much at the end of the red king crab larvae release.”

Daly said the red king crabs at first released just a few hundred larvae per day, while some have released as many as 15,000 larvae per day. Daly said the crab hatch peaked a week ago, when the crabs collectively released about 100,000 larvae each day. Daly said from two to three million red king crab larvae have hatched.

Jim Swingle, research biologist at the Alutiiq Pride Shellfish Hatchery, said the adult crabs began eating less in the weeks leading up to the hatch.

“That was a sign that the hatch was getting close,” said Swingle. “We haven’t had any adult mortality and they all look really good. The eggs are healthy and developing well.”

Swingle said that as the adult crabs started to release their larvae, they were transferred to isolation chambers, allowing biologists to keep a close eye on each crab’s progress.

Over the next several months, scientists including University of Alaska Fairbanks graduate student Celeste Leroux will conduct experiments designed to evaluate the effect of diet, culturing effects, density, and other parameters on larval growth and survival.

"We learned so much about large-scale king crab culture in 2007 and I just can't wait to see what this year will bring," said Leroux.

Researchers also will conduct crab density studies to learn how to properly house large numbers of crabs, which are highly cannibalistic in their early life stages.

No crabs will be released into the wild, Daly said.

Six other red king crabs went to the federal NOAA Fisheries laboratory on Kodiak Island. These crab also have finished hatching their eggs, said research biologist Sara Persselin. Larvae from the crabs will be used in research to fine-tune the diet used to culture larval king crab.

Biologists with the AKCRRAB program believe what they learn can be used to improve wild king crab stock management, and may one day help decide if large-scale hatcheries could rebuild collapsed king crab stocks.

“Red king crab stocks around Kodiak have not recovered from their low numbers since the 1980s, and blue king crab stocks around the Pribilofs also have had their ups and downs,” said Brian Allee, director of Alaska Sea Grant. “The research we are engaged in now will give us the insight needed to decide whether crab stock rehabilitation using hatcheries is a viable option for rebuilding these stocks.”

AKCRRAB partners include the NOAA Aquaculture Program, United Fishermen’s Marketing Association, Central Bering Sea Fishermen’s Association, NOAA Fisheries, Chugach Regional Resources Commission/Alutiiq Pride Shellfish Hatchery, the University of Alaska Fairbanks School of Fisheries and Ocean Sciences, Gulf of Alaska Coastal Communities Coalition, Norton Sound Economic Development Corporation, and the Alaska Department of Fish and Game. The Alaska Sea Grant College Program coordinates the AKCRRAB Program.