Research on Acidification Aims to Assure Crab Stocks a Future
A summer's worth of research, including some 400 bottom tows, is over, giving federal researchers the data needed to proceed with recommending crab harvest totals that will assure a sustainable crab fishery.
The ultimate goal, says Bob Foy, director of the National Marine Fisheries Service crab laboratory at Kodiak, is to come up with a biomass estimate, in particular the number of mature males, to proceed with stock assessment models, and set overfishing levels by September's end.
That done, the state of Alaska, with whom NMFS co-manages the state's shellfish fisheries will proceed to set the total allowable catch for harvests for the 2016-2017 season, including Bristol Bay red king crab, by the first week of October.
The North Pacific Fishery Management Council's Bering Sea/Aleutian Islands crab plan team is scheduled to present its report to the council in Anchorage in October.
"It all happens very fast," said Foy. It's one of the fastest turnarounds of data information into the fishery management process, with the collection completed by Aug. 1, and the TAC set within 60 days.
The biomass estimate itself involves counting juveniles, males and female crab collected in bottom tows, studying their shell condition to determine their age and reproductive status.
What with 2012 being one of the coldest years in recent times, and then the last two years being two of the warmest in recent times, researchers are seeing differences in movement patterns and distribution changes in crab species, including when the crab molt. Weather forecasters are anticipating a La Nina, or cooler than average sea surface temperatures for the 2016-2017 crab fisheries season, a change from El Nino, or a phase associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific.
Along with monitoring the transition from El Nino to La Nina, the NOAA crab laboratory at Kodiak is engaged in a race against time to figure out ways to help crab survive in ocean conditions of growing acidification.
To that end, NOAA Fisheries is a participant in the Alaska King crab Research, Rehabilitation and Biology Program, also known as AKCRRAB, which conducts research aimed at hatching and rearing wild red and blue king crabs in a large-scale hatchery setting.
Their mission is to understand the large-scale culturing needs of wild red and blue king crab stocks, and to perfect strategies for hatching and rearing king crab to a stage where they can be released into the wild and contribute to reversing low wild stock abundance in Alaska.
Acquiring this knowledge base, the Alaska Sea Grant program notes, will aid policymakers in making informed decisions about whether to one day pursue active rehabilitation of depressed wild king crab stocks through hatchery enhancement.
Other partners in AKCRRAB include the Aleutian Pribilof Island Community Development Association, the Alutiiq Pride Shellfish Hatchery, Central bering sea Fishermen's Association, Chugach Regional Resources Commission, the University of Alaska Marine Advisory Program, NOAA Aquaculture, the Norton Sound Economic Development Corp., United Fishermen's Marketing Association, and the School of Fisheries and Ocean Sciences at the University of Alaska Fairbanks.
Additional support for AKCRRAB has come from the Alaska bering sea Crabbers, Alaska Legislature, bering sea Fisheries Research Foundation, the Groundfish Forum, Gulf of Alaska Coastal Communities Coalition, Kenai Peninsula Borough, Kodiak Island Borough, city of Kodiak, the Pribilof Island communities of St. Paul and St. George, the city of Seward and Santa Monica Seafoods.
"We've been raising red king crab, working with the (Alutiiq Pride Shellfish) hatchery in Seward," Foy said.
The project has involved putting juvenile crab raised at the hatchery into the waters of the Trident Basin at Kodiak in varied ages and densities, and trying to figure out how to reduce mortality rates once crab get into the ocean.
There are plans to do more outstocking research next summer (of red king crab) and then start working with blue king crab as well, in the Pribilofs off of St. Paul Island, Foy said. The Pribilof project, a joint effort of NOAA and UAF, will be funded through the North Pacific Research Board. The Alutiig Pride Shellfish Hatchery has been working with blue king crab for several years and the new project will be similar to that being conducted at Kodiak, starting with running experiments to see how the crab from the hatchery react with the ocean environment.
Right now the experimental work is in Trident Basin and is done with scuba diving.
The crab stay on the bottom, mixed in with the plant material. "The mortality rate was 98 percent right off the bat, but that is what it is in the wild, probably due o predators- small fish and other invertebrates, Foy said.
Juvenile crabs eat small invertebrates and algae, which are abundant in that habitat. And there is a need to put them out small, because the longer they stay in a tank in a laboratory or hatchery, the more they eat each other, he said.
Foy is not discouraged though. He said he felt there are good odds for figuring out the habitat and density needs to lower the mortality rate of very young crab introduced into Trident Basin. The question then is how many will survive over the rest of their juvenile life, so that crab stocks at Kodiak can be enhanced over a long period of time.
Researchers are hoping to enhance the stocks to allow them to reproduce on their own. While they have yet to reach that goal, Foy said results to date suggest that they should keep moving forward with their research.
A federal report on wholesale market profiles for Alaska groundfish and crab fisheries released in May found that snow crab is the most valuable and most abundant of all commercial crab species in Alaska, with 56.8 million pounds harvested with $233.3 million in first wholesale value in 2014.
King crab, both red and blue species caught in Alaska waters, with the greatest concentration in the bering sea, are one of Alaska's most valuable fisheries on a per pound basis, the report said. In 2014, 15.8 million pounds of king crab were harvested in Alaska, representing 10.7 million pounds of production volume worth some $116.7 million in first wholesale value.
Marketing of wild Alaska crab continues to be somewhat impacted by currency exchange rates and competition from illegal, unreported and unregulated fishing in Russia, as well as competition from increased king crab harvests in Argentina and Chile. Still the demand for this delectable, high value seafood remains, providing real incentive to continue the research to assure sustainability of the fishery.