In the wake of a second experimental scale release of hatchery reared red king crabs into Kodiak’s Trident Basin, NOAA scientists are working on the analysis of data to determine how release time and crab size affect the survival of the crab.
The key is to determine when and at what density and into what habitat to release these hatchery reared crab to assure their best chance of survival, says Bob Foy, who oversees these and other crab studies at NOAA’s Alaska Fisheries Science Center at Kodiak. The data will help scientists determine optimum size of crab, when to release them and the best habitat for their survival from predation and ability to feed. Crab employed for this latest release were hatched about three months prior to release.
During the second year of this major study some 15,000 juvenile king crab were released into Trident Basin, and plans are to release between 50,000 to 100,000 crabs next year at three different locations, Foy said.
The 2015 experiment was built on a 2014 release in Trident Basin, which examined effects of stocking density on post-release survival. The 2014 release demonstrated that crabs could be released at a high density – up to 75 per square meter – without substantial increases in mortality.
Red king crab juveniles are highly cannibalistic in laboratory or hatchery settings, so the longer they are held before release the fewer crabs survive to be released. The 2015 study also suggested that predation rates in the field are higher in summer than in fall.
The experiments collectively represent a significant step forward for the Alaska King Crab Research, Rehabilitation and Biology program. The work is sponsored by AFSC, the University of Alaska Fairbanks School of Fisheries and Ocean Sciences, the Alutiiq Pride Shellfish Hatchery, community groups, industry members, and the Alaska Sea Grant program.