Divers collect juvenile red king crabs for field study

Jodi Pirtle with crab collector. Courtesy of J. Pirtle.

A crab collector in the field is colonized by a variety of organisms, including red king crabs. Photo by J. Richar.

University of Alaska Fairbanks divers gathered nearly 200 recently settled juvenile red king crabs, using artificial collectors. The collectors were deployed in May 2010 off Indian Point near Juneau by boat, and retrieved in late July using scuba and other methods. The collectors have an outer skin of tubular plastic netting stuffed with conditioned gillnet or artificial seaweed. It took one week to retrieve and process nearly 60 collectors with the help of University of Alaska Fairbanks graduate students Ben Daly, Miranda Westphal, Jodi Pirtle, and Jon Richar, and laboratory technicians Jaspri Sylvan and Melissa Rhodes-Reese. The purpose of the study was to determine the best method for collecting early juvenile king crabs. Similar studies were conducted in 2008 and 2009 near Juneau to help determine ideal benthic habitat for settling larvae, and to assess variability in numbers of larvae in different locations. The 2010 study refined the collection techniques by comparing scuba and boat retrieval methods using clumped gillnet or artificial seaweed in the collectors. The gillnet and artificial seaweed are attractive to settling king crab post-larvae, which are looking for structural complexity. Both retrieval methods were successful for collecting the crabs, and more crabs were collected using clumped gillnet compared to artificial seaweed. The crabs will be used in future field predation experiments in Juneau.

News Flash is edited by Ben Daly. AKCRRAB is a research and rehabilitation project sponsored by the Alaska Sea Grant College Program, UAF School of Fisheries and Ocean Sciences, NOAA Fisheries, the Alutiiq Pride Shellfish Hatchery, community groups, and industry members. For more information go to http://seagrant.uaf.edu/research/projects/initiatives/king_crab/general.