Commercial Tanner crab harvesters for the Kodiak, Alaska district will have a 300,000-pound guideline harvest level (GHL) for the eastside section and 100,000 pounds for the southeast section for the 2020 fishery opening on Jan. 15.
The GHLs are based on analysis of the 2019 Tanner crab survey. They were announced by the Alaska Department of Fish and Game’s (ADF&G) Kodiak office on Oct. 31.
ADF&G reminds harvesters that because this year’s Kodiak District Tanner crab GHL is less than 2,000,000 pounds, the regulatory gear limit is 20 pots per vessel.
The southwest, south mainland, north mainland, westside and northeast sections of the Kodiak district are closed to Tanner crab harvests this year.
“We are fishing on the end of a large cohort of crab,” said Natura Richardson, assistant area management biologist for ADF&G in Kodiak, who acknowledged that the catch opportunity was down from a year earlier. “We saw a large cohort of crab first enter (the fishery) in 2013. Those crabs got to legal size in 2018,” she explained.
Richardson noted that there were also a large number of juvenile Tanner crab in last year’s survey and that those crab were seen again in the 2019 survey, “so they are tracking well; they are surviving at a higher rate and growing a little faster than the previous cohort,” she said.
“I don’t think that it is a small coincidence that there are not a lot of cod in the water,” she added. “Cod eat crab and there are not a lot of cod out there.” The decline of cod in both the Gulf of Alaska and the Bering Sea has been dramatic over the past two years.
The 2019 GHL for the eastside section is 500,000 pounds, with another 115,000 pounds for the southeast section. In 2018, the GHL was 260,000 pounds for the eastside and 140,000 pounds for the southwest section. Federal biologists have also noted that the relief in predation from Pacific cod may be a factor in the increased abundance of Tanner crab in the Gulf of Alaska. Pacific cod tend to prey on one and two-year-old Tanner crab.
In the wake of the cod crash over two years ago, Tanner crab coming into the fishery now may have benefited from that crash, and if that is true, the fisheries managers can anticipate seeing more Tanner crab entering the fishery. Tanner crab are also prey for halibut, sculpins and other flatfish, including arrowtooth flounder.
While the relationship of ocean temperatures to the health of young Tanner crab has not been specifically studied, the expectation is that they would grow faster in warming waters as long as they have sufficient food, given success in recruitment over the past few years. The young crab, living on the bottom of the ocean, feed on small organisms on the surface of the mud.