KODIAK — Derelict crab pots lost on the bottom of a Kodiak Island bay are capturing significant numbers of its king crab, according to scientists with the National Oceanic and Atmospheric Administration.
Abandoned pots, the traps used by fishermen to catch crab, could be killing 16 to 37 percent of the red king crab with shells longer than 40 millimeters in Womens Bay, they concluded in a study.
Biologists Peter Cummiskey and Eric Munk and analyst Chris Long studied movements of 192 king crabs between 1991 and 2008. They attached acoustic tags and tracked them with hydrophones, the Kodiak Daily Mirror reported.
When crabs stopped moving, Cummiskey and Munk would dive to find them.
They found 32 crabs caught in "ghost" pots, Long told a meeting of the Kodiak/Aleutians Subsistence Regional Advisory Council. Twelve were dead and 20 released alive by the divers.
The divers found 162 pots during the study and cut or wedged them open so they could not continue catching crab, Long said.
Extrapolating the number to determine the total number of pots abandoned would be difficult, Long said, but, "Womens Bay is not very big, and that's a lot of pots."
Pots likely were lost when lines were cut by boat propellers, commercial barge towing bridals or ice, the researchers concluded. They also could be lost if floats tied to the pots sank.
Crabs are drawn to pots even when bait is gone, Cummiskey said by email.
"King crab like to hang out on physical structures, so even a non-baited crab pot can attract crab," Cummiskey said.
Pots are supposed to be equipped with "biodegradable escape mechanisms" that rot quickly and give a king crab a path out of lost pot. Escape rings allowing undersized crabs to escape are required.
Of the pots found by divers, 62 percent did not have biodegradable release mechanisms and many lacked rings.
Increasing awareness of the problem and closing the fishery when ice moves in could cut down on lost pots, Long said.