Fishermen's News - The Advocate for the Commercial Fisherman

Crab Tagging

 

July 1, 2019

Tags will transmit water temperature and the identification number of the crab to the saildrone receiver. Photo courtesy of NOAA.

NOAA Fisheries is teaming up with the bering sea Fisheries Research Foundation in a research program to track the movement of adult male red king crabs in Bristol Bay using an unmanned surface drone made by Saildrone, Inc.

NOAA researchers hope their findings will provide information crucial to keeping red king crab sustainable as climate change continues, including which habitats are essential for Bristol Bay red king crab in different seasons and whether current protected areas are effective.

The federal fisheries scientists plan to work with harvesters in June to tag crabs with acoustic devices that transmit an identification number and a bottom temperature. Tagging is timed right after the NOAA Fisheries summer survey, so researchers will be able to target where crabs are most abundant. NOAA Fisheries said the team will deploy a sail drone equipped with an acoustic receiver in October and again in April 2020 to relocate the tagged crabs.

"Managers need to understand where crabs go in different seasons, and what habitats are essential, to set effective rules for fishing," said Leah Zacher, the NOAA Fisheries scientist leading the project. "Everyone benefits from increasing our knowledge of crab distributions.

"So little is known about where crabs are and how they move," said Scott Goodman, president of Natural Resources Consultants, Inc, in Seattle, and executive director of BSFRF. "We have only snapshots from summer surveys. This research will fill in the life history gaps to better inform the management of red king crab as both target and bycatch.

"This technology will collect many data points for each crab released. It is a new paradigm for tag release and recovery studies," he said.

The nonprofit BSFRF that Scott heads has as its goal assisting to determine and develop the best scientific approach for gathering information for management of the bering sea crab fisheries.

Since 2005, The BSFRF has participated and led cooperative research with industry, the Alaska Department of Fish and Game, and the National Marine Fisheries Service, to improve the science used in bering sea crab fisheries management. More than 95 percent of BSFRF funding comes from private industry supplemented occasionally with grants. The BSFRF is funding the saildrone being used to track the tagged crab.

"We know where crabs are in the summer from annual NOAA Fisheries sureys, but there is little information for the rest of the year," Zacher said. "We will relocate the crabs in the fall to understand how crabs move onto the fishing grounds, and in the spring to determine their locations when they are vulnerable to being caught as bycatch in trawl fisheries."

"We have a huge area to search for moving targets in an ever-changing environment. Traditional tag and recover methods require an enormous investment of time. You are dependent on the crabs being caught in a fishery and the tags returned-you never know if or when the tags will come back. Tracking crabs acoustically from a manned vessel would be unfeasibly expensive," Zacher explained. "With a saildrone we can cover huge areas cost-effectively, at the times when we need data."

Temperature information transmitted by each crab tag will help determine temperature influences on crab movement. Researchers will also compare crab locations with sediment maps to identify characteristics of essential habitat.

Researchers also want to know if protected areas are actually protecting crabs.

"The red king crab savings area is closed to trawling to provide a protected habitat, but the area was initially set based on limited information, and managers need to know if and when red king crabs are moving through and using those areas to know if they are effective, Zacher said.

The Alaska Fisheries Science Center planned to begin posting reports on its research from the field in June on the AFSC Science Blog at fisheries.noaa.gov.

 
 

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