{"id":2198,"date":"2008-12-15T12:31:00","date_gmt":"2008-12-15T17:31:00","guid":{"rendered":"http:\/\/ncseagrant.ncsu.edu\/coastwatch\/?page_id=2198"},"modified":"2024-10-01T14:38:52","modified_gmt":"2024-10-01T18:38:52","slug":"investigating-the-mysteries-of-blue-crab-migration","status":"publish","type":"post","link":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/investigating-the-mysteries-of-blue-crab-migration\/","title":{"rendered":"Investigating the Mysteries of Blue Crab Migration"},"content":{"rendered":"\n\n\n\n\n

Fred “Fritz” Bell and deckhands Mark Hastey and Bob Miles set out from Midway Marina in Coinjock at sunrise. Bell’s boat, “Busted,” is stocked with bait for a day of pulling crab pots.<\/p>\n\n\n\n

Heading down the channel into North River, which forms the border between Currituck and Camden counties, the three men start their rhythmic routine: hooking each red-and-green-striped buoy; pulling up the attached pot; shaking the blue crabs into the culling sink; separating them into baskets by size and sex; baiting the pot with fresh menhaden; and throwing the pot back into the water with the buoy trailing behind.<\/p>\n\n\n\n

“I like the freedom out here,” says Hastey, Bell’s brother-in-law and crabbing partner since 1990. “No stop signs. No speed limits.”<\/p>\n\n\n\n

Every basket they fill with an upside-down lid, then set aside for tagging and release back into Currituck Sound as part of a state-funded research project.<\/p>\n\n\n\n

“You can tell the females because they have red nail polish,” Miles says with a chuckle, pointing out the bright red-tipped claws. He also indicates an immature female and the narrow inverted “V” on her belly instead of the Capitol-building shape characteristic of a mature female.<\/p>\n\n\n\n

“She could shed,” Miles says, throwing her back in the water.<\/p>\n\n\n\n

As the boat moves up North River towards fresher water, fewer and fewer females turn up in the pots.<\/p>\n\n\n\n

Mysterious Ways<\/h2>\n\n\n\n

As North Carolina’s most profitable fishery, blue crabs receive a lot of attention from fishermen, researchers and resource managers alike. Yet many details about crab habits remain elusive.<\/p>\n\n\n\n

Most crabbers know to expect a large influx of female blue crabs into fresher water in the late summer to fall, but yearly variations in timing, frequency, and quantity of these migrations make North Carolina blue crab whereabouts anything but predictable.<\/p>\n\n\n\n

“Sometimes crabbers will know where the crabs are and be sitting right on top of them, but the crabs won’t pot” says Marc Turano, North Carolina Sea Grant blue crab specialist and coordinator of the N.C. Blue Crab and Shellfish Research Program<\/a>.<\/p>\n\n\n\n

The Spawning Stock Management section of the current N.C. Blue Crab Fishery Management Plan indicates the need for tagging studies to identify how many crabs are caught during their different life stages, and how females move in relation to where they spawn.<\/p>\n\n\n\n

Bell is one of four commercial crabbers participating in a mature female blue crab tag-and-release study led by Kristina Bridges of Endurance Seafood Company. The blue crab research program is funded by the N.C. General Assembly and administered by Sea Grant. Projects often pair crabbers with scientists or mangers who analyze data.<\/p>\n\n\n\n

This project investigates crabs in Currituck and Albemarle sounds, where data on blue crab migration and catch is especially limited.<\/p>\n\n\n\n

Do all females travel the same direction? Do they travel in a straight line? How much does salinity affect their movement? How fast do they move? No one knows.<\/p>\n\n\n\n

This year, Bridges has noticed a larger catch of hard blue crabs, but only half the normal catch of peeler crabs \u2014 those about to shed their shells \u2014 compared to years past.<\/p>\n\n\n\n

H.L. Bond, another crabber on the project, says lately he hasn’t caught as many females as usual near the mouth of the Perquimans River.<\/p>\n\n\n\n

Researchers don’t know what causes these variations, but some say weather and changes in salinity may be the culprits.<\/p>\n\n\n\n

Mike Mixon, another project participant and commercial crabber for the past 22 years, says the water has been saltier than normal this year.<\/p>\n\n\n\n

Others theorize that crabs move based on tidal cycles, Turano notes.<\/p>\n\n\n\n

Thus, with so many mysteries still to solve, this kind of study may provide important clues.<\/p>\n\n\n\n

As one of three blue crab tagging projects funded in 2008, the Northeast study involves releasing tagged female crabs at selected sites in Albemarle and Currituck sounds and collecting data on location of recapture, number of days at large, and distance traveled for each recaptured crab.<\/p>\n\n\n\n

“It’s interesting just seeing where they end up,” Bell says.<\/p>\n\n\n\n

Tag and Release<\/h2>\n\n\n\n

Each of the crabbers set pots in designated areas once a month from late May through November. Each crabber tagged 150 mature females per month and released them in the following areas:<\/p>\n\n\n\n