Red Crab Research

Currently, 100ft commercial vessels from New England harvest red crabs along the deep, narrow, 400m wide swath of the continental shelf within U.S. waters (Fig. 1). However the prospect of increased fishing pressure on the unmanaged New England red crab fishery has raised some concerns about the sustainability of this fishery.

To address these concerns, Drs. Rick Wahle (Bigelow) and Yong Chen (UMaine) have joined forces with red crab harvestor Jon Williams to conduct some of the first population surveys of red crab in over three decades.

Figure 1: Map of the C. quinquedens fishery along the eastern margin of the continental slope in Northwest Atlantic. Pink regions on the map show areas of low red crab density, while red indicates high densities.

With the support of three NOAA programs (Northeast Consortium, Saltonstall-Kennedy, and Sea Grant), this harvestor-scientist team has begun the first season in what they hope will be a three-year project to map the distribution and abundance of red crab. They hope to come to a better understanding of the ecology of the red crab, and to provide fisheries managers and the red crab industry with the information necessary to develop an informed management plan.
Figure 2: Image of red crabs taken during a deep sea survey .
One component of the research project includes deep sea surveys of the red crab. Dr. Wahle and his research assistant, Michael Dunnington, have begun to conduct systematic digital camera surveys of the sea bottom using a benthic sled under tow. They are also using a bottom trawl to provide data on aspects of the crab's biology that the camera survey cannot. Using a mix of state-of-the-art digital imaging technology as well as more traditional sampling methods, the researchers are obtaining the first quantitative information on red crab in decades.

As part of the stock assessment project, researchers are tagging (Figs. 3 & 4) and releasing red crabs to gain information on growth and movement. Fishermen are asked to report the tag number, date of capture, size, and exact location (Lat/Lon or LORAN) of recaptured crabs prior to releasing them.  For more information contact Rick Wahle at 207-633-9612 or Redcrab@bigelow.org.

Figure 3 (left): A blue tag bearing an identification number is inserted into the right side of the carapace; the tag should be retained through a few successive molts, allowing for a comparison between initial and final reported sizes.

Figure 4 (right): Researcher M. Dunnington tagging red crabs.

The camera surveys, bottom trawls, commercial catch, and tagging information are providing details on growth, maturity, and egg production. Dr. Chen will incorporate this life history and abundance information into simulation models of the population yield of red crab under fishing pressure.

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