Maryland Derelict Fishing Gear Benthic Survey

This project was conducted by the NOAA Chesapeake Bay Office to support its multiyear study of the effects of derelict fishing gear on habitat and fishery resources in the Chesapeake Bay. The Derelict Fishing Gear Study was funded in part by the NOAA Marine Debris Program.

What's Going On?

Derelict fishing gear, including lost or abandoned nets and crab traps, can create safety, nuisance, environmental, and economic impacts in coastal waters. The Chesapeake Bay blue crab fishery—the nation's largest—uses metal traps as the primary method of harvest.

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Standard commercial crab trap

Conservative estimates suggest that more than 300,000 crab traps are deployed in the Bay on a typical day during the summer. Information from the Chesapeake Bay and around the United States suggests that every year, each commercial fishermen may lose from 20% to 30% of their traps for a variety of reasons.

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Commercial crabber setting traps

Traps are set with a line attached to a marker buoy or 'float' to identify ownership and facilitate retrieval. Crab traps become 'derelict' after their float line is severed by vessel propellers, chafed through due to wave action, or tangled up on the trap itself as it is rolled by strong currents and waves. Without floats, watermen are unable to find their traps to retrieve them and harvest the contents. The lost traps may then be "ghost fishing"—trapping, wounding, and eventually killing blue crabs, fish, birds, reptiles, and aquatic mammals; degrading marine ecosystems and sensitive habitats; causing economic hardship for working watermen, seafood wholesalers, the restaurant industry, and consumers; and forming hazards to recreational, commercial, and military navigation.

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Severed crab trap float line

 

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Recovered derelict trap with fish and crabs

 

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Blue crab and pumpkinseed in derelict trap

 

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Trapped white perch and perch skeleton

Acoustic Seafloor Mapping Project Targets Derelict Fishing Gear

The NOAA Chesapeake Bay Office, in collaboration with a number of federal, state, and academic partners including the Maryland Department of Natural Resources, Virginia Marine Resources Commission, Virginia Institute of Marine Science, and the NOAA Marine Debris Pogram, is leading a two-part evaluation of the potential effects of derelict crab traps on habitat and fishery resources in the Chesapeake Bay. First, NOAA used side-scan sonar technology and a stratified random survey design based on fishing effort to locate, map, and count derelict traps on the bottom of the Bay. The sonar surveys were conducted from late February through late March 2007, during the period when harvest was closed to the commercial fishery (December 15 to March 31) to ensure that all traps encountered were derelict.

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Areas of differing fishing effort in Maryland waters


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Survey transect from stratified random survey

 

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Example of side-scan sonar showing derelict trap targets as cubes on the bottom

 

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Retrieval of derelict traps confirms sonar identification

What Has Been Learned?

The survey results were used to estimate that more than 85,000 actively fishing ghost fishing crab traps were on the bottom of the Maryland portion of the Chesapeake Bay at the time of the survey. Surveys in Virginia indicate that at least 35,000 derelict traps are ghost fishing the waters of the Virginia portion of the Chesapeake and its tributaries. These estimates were then used in a field experiement conducted by the NOAA Chesapeake Bay Office to assess the impact on blue crab and bycatch species populations and help resource managers take appropriate action.

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