Mapping & Surveying: Marine Debris/Derelict Crab Pots
Fish continue to be caught in derelict
"ghost" crab pots
Derelict "ghost" crab pots are those blue crab pots lost either through
accident (cutting of the buoy float line by boat propellers), storm
events, or abandoned. These pots continue to capture blue crabs as well as
other marine organisms. The continued fishing of these pots can have a
significant impact on the recreational and commercial blue crab fishery
and the economy of local communities. For example, the Gulf States Marine
Fisheries Commission has estimated blue crab ghost fishery losses as high
as 4 to 10 million crabs a year in Louisiana.
Preliminary results of pilot surveys funded by the Marine Debris Program
in 2005 successfully demonstrated the feasibility of using side scan sonar
and bathymetric surveys to identify and geospatially position derelict
crab pots in the Maryland and Virginia portions of the Bay.
This project investigates blue crab mortality rates associated with ghost
pots in the Chesapeake Bay including the 'self-baiting' phenomenon of
derelict traps. Blue crab escape potential from traps of various ages and
conditions is investigated in the laboratory. Crabs were placed in
traps in an enclosed system to estimate blue crab escape ratios by trap
K.J. Havens, D.M. Bilkovic, D Stanhope, K Angstadt, and C Hershner. December 2006. Derelict Blue Crab Trap impacts on marine fisheries in the lower York River, Virginia. Final Report to NOAA Chesapeake Bay Program Office. Center for Coastal Resources Management, Virginia Institute of Marine Science.
C. Hershner, K.J. Havens, D.M. Bilkovic, D. Stanhope, K. Angstadt. December 2005 and March 2006. Marine Debris Survey in Virginia Interim Report for NOAA/NMFS Grant.
New and ongoing projects Funded by National Fish and Wildlife Foundation
1) Effects of Ghost Crab Pots in the Chesapeake (VA) - Dec 2006-Nov 2007
Summary: This project resulted in an assessment of derelict blue crab trap catch efficiency and mortality rates. Traps in high salinity areas become less efficient in trapping organisms after 2 years. Traps in brackish areas remain efficient in trapping organisms beyond two years. Once crabs enter the top chamber of a trap, escape rates drop significantly and mortality over time is high.
K. J. Havens, D.M. Bilkovic, D. Stanhope, K. Angstadt, and C. Hershner. Derelict Blue Crab Trap impacts on marine fisheries in the lower York River, Virginia. N. Am J. of Fish. Manag. In Press.
2) Experimental and field efforts to assess the effectiveness of gear modification for blue crab pots to reduce crab and by-catch mortality by derelict crab pots. Mar 2007-Mar 2008.
Project Objectives: This project will test gear modifications to reduce the effectiveness of derelict traps. Modifications to be tested include biodegradable panels, ‘memory plastic’ and/or ‘rebound rubber’ coupled with ‘rot cord’ to provide an escape mechanism for marine fauna trapped by derelict ‘ghost’ crab pots. Quantitative data will be collected on the effectiveness of the gear modifications on blue crab and by-catch mortality. An analysis of the additional cost associated with the gear modification and a summary of other state regulations regarding derelict blue crab pots will be conducted.
See related article on derelict crabpots in the Bay Journal