Thursday, April 21, 2011

Building a case for changes in management

Blue crab fisheries have been around for decades and are among the top fisheries by weight of crabs landed and dollar value in many Southeast US states. This belies the fact that many of the fisheries have declined in recent decades. The declines are clearly visible in the following graphs showing landings of hard blue crabs by year since 1950 (derived from NMFS Commercial Landings Data).


North Carolina




South Carolina






Georgia




Florida (East Coast only)


There are a variety of factors driving these downward trends which may include overfishing, declining fishing effort, reduced prices due to competition with imported crab meat, rising costs (for fuel, dock space, property taxes, etc.), loss of crab processing faclilities, loss of habitat, degraded water quality, changes in how fisheries are managed and landings are reported, and others. It is incredibly difficult to interpret declines in fishery landings due to the complex factors that affect fishing. Regardless of whether these declines are due to a reduction in the crab population or a decline in the fishing industry, the decline of blue crab fisheries is bad for coastal communities because it represents a loss of economic opportunity, the loss of a local food source, and, if it is populations that are declining, the loss of an important predator, scavenger and food source in coastal rivers and marshes and the continental shelf.

Blue crab fisheries are managed individually by each state. Although fishing regulations have varied somewhat from state to state, these regulations often include minimum size limits, gear restrictions (type and number of fishing gear; i.e. crab pots, trotlines, trawls, etc.), bans on harvesting sponge (egg-bearing) crabs, etc. Although these regulations may help protect crab populations, they have clearly not been successful in preventing declines in crab fisheries as evidenced by the above figures. Therefore, I argue that we must evaluate additional or different strategies for managing crab fisheries in order to sustain both healthy crab fisheries and healthy crab populations (without which there can be no fisheries).

2 comments:

  1. I wonder if a more comprehensive multi-state management plan would work? I am pretty sure I saw a talk at Shellfish about tagging blue crabs and a few from Chesapeake tributaries ended up North Carolina. And given their larval life stage, maybe this isn't a species that should be treated as separate stocks by state?

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  2. Thanks for your comment John. You are correct that tagged crabs from one state sometimes are sometimes caught in nearby states and that there likely is larval exchange among states as well. The idea of multi-state stock management is likely to be controversial, but it does have precedent in the management of blue crab stocks in the Chesapeake Bay. These stocks are cooperatively managed by MD, VA, and the Potomac River Fisheries Commission. Defining individual stocks has not been simple because blue crab population genetics has been difficult to sort out, so the scientific basis for multi-state crab stocks is currently limited. I'll work to get a post on this in the near future.

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