Decision rules of blue crab (Callinectes sapidus) movement in wind-driven systems
Abstract
Blue crabs (Callinectes sapidus) are the most economically valuable fishery in North
Carolina, and the commercial harvest is mainly from the Albemarle-Pamlico Estuarine
System (APES). Because of small inlets which restrict ocean tidal forcing in addition
to large expanses of shallow water, circulation in the APES is primarily wind-driven.
While much is known about how crabs move in tidally-dominated systems where movements
are based upon selective tidal-stream transport, crab movements in wind-driven systems,
and their response to environmental factors, remain poorly understood. This study
aims to increase understanding of environmental controls on blue crab movements in
order to inform management of crab resources in wind-driven systems.
We studied crab movements in Lake Mattamuskeet National Wildlife Refuge, a 40,000-acre
shallow, wind-driven system within the APES. During October 2014, free ranging crabs
were tracked using radio frequency identification (RFID) tags and an antenna array
deployed along the Central Canal connecting the lake to Pamlico Sound. Colocated and
simultaneous meteorological and physical oceanographic data were collected to understand
environmental drivers that may affect crab movements. Analyses of these data indicate:
1) a significant net export of blue crabs from the lake to the sound; the drivers
of that export remain unclear; 2) crab movements coincided with the direction of water
flow in the canal, and 3) at small-scales, crabs were able to move against the water
flow. These results suggest that there is a fall migration, during which crabs move
from the lake to the sound, and at a relatively constant rate that is slower than
the mean water flow.
If crabs are to move out of the lake at this time it is essential to open water control
structures in order to facilitate migration. This is particularly important for the
females, who because of their large size may contribute disproportionately large amounts
of larvae to the Pamlico Sound broodstock. Crabs in the larger fishery may also move
toward higher salinity water if they behave similarly to those studied here.
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https://hdl.handle.net/10161/9693Citation
Chen, Julia (2015). Decision rules of blue crab (Callinectes sapidus) movement in wind-driven systems.
Master's project, Duke University. Retrieved from https://hdl.handle.net/10161/9693.Collections
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