Identification of the Spawning Grounds and Offshore Migration Corridor Used by the North Carolina Stock of Southern Flounder. Grant uri icon

abstract

  • Southern flounder (Paralichthys lethostigma) is an economically important species throughout its range, but this fish is overfished in North Carolina and throughout the southeastern USA. There is uncertainty as to the source of recruits to the fished population in North Carolina estuaries. Adults are thought to migrate from estuaries through inlets to offshore spawning areas. Conventional tag returns show these fish move southward into the Atlantic from North Carolina to South Carolina, Georgia and northeast Florida. Although current management decisions are made at the state level, fishers in North Carolina and states southward to Florida are likely catching fish from the same population, representing a single stock. Offshore spawning grounds have not been identified for the southern flounder populations in any state. Our objectives are to: (1) Determine the timing of offshore migration and inshore immigration by acoustically tagging southern flounder in North Carolina and monitoring when they pass through an acoustic gate spanning all inlets in Pamlico Sound; (2) Track offshore migrations of tagged flounder and locate possible spawning grounds by using an offshore acoustic curtain and an autonomous vehicle (wave glider with telemetry receiver); (3) Conduct ichthyoplankton surveys at potential spawning sites and use DNA barcoding to determine if southern flounder eggs are found; (4) Use otolith microchemistry to identify the natal habitat of adult southern flounder caught in North Carolina; (5) Back calculate the location of potential spawning habitats of southern flounder by aging larval flounder caught shortly after ingress into an estuary and using a hydrodynamic model to identify larval dispersal pathways. This multi-pronged approach for identifying spawning grounds of southern flounder will benefit fisheries managers and fishers by determining what is the appropriate spatial scale for management of this population and will allow potential protection of spawning grounds if they occur at a discrete site.

date/time interval

  • January 2020 - June 2024