Maximizing emigration of young-of-the-year spot (Leiostomus xanthurus) from a South Carolina nursery

Estuaries are among the most productive of all ecosystems and provide critical nursery habitat for many young-of-the-year (YOY) marine fishes.  Along the South Carolina coast, former ricefield impoundments in estuarine areas are managed as waterfowl habitat.  Marine fishes that enter these structures during water-level manipulation become trapped and suffer high mortality.  Because these fish cannot emigrate to coastal waters to complete their life cycles, the impoundments act as sinks.  We compared effects of impoundments and other stressors such as predation and drought on YOY spot (Leiostomus xanthurus) emigration from the Combahee River, SC.  We also identified management options that would maximize YOY spot emigration.  We used structured decision analysis via a Bayesian belief network (BBN) to evaluate five management decisions: implement fishing regulations for spot, close impoundments while YOY spot are abundant in the river, change water-level manipulation to improve egress from impoundments, breach all impoundments, or maintain status quo.  The optimal management decision was to change the water-level manipulation strategy to increase egress from impoundments.   The results of this model can be used adaptively for impoundment management along the Combahee River and can be modified for other estuarine areas or fish species.