Identification of Forage Fish in Estuarine Systems Using Qualitative and Quantitative Criteria

There has been an increased focus on identifying important forage fish and managing them at levels that prevent ecosystem overfishing.  Several groups (e.g. Lenfest, Mid-Atlantic Fishery Management Council) have established qualitative characteristics of forage fish.   In general, they define forage fish as being short-lived, forming large schools, and providing the main link between plankton and higher trophic levels.  These characteristics are derived from meta-analyses of food habits data predominately from oceanic ecosystems and may not apply to estuarine environments.  We test this hypothesis by comparing the identification of forage fish using the qualitative characteristics described above and a recently published quantitative approach, Supportive Role to Fisheries ecosystems (SURF; Plagányi and Essington, 2014).  Data used to identify estuarine forage fish are from a multispecies food habits data set from Pamlico Sound Estuary, North Carolina that examined the diets of 25 predator species (n= 16,979 stomachs).  The qualitative and quantitative approaches overlapped in identification for some forage fish but the SURF approach identified estuarine forage fish the qualitative approach did not.  If current qualitative approaches are used by fisheries managers in estuarine environments, important forage species may be overlooked and their harvest set at levels leading to ecosystem overfishing.