Occurrence of Tarpon, Megalops Atlanticus, Leptocephali in Mississippi Coastal Waters

Tarpon, Megalops atlanticus, larvae (leptocephali) were rare (N=6, pre-metamorphic, 24.0 - 27.8 mm FL) in historic Gulf Coast Research Laboratory fisheries assessment and monitoring collections from Mississippi coastal waters prior to summer/fall 2013 during which time directed sampling produced an unprecedented 40 pre-metamorphic larvae (20.2 - 28.7 mm FL). The specimens were collected July - October using a beam plankton trawl (BPL, 750µm mesh) pulled by hand along the Mississippi Sound mainland shoreline at fixed stations (< 1.5m depth) during daytime. Leptocephali were collected at surface water temperatures and salinities of 24.8 - 34.1^oC and 13.4 - 28.9 ppt., respectively. Preliminary age estimates based on otolith (sagittae) microstructure analysis ranged 28 - 34 days. The source of the leptocephali is unknown, but based on dates of collection, calculated hatch dates, preliminary examination of coastal current patterns within the Mississippi Bight, and recent evidence of spawning capable tarpon from the northern Gulf of Mexico, it is presumed the larvae were dispersed from suspected summer spawning grounds located offshore Mississippi into local estuaries.