Ecology and Growth of Juvenile Tarpon, Megalops Atlanticus, in a Georgia Salt Marsh

Juvenile tarpon were found in both still and flowing dark water in marsh pools and creeks on Sapelo Island, Georgia. These fish grew approximately three centimeters per month. Two populations of juveniles were found during 1964: a resident population and a second one driven shoreward from the Gulf Stream by hurricane Dora. Tarpon from the second population grew approximately half as fast as those of the first population. Fish in the second influx encountered lower temperatures and less abundant food earlier in their existence than did those of the first population. The latter were probably the only ones to survive to migrate to warmer waters late in November.

Postlarval tarpon are strictly carnivorous and they are predominantly piscivorous. The principal food varies with relative availability of different food organisms. The size of the food consumed is directly related to the size of the tarpon. Juveniles less than 125 mm in standard length consumed large numbers of ostracods; shrimps (Palaemonetes spp.) were eaten by tarpon longer than 76 mm in standard length. Fishes, mainly Gambusia affinis, were eaten by tarpon of all sizes sampled. Piscivorous birds appear to be the principal predators of juvenile individuals of Megalops.