Pink or spotted (Penaeus duorarum) , brown (P. aztecus) , and white (P. setiferus) shrimp, marked with biological stains and fluorescent pigments, were released in nursery areas tributary to the Core Sound and Lower Cape Fear River estuaries in Nor·th Carolina to obtain information concerning population dynamics including movement and migration patterns. A combined total of 26,989 pink, brown, and white shrimp was marked and released from April to October, 1966. Of these, 1,671 or 6.2% were returned. The combined average interval between release and recapture was 17.5 days, and the average distance traveled was 0.5 miles per day. Data indicated that size distribution "levels of equilibrium" were reached in individual nursery areas, whereby the size frequency modes increased to characteristic levels and subsequently remained at these levels during the study of each species. With few exceptions, all "inside" movement was toward waters of higher salinity. A southward coastwise migration was evident throughout the periods of study and involved movement to St. Augustine, Florida.