THE DISTRIBUTION OF SUMMER FLOUNDER, 



PARALICHTHYS DENTATUS, EGGS AND LARVAE ON 



THE CONTINENTAL SHELF BETWEEN 



CAPE COD AND CAPE LOOKOUT, 1965-66 



W. G. Smithi 



ABSTRACT 



Eggs and larvae of summer flounder, Panilichthys deniatus, were collected with Gulf V 

 plankton nets between Cape Cod, Mass., and Cape Lookout, N.C., during a 1-year survey 

 of continental shelf waters. The most productive spawning grounds were located off 

 New York and New Jersey. Spawning began in northern parts of the survey area, pro- 

 gressed southward with the season, and ended off Cape Lookout. We collected eggs 

 north of Chesapeake Bay from September to December and south of the Bay from 

 November to February, and larvae north of Chesapeake Bay from September to February 

 and south of the Bay from November to May. Most spawning occurred at temperatures 

 between 12° and 19 °C, but the pelagic eggs were caught at mean temperatures from 9.1° to 

 22.9°C, and the larvae from 0° to 23.1 °C. 



Fishery scientists generally agree that the 

 shallow, protected waters of bays, rivers, and 

 sounds along our eastern seaboard provide 

 essential habitat for many marine fishes. The 

 occurrence of juvenile fishes in estuaries has 

 led biologists to conclude that a major role of 

 the estuarine zone is its function as a sanctuary 

 or nursery ground for young fishes, many of 

 which are spawned at sea. In 1965, the Sandy 

 Hook Laboratory at Highlands, N.J., began a 

 study to elucidate the degree of estuarine 

 dependence of young fishes by studying their 

 distributions from egg through juvenile stages. 

 Impetus for the study resulted from the accel- 

 erated degradation of the estuarine zone and 

 a concurrent decline in some of our most 

 valuable coastal fishery yields. 



We began our program with a 1-year survey 

 of the continental shelf between Cape Cod, Mass., 

 and Cape Lookout, N.C., to determine the 

 duration of spawning, define the areas of 

 spawning, and trace the dispersal of pelagic 

 eggs and larvae of all marine sport fishes that 

 we caught. This report describes the offshore 

 distribution of eggs and larvae of the summer 



' Middle Atlantic Coastal Fisheries Center, National 

 Marine Fisheries Service, NOAA, Highlands, NJ 07732. 



Manuscript accepted October 1972. 



FISHERY BULLETIN: VOL. 71, NO. 2, 1973. 



flounder, Paralichthys dentatus, a highly prized 

 catch for both sport and commercial fishermen. 

 The life history of summer flounder is under- 

 stood only in broad outline. The geographic 

 range of the species encompasses estuarine 

 and continental shelf waters from Maine to 

 Florida (Gutherz, 1967). Within this range, 

 the species' population structure remains to be 

 determined. Migratory habits of summer floun- 

 der in the Middle Atlantic Bight have been 

 outlined from seasonal changes in the location 

 of commercial and sport catches. From the 

 returns of tagged fish, Poole (1962) and Muraw- 

 ski (1970) added support to the general con- 

 cept that yearly movements of summer flounder 

 are not extensive. The adults migrate shore- 

 ward in spring from wintering grounds near 

 the edge of the continental shelf. They summer 

 in shallow coastal waters and adjacent estu- 

 aries and, in the fall, again move offshore. 

 Both Poole and Murawski noted the strong 

 tendency of adult fish to return in subsequent 

 years to the area where they had been tagged. 

 Shortly after the adults begin their fall migra- 

 tion, they begin to spawn, presumably on or near 

 the bottom. Eggs and early larval stages have 

 been found only at sea, and young-of-the-year 

 juveniles only in or near the mouths of estuaries. 



527 



