Table 1. —Cruise schedule and sequence of sampling transects during R. V. 



Dolphin ichthyoplankton survey, 1966-66. Sampling interruptions in excess 



of 48 hr arc shown, whether or not the sampling sequence was affected. 



D-66-12 Sept. 2B-0ct. 6, 1966 M, N, L to F, E-1 to -3, D-1 to -3 



Oct. 11-15, 1966 t.-A to -8, F-8 to ^, C to A 



Oct. 20, 1966 P 



D-66-14 Nov. 9-14, 1966 E to J (except F-7, E-8) 



Nov. 15-19, 1966 P to K, F-7, E-8 



Dec. 1-4, 1966 D to A 



water forms below the thermocline from New York to as far 

 south as Virginia (Bigelow 1933; Ketchum and Corwin 1964). 

 The cell's pronounced effect on the distribution and 

 movements of several summer spawning fishes is reflected 

 in the patterns of their egg and larval distributions. Late 

 summer and fall storms usually break down the thermal 

 stratification, and water temperatures cool rapidly there- 

 after. By winter, the water column is isothermal, except 

 near the outer edge of the shelf where temperatures are 

 usually warmer near the bottom than at the surface. 



Salinity throughout the bight seldom reaches 35%o, and it 

 is usually less than 30%o at the mouths of the major 

 estuaries. Whereas water temperatures often seem related 

 to the spawning habits of some species, we were unable to 

 relate our salinity observations to spawning or the 

 distribution of flatfish larvae. 



Circulation within the bight has been studied largely by 

 the release and return of drift devices such as bottles and 

 seabed drifters. Nontidal drift is generally west to 

 southwest but it changes seasonally, and surface and 

 subsurface currents sometimes flow in opposite directions 

 (Bumpus and Lauzier 1965; Norcross and Stanley 1967). 

 Wind and runoff are the external forces most responsible for 

 nontidal water movement in the bight. The intrusion of high 

 salinity ocean water into the bight is poorly understood, but 



it probably occurs through exchange of shelf and slope water 

 along the outer edge of the shelf (Bumpus 1973). Much of 

 the coastal water turns seaward near Cape Hatteras and 

 becomes entrained in the Gulf Stream (Norcross and 

 Harrison 1967). 



The Gulf Stream passes within 22 km of Cape Hatteras. 

 As the stream meanders northward, it acts as a 

 transport vehicle for larvae spawned throughout the 

 warm-temperate and tropical waters of the western North 

 Atlantic. Thus, it is difficult to predict the origin of larval 

 fishes caught off the North Carolina capes. Many of the 

 larvae we caught off North Carolina, and some caught as far 

 north as New York, probably originated somewhere off our 

 southeast coast and were subsequently transported north- 

 ward by the stream. 



The literature falls far short of providing the information 

 needed to describe adequately how environmental factors 

 influence spawning, and the subsequent distribution of eggs 

 and larvae in the bight. Although our survey was not 

 designed to permit such detailed analyses, some of the 

 distributional patterns of larvae can be related to circulation 

 trends; and the onset, extent, and duration of spawning 

 often can be associated with rather narrow ranges of 

 temperature. These associations are noted throughout the 

 text. 



