NORTH 

 CAROLINA 



LOOKOUT 



cape fear/ ATLANTIC OCEAN 



.-- 1 --"* — 



V 



'*-.«-..; 



34° 30* 



34° 00* 



33° 30* 



1 



1 



1 



78° 00' 



77° 30' 



77° 00' 



76° 30' 



76° 00' 



FIGURE 1.— Location of ichthyoplankton stations in Onslow Bay and Newport River estuary, N.C., sampled October 1972-April 1974 (dots), 

 October 1972-September 1973 (circles), and October 1973-April 1974 (squares). Sampling stations are grouped according to offshore dis- 

 tance and water depth: Zone 0, Newport River estuary; zones 1-3, inshore to ocean; zones 4-6, offshore to ocean. 



leaving 16 stations to be sampled the second year. 

 Because the Onslow Bay had limited range and had to 

 be returned to port each night, about 5 d/mo were re- 

 quired to run all stations. Samples were taken be- 

 tween 0800 and 1700 h. Tows were not stratified by 

 tidal cycle; all collections were assumed completely 

 random. During the 19 mo, sampling was missed 

 completely for 1 mo and was only partially completed 

 during six other months, due either to mechanical 

 failure of the vessel or winch or to adverse 

 weather. 



Samples were preserved in 5% buffered Formalin. 

 Larvae and eggs were removed with the aid of a dis- 

 secting microscope. Larvae were identified to the 

 lowest determinable taxon, counted, and measured 

 to the nearest 0.1 mm standard length (SL) or 

 notochord length, depending on stage of develop- 

 ment. All measurements denote larval length. For 

 large catches, 50 larvae/subsample were measured. 



Larvae were categorized by length groups according 

 to the developmental stages as defined by Fruge and 

 Truesdale (1978) and Powell and Gordy (1980). Pre- 

 flexion larvae measured 2.0-4.0 mm SL, flexion 4.1- 

 5.0 mm, and postflexion >5.0 mm. Larval data from 

 the 0.333 and 0.505 mm mesh nets were combined 

 for each station within a month to provide a better 

 synoptic profile of each station, since there is less ex- 

 trusion of larvae <4 mm from the 0.333 mm mesh net 

 and higher catches of larvae > 1 mm in the 0.505 mm 

 mesh net. Counts were adjusted to a standard catch 

 (Smith and Richardson 1977:36) at each station by 

 the following formula: 



SHF = 



100D 

 V 



where SHF 

 V 



standard haul factor 

 volume of water strained (m 3 ) 



406 



