FISHERY BULLETIN: VOL. 85, NO. 3 



METHODS 



Larvae were collected along three inshore- 

 offshore transects (off Southwest Pass, LA; Cape 

 San Bias, FL; and Galveston, TX) at stations posi- 

 tioned over the 18 m (10 fm), 91 m (50 fm), and 

 183 m (100 fm) isobaths (Fig. 1). Sampling took 

 place on four cruises in December 1979, February 

 1980, December 1980, and February 1981. Collec- 

 tions were made with a Multiple Opening/Closing 

 Net and Environmental Sensing System (MOC- 

 NESS, Wiebe et al. 1976). The MOCNESS con- 

 sisted of nine 505 |xm mesh Nitex'^ plankton nets 

 with mouth openings of 1 m by 1.4 m. Due to 

 equipment problems, only the inshore Southwest 

 Pass station was sampled on the first cruise. 

 Galveston stations were added to the sampling 

 program on the February 1981 cruise. 



MOCNESS nets were deployed in the following 

 manner: Net 1 remained open as the MOCNESS 

 descended from the surface to the deepest depth to 

 be sampled. Nets 2 and 3 sampled at that depth, 

 one at a time, and net 4 opened as the MOCNESS 

 was raised to an intermediate depth, where nets 

 5 and 6 sampled. Net 7 was open while the MOC- 



NESS was brought to the surface, where nets 8 

 and 9 fished. Discrete depth nets generally fished 

 from 2 to 3 minutes before deployment of the next 

 net. Sampling depths were approximately 12, 6, 

 and 1 m at inshore stations and 70, 30, and 1 m at 

 the offshore stations. At each station, MOCNESS 

 casts were made at 0600, 1200, 1800, and 2400 h, 

 with a towing speed of approximately 2 nmi/hour. 

 Sensors on the MOCNESS provided continuous 

 recording of temperature and depth. Two flowme- 

 ters, one mounted on top of the MOCNESS and 

 one within the net opening, were used to calculate 

 the volume of water sampled by each net and to 

 detect net clogging. The mean volume filtered by 

 each discrete depth net was 140 m'^ (SD = 101.2, 

 n = 529). 



The collection of one net at each discrete depth 

 was preserved in 5% buffered formalin-seawater 

 and the collection of the other was preserved in 

 70% ethanol. Formalin-preserved larvae were 

 used in gut content analysis (Govoni et al. 1983), 

 and alcohol-preserved larvae were used in otolith 

 analysis of age and growth (Warlen in prep'*). In 

 the laboratory all fish larvae were removed from 



■^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



4S. M. Warlen. Manuscr. in prep. Southeast Fisheries 

 Center Beaufort Laboratory, National Marine Fisheries Serv- 

 ice, NOAA, Beaufort. NC 28516. 



30° 00' 



- 28° 00' 



26 00' 



- 24° 00' 



96° 00' 94° 00' 92° 00' 90° 00' 88° 00' 86° 00' 84° 00' 



Figure 1. — Location of sampling transects and stations in the northern Gulf of Mexico. 



602 



