Ditty et al.: A redescription of Chaetodipterus faber larvae 



263 



tic spadefish were determined from collections taken 

 primarily during Southeast Area Monitoring and 

 Assessment Program (SEAMAP) ichthyoplankton 

 surveys of the Gulf between 1982 and 1986 

 (SEAMAP 2 ). These years represent the first time 

 interval for which a complete set of data were cur- 

 rently available. Latitude 24°30' N was the south- 

 ern boundary of our study area in the eastern Gulf, 

 a cutoff which approximates the continental shelf 

 break off the southern tip of Florida. Latitude 26°00' 

 N was the southern boundary of the central and 

 western Gulf. These coordinates approximate the 

 U.S. Exclusive Economic Zone (EEZ (/Fishery Con- 

 servation Zone (FCZ). 



Standard ichthyoplankton survey techniques as 

 outlined by Smith and Richardson (1977) were em- 

 ployed in data collection. Stations sampled by Na- 

 tional Marine Fisheries Service (NMFS) vessels 

 were arranged in a systematic grid of about 55-km 

 intervals. NMFS vessels primarily sampled waters 

 >10 m deep. Each cooperating state had its own 

 sampling grid and primarily sampled their coastal 

 waters. Hauls were continuous and made with a 60- 

 cm bongo net (0.333-mm mesh) towed obliquely 

 from within 5 m of the bottom or from a maximum 

 depth of 200 m. A flowmeter was mounted in the 

 mouth of each net to estimate volume of water fil- 

 tered. Ship speed was about 0.75 m/sec; net retrieval 

 was 20 m/min. At stations <95 m deep, tow retrieval 

 was modified to extend a minimum of 10 minutes 

 in clear water or 5 minutes in turbid water. Tows 

 were made during both day and night depending on 

 when the ship occupied the station. Overall, 1,823 



2 SEAMAP. 1983-1987. (plankton). ASCII characters. Data for 

 1982-1986. Fisheries-independent survey data/National Ma- 

 rine Fisheries Service, Southeast Fisheries Center: Gulf States 

 Marine Fisheries Commission, Ocean Springs, MS (producer). 



bongo net tows were made between 1982 and 1986. 

 The SEAMAP effort between 1982 and 1984 also 

 involved the collection and processing of 814 neus- 

 ton samples taken with an unmetered 1x2 m net 

 (0.947-mm mesh) towed at the surface for 10 min- 

 utes at each station. SEAMAP sampling during 

 April and May was conducted primarily off the con- 

 tinental shelf; sampling during March, and from 

 June through December, was conducted primarily 

 over the shelf at stations <180 m deep. Additional 

 information on the spatial and temporal coverage of 

 SEAMAP plankton surveys is found in Stuntz et al. 

 (1985), Thompson and Bane (1986, a and b), Thomp- 

 son et al. (1988), and Sanders et al. (1990). Atlantic 

 spadefish larvae were also obtained from surface- 

 towed 1x2 m neuston net collections (0.947-mm 

 mesh, 71 samples) made by the National Marine 

 Fisheries Service (NMFS, Panama City, Florida) 

 during August 1988. These NMFS collections were 

 associated with riverine/oceanic frontal zones off the 

 Mississippi River delta. Frontal zones near the delta 

 were not sampled during either June or July. 



A detailed examination of Atlantic spadefish lar- 

 vae was made to describe developmental morphol- 

 ogy. Body measurements were made on 21 Atlantic 

 spadefish larvae between 1.9 and 12.5 mm (Table 1) 

 and follow Hubbs and Lagler (1958) and Richardson 

 and Laroche (1979). Measurements were made to 

 the nearest 0.1 mm with an ocular micrometer in a 

 dissecting microscope. We follow Leis and Trnski's 

 (1989) criteria for defining length of preopercular 

 spines, body depth, head length, eye diameter, and 

 the eye diameter/head length ratio. We consider 

 notochord length in preflexion and flexion larvae 

 synonymous with SL in postflexion larvae and re- 

 port all lengths as SL unless otherwise noted. Speci- 

 mens were field-fixed in 10% formalin and later 

 transferred to 70% ethyl alcohol. Terminology for 



