FISHERY BULLETIN: VOL. 75, NO. 3 



the 17 ichthyoplankton cruises have been pub- 

 lished (Houde and Chitty 1976; Houde et al. 1976). 

 The survey area and its potential sampling sta- 

 tions were illustrated in figure 1 of Houde (1977a, 

 b). Analytical and statistical procedures are based 

 on those discussed by Saville (1964), Ahlstrom 

 (1968), and Smith and Richardson (in press). 



RESULTS AND DISCUSSION 



Occurrence of Eggs and Larvae 



A total of 19,183 scaled sardine eggs and 3,828 

 larvae were collected during the 17 cruises, in 

 which 867 stations were sampled. Scaled sardines 

 composed 59.8% of all clupeid eggs collected and 

 their larvae composed 13.2% of all clupeid larvae. 

 Scaled sardine eggs made up 6.39c of the total 

 fish eggs from the 867 stations and their larvae 

 constituted 2.7% of the total larval fish catch. 



Scaled sardine eggs or larvae were collected on 

 cruises from January through September, but 

 they were most abundant from May through 

 August (Table 1). Stations where they occurred 

 are given in Figure 1. Distribution and abundance 

 of eggs and larvae are illustrated for the May 

 through August cruises (Figures 2-5). Spawning 

 from January to March probably is confined to 

 the southernmost parts of the survey area, since 

 eggs and larvae were collected only at stations 

 south of lat. 26°N on cruises during those months. 



No eggs were collected where depths exceeded 

 30 m (Figure 1). Larval distributions were similar 

 to those for eggs, except for a single anomalous 

 occurrence of larvae at a station on the 200-m 

 depth contour (Figures 1, 3). On cruises CL7405 

 and CL7412 several stations nearer to shore (of 

 only 4-10 m depth) than any on previous cruises 

 were sampled (Figure 5). On cruise CL7412, when 

 intense spawning was taking place, catches of 

 eggs at the nearshore stations exceeded catches 

 at the regular stations. Mean egg abundance 

 under 10 m 2 at positive stations was 1.85 times 

 greater at the nearshore stations than at the reg- 

 ular stations ( 158.93 compared with 85.75). Log 10 

 transformed means were tested in a /-test. 



No. of stations 



Differences were significant (P<0.05). Failure 

 to sample nearshore stations on earlier cruises 

 probably resulted in an underestimate of scaled 

 sardine spawning and also an underestimate of 

 adult biomass if egg distribution during cruise 

 CL7412 was representative of earlier cruises. 



The observed egg and larvae distributions indi- 

 cate that most adults are located where depth 



TABLE 1. — Summarized data on cruises to the eastern Gulf of Mexico, 1971-74, to estimate abundance of scaled sardine eggs and 

 larvae. GE = RV Gerda, 8C = RV Dan Braman, TI = RV Tursiops, 8B = RV Bellows, IS = RV Columbus Iselin, CL = RV Calanus. 



'Positive station is a station at which scaled sardine eggs were collected. 



2 Positive station is a station at which scaled sardine larvae were collected. 



3 An ICITA 1-m plankton net was used on this cruise. On all other cruises a 61 -cm bongo net was used. 



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