HOUDE: ABUNDANCE AND POTENTIAL YIELD OF SCALED SARDINE 



FIGURE 1 . — Top. Stations in the survey area where eggs of scaled 

 sardines were collected at least once during 1971-74. Stations 

 where eggs did not occur are indicated by dots. Bottom. Stations 

 in the survey area where larvae of scaled sardines were collected 

 at least once during 1971-74. Stations where larvae did not 

 occur are indicated by dots. 



is <20 m and that nearly all are found within 

 the 30-m depth contour. Spawning adults are con- 

 fined to a band within 85 km of the coast. Klima 

 (1971) reported that scaled sardines in the Gulf 

 of Mexico usually are found within the 20-fathom 

 curve (36.5 m), but he noted occasional occurrence 

 over depths as great as 165 fathoms (302 m). 

 Brazilian scaled sardines also spawned near the 

 coast, within 18.5 km of shore where water depth 

 was <65 m (Matsuura 1972). 



There were no areas in the eastern Gulf where 

 consistently high egg or larval catches occurred 

 that would suggest great concentrations of adults. 



Consistent catches of eggs and larvae between 

 lat. 24 45'N to 25°45'N and long. 81°30'W to 

 82°30'W, as well as just north of Tampa Bay be- 

 tween lat. 28°00'N to 28°30'N and long. 82°45'W 

 to 83°15'W did indicate that scaled sardines 

 usually were abundant in those areas. 



Mean egg abundances for the 17 cruises ranged 

 from 0.00 to 67.49 under 10 m 2 of sea surface 

 (Table 1). Considering only positive stations, 

 means ranged from 19.95 to 747.09 under 10 m 2 

 (Table 1). Abundances of eggs at stations rarely 

 exceeded 100 under 10 m 2 of sea surface during 

 1971 and 1972, but frequently were between 100 

 and 1,000 under 10 m 2 during 1973 and 1974 (Fig- 

 ures 2-5). Only once, in August 1973, did abun- 

 dance of eggs exceed 1,000 under 10 m 2 ( Figure 4). 



Cruise means for scaled sardine larval abun- 

 dances ranged from 0.00 to 14.45 under 10 m 2 

 when all stations were considered, and from 0.26 

 to 51.52 under 10 m 2 at positive stations (Table 1 ). 

 At positive stations larval abundances usually 

 ranged from 11 to 100 under 10 m 2 , and exceeded 

 100 under 10 m 2 at only eight stations during 

 1971-74 (Figures 2-5). 



Most scaled sardine eggs and larvae were found 

 nearer to shore than those of either thread herring 

 or round herring (Houde 1977a, b). However, 

 there was considerable overlap in areas and sea- 

 sons of occurrence of thread herring and scaled 

 sardine spawning. Eggs and larvae of scaled sar- 

 dines and round herring did not occur together 

 because round herring did not spawn in water 

 shallower than 30 m, and most spawning by that 

 species occurred during winter. 



Temperature and Salinity Relations 



Scaled sardine eggs were collected at surface 

 temperatures from 20.8° to 30.7°C and at surface 

 salinities from 29.92 to 36.88%<>. Larvae ^5 mm 

 standard length (SL), 5 days or less in age, were 

 taken at surface temperatures from 18.4° to 30.5°C 

 and surface salinities of 27.27 to 36.88%<>. Vertical 

 sections showing temperature and salinity pro- 

 files for cruises during the scaled sardine spawn- 

 ing season indicated that surface temperatures 

 differed from those at 10 m by a maximum of only 

 1°C, but that a maximum difference of 4°C could 

 occur at 30 m. The difference between the surface 

 and the 30-m depth usually did not exceed 2°C. 

 Salinity differences between the surface and 10 m 

 were always <0.5%o and never exceeded 1.5%o 



615 



