FISHERY BULLETIN: VOL. 85, NO. 3 



Table 4 and Figure 5 show the vertebral, dorsal 

 fin ray, and anal fin ray counts for the length 

 classes within the samples. The counts include 

 both cartilageous and ossified fin rays. The full 

 complement of dorsal fin rays is not developed 

 until the larvae have attained a size of approxi- 

 mately 40 mm. The full complement of anal fin 

 rays were developed by a size of 35-40 mm total 

 length. Richards (1982) stated that fin ray devel- 

 opment varied greatly in 21 specimens of both 

 species but first appeared at 12-13 mm and was 

 completely developed in 23 mm larvae of A. amer- 

 icanus. Fin rays first appeared at 14-15 mm in A. 

 dubius, but the full complement was not present 

 until after the larvae were greater than 25 mm 

 total length. Scott (1972) found that the definitive 

 number of anal fin rays were attained at a later 

 stage in growth than 30 mm and that the defini- 

 tive number of dorsal fin rays was attained at 

 about 30 mm for Scotian Shelf A. dubius. 



Figure 5 indicates that the definitive number of 

 vertebrae is achieved by a total length of approx- 

 imately 20 mm. As mentioned above, at sizes 

 smaller than this, the notochord had not been 

 replaced by vertebrae. This resulted in clear re- 

 gions along the column. It was not possible to 



Table 4. — Results of vertebral, dorsal fin ray, 

 and anal fin ray counts for the length classes of 

 sand lance 



count myomeres because the staining process re- 

 sulted in the fleshy parts of the body being 

 cleared. 



Matarese et al. (1980) pointed out that consid- 

 erable variation occurs in the development of 

 meristic structures of Pacific tomcod, Microgadus 

 proximus. because the size at which bone ossifies 

 varies from specimen to specimen. Figure 5 illus- 

 trates this variation in the mean counts of dorsal 

 and anal fin rays at the smaller length classes. 



Species Identification 



Sand lance larvae collected in Fortune Bay in 

 June 1979 had a mean vertebral count of 73.98 

 (SD = 1.66) (Table 4, Fig. 5). From Figure 5 and 

 Table 4, the definitive number of dorsal fin rays 

 varies from 64 to 68 with a mean of 65.53, and 

 similarly the definitive number of anal fin rays 

 varies from 32 to 36 with a mean of 34.09 (Table 



80 



01 70 



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a: 



§ 40 



30 



20 

 36 



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 < 



a: 



32 



30 



. 28 

 o 



2 



26 

 24 

 78 



LlJ 

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S 76 h 



74 

 72 

 70 L- 



DORSAL FIN RAYS 



I 1 



ANAL FIN RAYS 



VERTEBRAE 



20 



30 



40 

 LENGTH (MILLIMETERS) 



50 



60 



Figure 5. — Development of definitive number of dorsal fin rays, 

 anal fin rays, and vertebrae with increasing size of sand lance, 

 showing mean and standard deviation for each length class. 



638 



