JOHNSON and LOESCH: MORPHOLOGY AND DEVELOPMENT OF AMERICAN SHAD 



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Notochord - Standard Length (mm) 



FIGURE 3.— Scatterplot of PDL/SL for larval A losa sapidissima. Regression equation: 

 PAL = 2.62 + 0.39SL:r 2 = 0.964. 



iccounts for the decrease in predorsal body propor- 

 tions from 66.7 to 43.6% of the SL. This decrease is 

 reported to be common for clupeoid larvae (Ahlstrom 

 1968; Houde et al. 1974; Jones et al. 1978). 

 Larvae of A. sapidissima are relatively big-headed 

 in comparison to their thin nonrobust body in the pre- 

 flexion and flexion stages. Head development is 

 prominent in larvae between 8 and 11 mm. Five 

 branchial arches, jaws, and two pairs of recurved 

 teeth in the lower jaw were also evident in larvae this 

 size. HL averages 14.7% of SL between 8 and 1 1 mm 

 (Table 1). At 12 mm, HL increases to 17.0% of SL. An 

 increase of 1 .2% is evident in the HL/SL relationship 



for larvae 12-17 mm. HL increases from 20.1 to 

 27.5% of SL in larvae 18-31 mm. 



The HL/SL relationship is not as obvious in late 

 flexion and postflexion larvae because the body has 

 become more robust. E xamination of Figure 4 at first 

 tends to indicate a linear relationship between HL 

 and SL. However, there appears to be a point in 

 Figure 4 at the transformation between the flexion 

 and postflexion stages (18 mm SL) where the HL/SL 

 relationship may exhibit allometric growth. Fitting 

 the data to the model for an allometric growth curve 

 (Sokal and Rohlf 1969) produced a higher coefficient 

 of determination (r 2 = 0.992). Thus the HL/SL ratio 



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Figure 4. — Scatterplot of HL/SL for larval Alosa sapidissima. Regression equation: 

 In (HL) = In 0.05 + 1.50 In (SL)x 2 = 0.992. 



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