204 



Fishery Bulletin 88(1), 1990 



Figure 2 



A section of a hyperostosis bone in ('hn/ftiiphri/s niiratiis shows a vacuolated structure (arrows) encased with bone. 



furthest from the tail shows less enlargement, as in 

 Figure 1. Section of the snapper hyperostosic bone 

 shows the vacuolated appearance (Fig. 2) characteristic 

 of most fish bones. 



The relative size of the most caudal hyperostosis was 

 measured as the ratio of the width of the hyperostosis 

 to the width of the spinal vertebra to which the haemal 

 spine, on which the hyperostosis occurs, was attached. 

 A plot of the ratio of hyperostosis width/vertebra width 

 to fork length is shown in Figure 3. The correlation 

 between relative size of the hyperostosis and fork 

 length was low, ?■ = 0.58. The correlation between the 

 ratio of hyperostosis width/vertebra width to annual 

 check-ring age was low, r = 0.53. 



Eight pairs of hyperostoses/vertebrae were examined 

 for fat content and fat composition (Table 1 ). The mean 

 fat content of the hyperostoses (% dry matter) was 

 12.57 + 19.34, and the mean fat content of vertebrae 

 (% dry matter) was 12.53 + 13.04. Although there was 



a certain amount of variation in fat content between 

 hyperostoses and vertebrae, it was unlikely to be sig- 

 nificant in any biological sense because fish lipid com- 

 position and content have been shown to be affected 

 by diet to a greater extent than is shown in our data 

 (Worthington and Lovell 1973). 



The fatty-acid composition was almost identical 

 (±5%) for all samples and very similar to the table 

 presented in Love (1980: 414) for marine fish fatty-acid 

 composition. A typical fatty composition for five pairs 

 of hyperostoses and vertebrae is shown in Table 2. 

 There was no significant difference in fatty-acid com- 

 position between the hyperostoses and vertebrae. 



Discussion 



Hypoerostosic bones of the snapper Ckrysophrys 

 aurata increased in size with increase in size of the fish, 



