Figure 5. — The convex distal surface 

 of the left sagitta of a 27.7 kg sailfish; N 

 indicates nuclear (corel region il8x). 

 Bar = 1 mm. 



Figure 6. — Cross section of the rostral lobe of a sailfish sagitta 

 that shows incremental growth in the internal structure 

 (1,100 X). Bar = 10 urn. 



Discussion 



The otoliths from sailfish are very small in rela- 

 tion to the size of the fish and appear to be unique, 

 as their prominent ridges on the rostral lobe are 

 different from the morphology of other teleost 

 otoliths. For comparison of morphological fea- 

 tures, excellent surveys of otoliths from a broad 

 range of families and geographic areas are found 

 in Hecht (1978) and Morrow (1979). The external 

 ridge feature makes it possible to use the sagitta of 



The left lapillus (L) and asteriscus ( A) of a 27.7 kg 

 sailfish ( 18 X ). Bar = 0.5 mm. 



the sailfish for determination of age and growth 

 rates. 



de Sylva (1957) proposed that sailfish average 

 183 cm TL and attain an average weight of 10 kg at 

 the end of the first year, but the Petersen's method 

 which he used has several limitations (Watson 

 1964). It is most suitable for fish in their early life, 

 with species that have a short annual spawning 

 period, and large samples are required as indi- 

 viduals cannot be aged. The biology of sailfish does 

 not lend itself to analysis by the Petersen tech- 

 nique. This was recognized by Jolley (1974, 1977), 

 who utilized hard parts (dorsal spines) for age 

 determinations. Our estimates of growth rates 

 and age estimates are similar to his. However, 

 Jolley (1977) found that only 24% of the samples 



364 



