this and the broader area of the equatorial western In- 

 dian Ocean was confirmed by Merrett (1971). 



2.3 Determinants of Distribution Changes 



Voss (1953) stated that sailfish distributions along 

 the east coast of Florida appear to be affected by wind 

 and temperature. In the summer there is a "diffusion" 

 of sailfish to the northward correlated with a 

 northward extension of warm water. These same fish 

 are driven southward to congregate in schools off the 

 Florida coast with the beginning of cold weather and 

 northerly winds. 



Evidence presented by Ovchinnikov (1966) in- 

 dicates that the frontal zone of the Canaries Current 

 and the Equatorial Countercurrent is responsible for 

 the aggregation of sailfish off the coast of West Africa. 

 He stated that in spring sailfish move along the coast 

 from south to north, and apparently move back again 

 from north to south in the autumn, following the 28° C 

 isotherm. Similarly, Cadenat (1961) indicated that 

 the period of increased abundance off the Ivory Coast 

 coincides with the periods of maximum surface 

 temperature, around 28°C. 



In the western Pacific the distribution of postlarvae 

 and adult sailfish appears to be closely related to the 

 Kuroshio Current (Nakamura, 1949; Ueyanagi, 1959). 

 Nakamura also stated that the season of dense dis- 

 tribution in this area coincides with the spawning 

 season. Koto et al. (1959) found that sailfish over 160 

 cm long migrate southward out of the East China Sea, 

 presumably for spawning. 



In the eastern Pacific, Kume and Joseph (1969a) 

 found that seasonal north-south movements of sailfish 

 off the coast of Mexico appear to coincide with the 

 seasonal movements of the 28° C isotherm. 



Williams (1964, 1970) concluded that the abun- 

 dance and distribution of sailfish in the Indian Ocean 

 off East Africa is positively correlated with the 

 months of the northeast monsoons when the East 

 African Coastal Current reaches its maximum 

 temperature (29°-30°C) and minimum salinity (35.2- 

 35.3%o). This is also the time of highest biological 

 productivity in surface waters caused by a mixing due 

 to the junction of the southward flowing Somali 

 Current and the northward flowing East African 

 Coastal Current. The inshore penetration of nutrient 

 rich Somali Current water fluctuates seasonally. 

 Williams (1970) summarized by stating that: "The 

 known fluctuations in overall productivity and the 

 seasonal abundance of shoals of pelagic fish in the 

 north Kenyan area during the northeast monsoon 

 might well be due to the fluctuations in the penetra- 

 tion of the SC tongue." 



2.4 Hybridization 

 Nothing found in the literature. 



3 BIONOMICS AND LIFE HISTORY 

 3.1 Reproduction 



3.11 Sexuality 



Sailfish are heterosexual. There are no external 

 characters known to distinguish males from females, 

 although Jolley (1974) and Nakamura and Rivas 

 (1972) indicated that large Atlantic sailfish were 

 usually females. 



3.12 Maturity 



There is little information available on size at first 

 maturity. Merrett (1971) examined gonads from 65 

 female sailfish from the equatorial western Indian 

 Ocean but found only one immature specimen 130 cm 

 long (measured from center of orbit to shortest caudal 

 ray) and weighing 13.6 kg. According to de Sylva 

 (1957) sailfish this size in the western Atlantic are ap- 

 proximately 18 mo old. 



3.13 Mating 



Mating in large pelagic fishes has often been as- 

 sumed to be promiscuous with sexual products re- 

 leased indiscriminately and fertilization occurring by 

 chance. Nakamura (1949) stated, however, that 

 "Spawning (in sailfish) is carried on with a male and a 

 female paired or two or three males chasing a single 

 female, and this act can be seen often during the 

 spawning season." Voss (1953) reported observing 

 similar behavior in sailfish off the Florida coast. 

 Sailfish were often sighted in groups of two or three 

 swimming very slowly in shallow water. The ovaries of 

 females captured in this area were all extremely large 

 and very ripe. Voss also reported that another 

 observer sighted two sailfish pressed tightly together 

 and swimming slowly in shallow water. One was har- 

 pooned and was identified as a female containing ripe 

 overies weighing about 3.2 kg. 



3.14 Fertilization 

 Fertilization is probably external. 



3.15 Gonads 



According to Voss (1953) the number of eggs spawned 

 by a female sailfish is large based on western Atlantic 

 specimens. He determined that a 1.4-kg ovary con- 

 tained 2.3 million eggs and obtained counts as high as 

 4.7 million eggs in later analyses. Voss also stated that 

 gonads from female sailfish may be as long as 50.8 cm 

 and weigh up to 3.6 kg. Jolley (1974) showed that ripe 

 gonads of Atlantic sailfish weighed 8.1-12.5% (mean 

 9.9%) of total body weight. Fecundity estimates 

 ranged from 0.75 to 1.56 million ova. Only the most 

 advanced ova, 1.2- to 1.4-mm diameter, were counted. 

 Ovchinnikov (1970) gave fecundity estimates of 1.6- 

 11.5 million eggs from ovaries of 1.1-2.1 kg from Atlan- 



101 



