data relating to sexual maturation and to make infer- 

 ences on the reproductive biology of striped marlin 

 and sailfish. The numbers of blue and black marlin 

 were insufficient to add significantly to the knowl- 

 edge of these species. We also present notes on food 

 habits as observed from data collected in 1970, sea- 

 sonal abundance, and parasites. 



Because of the long established fishery for bill- 

 fishes in the western and central Pacific, most bill- 

 fish reproduction information has been derived from 

 that area (Nakamura, 1932, 1940, 1949; Ueyanagi, 

 1959; Yabe, 1953; Honma and Kamimura, 1958). 

 Merrett (1970, 1971) and Williams (1963, 1964, and 

 1970) reported on the Indian Ocean billfishes and 

 concluded they are closely related to those in the 

 western Pacific. We have encountered only two 

 major publications (Kume and Joseph, 1969b; Yurov 

 and Gonzales, 1972) dealing with reproduction of 

 billfishes east of long. 130°W. 



SEASONALITY 



All four of the species studied occur regularly at 

 Mazatlan and Buena Vista where they exhibit sea- 

 sonal cycles of abundance. San Diego is near the 

 northern extreme of istiophorid ranges on the east- 

 ern Pacific coast and except possibly in the warmest 

 years, striped marlin is the only species captured 

 there. The occurrence of striped marlin is highly 

 seasonal. 



Based on records kept by several resorts (1963-69) 

 in the Palmas Bay area of Baja California (the area 

 surrounding Buena Vista) and at Mazatlan 

 (1967-69), sailfish and striped marlin show distinct 

 patterns of seasonal abundance. Though these data 

 are probably not highly accurate, the trends (Fig. 

 2 and 3) agree with our personal observations and 

 with data provided by the Departamento de 

 Tourismo, Terr. Baja California Sur. Seasonalities 

 for blue and black marlin are not presented because 

 of the low numbers in the catch records and because 

 of persistent confusion in the identification of the 

 two species. It appeared, however, that blue marlin 

 were most abundant from late summer through 

 winter, at least in the Palmas Bay area. 



Peak abundance of both striped marlin and sailfish 

 tended to occur later in the year at Palmas Bay than 

 Mazatlan. At each location, the time of maximum 

 abundance of sailfish occurred later than that of 

 striped marlin. The seasonal occurrence of striped 

 marlin is much more restricted at San Diego than in 

 Mexico with no fish being caught before July 1 or 



- PALMAS &AT 



- MAZATIAN 



JFMAMJJASOND 



Figure 2. — Catch per unit effort (number per boat-day) 

 and percent effort for sailfish sport fishery from Palmas 

 Bay (1963-1969) and Mazatlan (1967-1969). 



STRIPED MARLIN 



MAIATll 



Figure 3. — Catch per unit effort (number per boat-day) 

 and percent effort for striped marlin sport fishery from 

 Palmas Bay (1963-1969) and Mazatlan (1967-1969). 



after December 1 . Records of striped marlin landed 

 at three sportfishing clubs in San Diego from 1963 to 

 1970 show the peak catch to vary between late Au- 

 gust and early October. The timing of the apparent 

 abundance of striped marlin off San Diego is be- 

 lieved to be correlated with surface water tempera- 

 tures (Squire, 1974a). 



REPRODUCTION 



Collection and Processing 

 of Samples 



Gonad weights and fish length and weight were 

 measured and sex noted of each fish examined. Dur- 

 ing 1969 and 1970 core samples of ovaries were also 



90 



