second time using weight data alone. In only one in- 

 stance was a spot placed differently. The results are 

 seen in Figure 3 and indicate the presence of at most 

 four year classes (0, I, II, HI). One-year-old fish 

 (beginning of year class I) can be expected to be about 

 800 to 1,000 mm in body length and 4 to 6 pounds. 

 Two-year-old fish are about 1,600 to 1,770 mm in body 

 length and 38 to 41 pounds. Three-year-old fish are 

 not much longer, about 1,800 mm body length, but are 

 heavier, 60 to 80 pounds. First spawning would occur 

 at the end of the second year and few fish apparently 

 survive beyond a second spawning a year later, 

 assuming that the species spawns but once per year. A 

 short life history is not surprising and this fit of the 



Figure 3. — Age and growth analysis of Tetrapturus pfluegeri 

 basd on data from the sport fishing catch in the western At- 

 lantic. (Year classes 0, I, II, and III and months of the year are 

 indicated on the ordinate. The assumed spawning time is indi- 

 cated by the horizontal line at mid-February. See text for ex- 

 planation.) 



data seems most parsimonious. That is, attempts to 

 fit the data to five instead of four year classes on the 

 basis of length or weight result in greater inconsisten- 

 cies in the other parameter than those exhibited in 

 Figure 3. The variation seen is remarkably small con- 

 sidering that a point-in-time spawning was assumed 

 when in fact spawning no doubt occurs over several 

 months. 



The writer also has available length data from the 

 Pflueger taxidermy shop records; this information was 

 provided by Donald P. de Sylva. Lengths are in 2-inch 

 increments and are measured from the rear margin of 

 the eye to the fork of the tail. These data gathered 

 from 1958 to 1967 include some of the same fish 

 analyzed by the writer, especially prior to 1964. The 

 results are similar to those above and show 4-yr 

 groupings. Because of the overlap in specimens and 

 different means of measurement these data are not 

 further treated. 



3.13 Mating 



Whether spawning is in pairs or larger groups is un- 

 known. 



3.14 Fertilization 



Nothing is known of the reproductive behavior nor 

 of fecundity. Fertilization surely is external and 

 females probably spawn but once during the year. The 

 eggs have not been described. 



3.15 Gonads 



The ovaries are unequally developed, that of the left 

 side being approximately twice that of the right. The 

 right meets the left at an angle about half way back, 

 the result is that the ovary appears Y-shaped when 

 first seen, the stem of the Y pointing forward. In 

 specimen 45 (see material examined above) the left 

 ovary was 475 mm, the right 230 mm; in specimen 41 

 these measurements are 458 and 242 mm. On the 

 other hand the left ovary in specimen 35 was 193 mm, 

 the right 212 as determined by W. P. Davis. The testes 

 are similarly asymmetrical, again the left side being 

 longer. In specimen 27 the two measured 65 and 30 

 mm and in specimen 14 (see Fig. 4) the two are 205 

 and 110 mm. A study of changes in gonad size and 

 shape with maturation is needed. In those specimens 

 with asymmetrical gonads the junction point of the 

 "Y" is almost directly above the anus. Merrett 

 (1970:357, pi. 16) notes that of all istiophorids ex- 

 amined by him in the Indian Ocean, only T. 

 angustirostris Tanaka has asymmetrical gonads and 

 that the left is the longer, the junction being at the 

 level of the urogenital operture. 



3.2 Preadult Phase 



De Sylva and Ueyanagi, on the occasion of the 

 International Billfish Symposium at Kona, August 

 1972, showed slides of larvae which they identified as 



34 



