avoid it or are exceptionally poor swimmers at this 

 stage of development. 



Also noteworthy is the apparent brevity of the 

 spawning season in the northern and southern edges 

 of distribution. Although spawning is indicated for 

 most months of the year in the vicinity of the 

 equator, it extended for only 4 mo, April to July, in 

 the areas above lat. 20°N. By contrast, blue marlin 

 and shortbill spearfish spawning extended over 5 and 

 6 mo. May through September and May through 

 October, respectively, in Hawaiian waters. 



The captures of swordfish larvae off Hawaii also 

 provided new information on the lowest tempera- 

 tures in which this species spawn. Two larvae (9.6 

 and 9.8 mm) were taken at long. 157°W in 23.3° and 

 23.6°C water, well below the lowest temperature 

 previously recorded in the Pacific and comparable to 

 the 23.5°C recorded from the southwestern Atlantic 

 by Taning (1955). 



DISCUSSION 



A comparison of the species composition of bill- 

 fishes taken on the longline and the young taken in 

 plankton nets in Hawaiian waters leads to interesting 

 speculations concerning the spawning behavior of 

 certain istiophorids. For example, the striped marlin 

 is the predominant species taken commercially, in 

 terms of both number and weight offish caught. An 

 average of 5,685 striped marlin, which make up 

 81.6% of all istiophorids caught on the longline, were 

 taken annually from 1966 to 1970. Yet, no larva of 

 this species has been recognized from our samples. 

 Alternatively, blue marlin and shortbill spearfish 

 comprise only 9.8% and 3.4%, respectively, of the 

 istiophorids taken on the longline, but they make up 

 the entire catch of young taken in these waters. 

 Larvae of sailfish and black marlin also have not 

 been recognized in our catches. These two species 

 combined represent only 4.5% of the istiophorids 

 taken on the longline. 



The absence of striped marlin larvae in Hawaiian 

 waters is probably due to absence of spawners. 

 Length-frequency data (Royce, 1957; Howard and 

 Ueyanagi, 1965) show that very young fish less than 

 150-cm modal length (11 kg 2 ) first appear in the 

 fishery in the fall and remain there continuously 

 through two successive seasons, by which time they 

 have attained a modal length of 220 cm (45 kg). No 



Conversion of weight (lb) to estimated length (cm) through 

 courtesy of R.A. Skillman. Honolulu Laboratory. 



one has yet studied the size of striped marlin at initial 

 spawning but it is suspected that fish in the last 

 modal group may have reached sexual maturity, 

 since fish of similar sizes were found with ripe 

 gonads in the western Pacific between lat. 15° and 

 30°N (Howard and Ueyanagi, 1965). A more striking 

 phenomenon about the striped marlin fishery in 

 Hawaii is that fish in the last modal group disappear 

 in July and do not reappear as a group in the fishery. 

 To be sure striped marlin larger than this modal size 

 have been taken there but only in small quantities 

 comprising less than 1% of the total monthly 

 catches. 



On the basis of the discussion above and the oc- 

 currence of both larvae and adults with ripe gonads 

 only in the area between lat. 15° and 30°N, west of 

 long. 170°E (Howard and Ueyanagi, 1965) in the 

 North Pacific, it is logical to assume that the striped 

 marlin in Hawaiian waters leave the islands to 

 spawn, most likely in the western North Pacific. If 

 this is so, the spawning habit of this species differs 

 significantly from that of blue marlin, which spawn 

 almost continuously between lat. 30°N and 25°S in 

 the western and central Pacific. 



The absence of sailfish larvae in the central 

 Pacific, except in the western South Pacific (New 

 Hebrides Islands), suggests that this species also 

 may spawn in selective areas. 



LITERATURE CITED 



ARATA, G.F.. JR. 



1954. A contribution to the life history of the swordfish. 

 Xiphias gladius Linnaeus, from the South Atlantic coast of 

 the United States and the Gulf of Mexico. Bull. Mar. Sci. 

 Gulf Caribb. 4:183-243. 

 BARTLETT. M.S. 



1949. Fitting a straight line when both variables are subject to 

 error. Biometrics 5:207-212. 

 HOWARD. J.K.. and S. UEYANAGI. 



1965. Distribution and relative abundance of billfishes (7s- 

 tiophoridae) of the Pacific Ocean. Stud. Trop. Oceanogr. 

 (Miami), 2, 134 p. 

 JONES, S., and M. KUMARAN. 



1964. Distribution of larval billfishes (Xiphiidae and Is- 



tiophoridae) in the Indo-Pacific with special reference to 



the collections made by the Danish Dana Expedition. In 



Mar. Biol. Assoc. India, Proc. Symp. Scombroid Fish., 



Part 1:483-484. 



NAKAMURA, H.. T. KAMIMURA, Y. YABUTA, A. 



SUDA, S. UEYANAGI. S. KIKAWA, M. HONMA, M. 



YUKINAWA, and S. MORIKAWA. 



1951. Notes on the life-history of the sword-fish. Xiphias 

 gladius Linnaeus. [In Engl.] Jap. J. Ichthyol. 1:264-271. 



245 



