1950 and November 1957-January 1958 were not in a 

 breeding condition. He concluded that most 

 istiophorids apparently spawn in the summer months, 

 roughly May through September. 



Williams (1963) stated that sailfish move into 

 coastal waters of Kenya in December, January, and 

 February for spawning based on the presence of ma- 

 ture and spent adults in the area. Merrett (1971), 

 however, suggested that the abundance of sailfish in 

 inshore waters off Kenya was not for spawning but 

 was a postspawning, feeding migration and reported 

 capturing two running-ripe sailfish on longline gear 

 approximately 111 km from the coast, one in January 

 and the other in April. Williams (1970) revised his 

 earlier spawning hypothesis and concluded that a 

 combination of the two hypotheses was most likely 

 correct. Jones (1959) indicated an additional spawn- 

 ing locality in the Laccadive Sea. 



3.17 Spawn 



A redescription of the egg of /. platypterus is given 

 by Nakamura (1949) who wrote: "The ripe ovarian 

 eggs are about 0.85 mm. in diameter and they have a 

 single oil globule. Around the oil globule there is a 

 pale yellow indefinite nimbus. There are no structures 

 on the vitelline membrane and the egg as a whole is 

 almost colorless and clear." Merrett (1970) described 

 oogenesis and spermatogenesis in this and other 

 billfish species. He measured eggs shed from a cap- 

 tured sailfish and reported that the mean diameter 

 was 1.304 mm. He also examined the morphology of 

 the spermatozoa of this species and Tetrapterus 

 audax and Makaira indica. Measurements showed the 

 heads to be 1.3-1.9 /ura in diameter; in length, the mid- 

 dle pieces measured 0.8-1.3 urn, and the tails up to 

 30 um.The only difference observed between the 

 species was that the heads of the spermatozoa in 

 sailfish tended to be in the upper part of the diameter 

 range, and the middle pieces were found generally to 

 be shorter than in the other two species. 



3.2 Preadult phase 



3.21 Embryonic phase 



(Defined as from fertilization to hatching, i.e., dur- 

 ing incubation period.) Nothing found in the 

 literature. 



3.22 Larvae phase 

 See 3.23. 



3.23 Adolescent phase 



Since young of these fishes gradually transform 

 from larvae to adults, both the larval phase and 

 adolescent phase are discussed here in one unit. 



Young billfishes (Istiophoridae) are all very similar 

 in their development, and consequently identification 



of the young stages is difficult. The first description of 

 a young sailfish was by Cuvier (in Cuvier and Valen- 

 ciennes, 1831). This specimen was 108 mm long and is 

 the type specimen of Histiophorus pulchellus (see 

 1.12). Riippell (1835) reported on a 45.7-cm juvenile 

 from the Red Sea which he described as H. im- 

 maculatus. Giinther (1873-74) published figures of 

 young billfish 9, 14, and 60 mm long, and these were 

 republished in one of his later works (1880). Liitken 

 (1880) also republished these figures as well as a 5.5- 

 mm specimen of his own. It is difficult to say positive- 

 ly that the specimens of Giinther and Liitken are in 

 fact sailfish. Goode (1883) also republished these 

 figures and included an English translation of Liitken 

 (1880). LaMonte and Marcy (1941) described a 14- 

 mm specimen, and Beebe (1941) described two 12-cm 

 specimens. Beebe also reviewed briefly the early work 

 mentioned above and republished all of the figures 

 mentioned. However, the fine detail presented in the 

 earlier figures was not reproduced by Beebe and for 

 detailed study we recommend that the original work 

 be consulted. Descriptions of occasional specimens 

 thought to be sailfish have appeared prior to papers 

 describing complete series. Such descriptions are by 

 Nakamura (1932, 1940, 1942, 1949) and Deraniyagala 

 (1952). 



Two studies describing complete series of larval 

 through juvenile stages of sailfish were published in 

 1953, one by Voss based on Atlantic specimens and 

 the other by Yabe based on Pacific specimens. Follow- 

 ing these two papers, several papers also described 

 sailfish based on complete series or else give impor- 

 tant data on young forms. These studies are by 

 Gehringer (1956, 1970), Jones (1959), Sun (1960), 

 Ueyanagi and Watanabe (1962, 1964), de Sylva 

 (1963), Ueyanagi (1963b) Mito (1966, 1967), and 

 Strasburg (1970). We have reproduced here the 

 figures of larval sailfish from Gehringer 1956 and 1970 

 (Fig. 4) that best delineate changes which take place 

 during development. The most striking features are 

 the early development of prominent pterotic and 

 preopercular spines, the beaklike snout, and the very 

 dark pigmentation which is acquired in early stages. 

 At lengths greater than 10 mm the large dorsal fin 

 begins to develop and with the long bill make this a 

 most striking juvenile. 



When seen in life between 4 and 15 mm in length 

 the dark area is dark metallic blue (brown when 

 preserved); the belly silvery (white when preserved); 

 the head area, particularly the opercles, are flecked 

 with a brilliant gold (this is lost soon after preser- 

 vation); and the dorsal fin is a deep velvety black. The 

 juvenile is colored very similar to the adult. 



Ueyanagi (1963a, 1964) gave methods for dis- 

 tinguishing sailfish young from the other billfish 

 species in the Indo-Pacific. His methods (1964 paper) 

 are as follows: 



It is not easy to identify the larvae of different istiophorid 

 species, because of their close resemblance with each other and 



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