from about 3 to 52 mm. There is a gap between about 

 52 and 194 mm and another, at the postlarval and 

 juvenile stages, between 206 and 846 mm. The latter, 

 described by de Sylva (1958) is the smallest young 

 stage known. Ueyanagi (1963) discussed methods of 

 identification for larval blue marlin based on Indo- 

 Pacific material. 



3.23 Adolescent phase 



As already discussed above, under 3.12, males 

 weighing less than 35 kg (76 lb) and females weighing 

 less than 47 kg (103 lb) have not reached sexual 

 maturity. Individuals in this category, therefore, may 

 be considered to be in the young stage or adolescent 

 phase provided they are past the juvenile stage. Two 

 specimens of young blue marlin, 846 and 1,320 mm in 

 length (tip of lower jaw to fork) were described by de 

 Sylva (1958) from the Bahamas and southeast 

 Florida, respectively. The smaller specimen weighed 

 2.3 kg (5 lb) and the other 13.9 kg (30.5 lb). 



3.3 Adult Phase (Mature Fish) 



3.31 Longevity 



Estimates of blue marlin age may be obtained from 

 analyses of modal progressions in length and weight 

 frequency. Also, the sex must be known since males 

 are much smaller than females. No definite informa- 

 tion on age is, as yet, available for the blue marlin. 



3.32 Hardiness 



As already discussed under 2.22, blue marlin have 

 been taken at surface temperatures as high as 30.5° C 

 (July) and as low as 21.7°C (February). 



Individuals captured, tagged, and liberated appear 

 to suffer no ill effects since a few have been recaptured 

 after several months of freedom. 



3.33 Competitors 



There is no definite information on this subject but 

 there are indications that in the Atlantic, the white 

 marlin, Tetrapturus albidus, might compete with the 

 blue marlin for food. In the Indo-Pacific, the striped 

 marlin, T. audax, and the black marlin, Makaira in- 

 dica, might compete with the blue marlin for food. To 

 a lesser extent the sailfish, Istiophorus platypterus, 

 and the spearfishes, T. belone, T. pfluegeri, T. 

 angustirostris, and T. georgii, might also compete with 

 the blue marlin for food. 



3.34 Predators 



My own observations agree with the well-known 

 fact that sharks frequently attack hooked blue marlin 

 especially if the fish is tired after a long fight. It is not 

 known whether sharks will attack a free -swimming, 

 healthy, blue marlin, but I have seen a mako shark at- 



tack, kill, and eat a free-swimming broadbill sword- 

 fish. 



3.35 Parasites, diseases, injuries, and 

 abnormalities 



Parasites and diseases: On several occasions, I have 

 observed ectoparasitic calgoid copepods on the head 

 of fresh-caught blue marlin. Cressey and Lachner 

 (1970) reported that the marlinsucker, Remora os- 

 teochis, occurs on the body and in the gill cavity of the 

 blue marlin where they feed on ectoparasitic 

 copepods. Their examination of marlinsucker 

 stomachs revealed the presence of Caligus and 

 Pennella on blue marlin. Ectoparasitic copepods do 

 not seem to affect the physiology, behavior, or food 

 value of the blue marlin. The copepods are apparently 

 kept in check by the marlinsucker who maintains a 

 symbiotic relationship with the blue marlin and acts 

 as a "cleaner." 



The trematode Capsala poeyi from the skin of the 

 blue marlin has been reported from Cuba by Vigueras 

 (1935), from the Gulf of Mexico by Manter (1954) and 

 Koratha (1955), and from the Pacific by Iversen and 

 Hoven (1958). 



Stomach ulcers were found in 10 of 114 blue marlin 

 examined by Iversen and Kelley (1974) in Hawaii. 

 These ulcers were noncancerous and morphologically 

 similar to gastric ulcers found in many mammals, in- 

 cluding marine mammals. Iversen and Kelley believe 

 that endoparasites or mechanical injury to the 

 stomach lining, from sharply pointed food items, are 

 the most likely cause. 



Injuries and abnormalities: Some of the blue marlin 

 specimens examined by me have had some scars or 

 malformed fins or bills. On several occasions the tip of 

 the bill has been broken off. From time to time sport 

 fishermen have told me of seeing blue marlin without 

 a bill, but I have not personally seen specimens with 

 this abnormality. Moore (1950) reported a 248-kg 

 (545-lb) blue marlin from Hawaii without a spear. 

 The appearance of the specimen indicated that the 

 spear had been lost by injury and there was no indica- 

 tion that the loss was at all recent. Moore also men- 

 tioned that the specimen was equal in condition to 

 normal blue marlin and that apparently the spear is 

 not necessary for natural and adequate feeding. He 

 also remarked that according to the operators of the 

 Honolulu market spearfishes without a spear had 

 been observed before but that such occurrences were 

 very rare. 



Erdman (1957) recorded a blue marlin with the bill 

 missing and healed at the point of rupture. The upper 

 jaw was shorter than the lower but the fish had actual- 

 ly more food in its stomach than four other blue 

 marlin captured the same day. 



Broken bills in marlin are apparently caused by the 

 pugnacity of these fishes, according to Smith (1956). 

 He states that many floating bales of rubber with 



