length) are taken by longline. The shape of the first 

 dorsal fin in these fish differs from the adults in that 

 the posterior rays are still high (Ueyanagi, 1957b). 

 Fish and squid are found in the stomachs, as in the 

 adults. 



Following the 1954 hydrogen bomb test in Bikini, it 

 was reported that virtually all of the radioactively 

 contaminated striped marlin found in the 

 northwestern Pacific were fish under 130 cm long 

 (Anon., 1955). It is not clear what the implications are 

 with respect to ecological differences between young 

 and adult fish. 



3.3 Adult Phase (Mature Fish) 



3.31 Longevity 



The ability to determine age of individual striped 

 marlin has not been developed and thus life tables 

 cannot be developed and life expectancy and max- 

 imum age are unknown. 



Koto (1963a), using size-frequency data from 

 western Pacific catches, was able to discern six age 

 classes (which he designates as n though n + 5) in fish 

 greater than 100 cm eye-fork length. The Walford 

 growth transformation of his data indicated an ul- 

 timate size of about 290 cm. Specimens of this size are 

 apparently occasionally taken in the South Pacific 

 (Honma and Kamimura, 1958). From the general 

 pattern of growth indicated by Koto, fish of this size 

 would be expected to be at least 10 yr old. 



3.32 Hardiness 



Very little is known. Because of the large size and 

 activity of this species, physiological experimentation 

 is difficult. The return rate for tagged fish is much 

 higher for striped marlin than for sailfish (Squire, 

 1974), and this may indicate greater general hardiness 

 for striped marlin. Healing of severely broken bills 

 (Wisner, 1958) may also be an indication of hardiness. 

 Sportsmen usually report that the striped marlin 

 fights harder than the sailfish when hooked and tends 

 not to die as easily as the sailfish. 



3.33 Competitors 



The other billfishes, particularly the smaller species 

 (sailfish and probably the shortbill spearfish), sword- 

 fish, and the larger tunas are probably the closest 

 competitors for food. Even the smaller scombrids 

 share many forage species with the striped marlin. 

 The dolphin and pelagic sharks such as Prionace, 

 Carcharhinus, and Isurus utilize many of the same 

 forage species (Parin, 1968). Striped marlin tend to 

 feed more on epipelagic species and less on 

 mesopelagic species than the oceanic tunas or the 

 swordfish. 



3.34 Predators 



Predators of adults are probably extremely limited, 

 the only likely candidates being some of the large 

 pelagic sharks and the toothed whales. 



Bills of billfishes have been found in floating objects 

 and other fish. Occasionally bills of striped marlin are 

 found to have been broken off, and the fish are known 

 sometimes to ram fishing boats when hooked, but it is 

 not certain that any of these occurrences have any 

 relation to defense or aggressive action. 



3.35 Parasites, diseases, injuries, and ab- 

 normalities 



Parasites and diseases: The body surface usually 

 harbors many caligoid copepods which frequently 

 congregate on the ventral surface, particularly in the 

 area around the anal fin and on the head. Williams 

 (1967) reports they may occur in the thousands. The 

 skin surface in areas of concentration often appears 

 red and irritated. Penellid copepods (Penella fillosa) 

 are frequently found penetrating the skin and 

 anchored in the muscle or sometimes in internal 

 organs such as the gonads. Koga (1967) reports the 

 percentage occurrence of caligoid copepods and 

 penellid copepods on striped marlin in Fiji waters was 

 100% and 20%, respectively. Eldridge and Wares 

 (1974) report the percent occurrence of penellids 

 above and below the lateral line on one side of the 

 body as 26.2% and 22.8% with average infections of 

 3.3 and 2.3 copepods per fish. Stalked barnacles 

 (Conchoderma irgatum) frequently are attached to 

 the penellid copepods and often to the marlin skin, 

 normally near the vent (Williams, 1967). Digenetic 

 trematodes were reported found on the gills by 

 Williams (1967). Monogenetic trematodes of the fami- 

 ly Capsalidae are quite common on the surface of the 

 skin (Eldridge and Wares, 1974). 



Cestode worms resembling Dibothrium 

 manubriformes have been found in the intestines and 

 nematodes (Contracaecum incurvum) are very com- 

 mon in the stomach occurring in densities greater 

 than 200 per stomach (Morrow, 1952b). The copepod, 

 Philichthys xiphiae, has been found in the mucus 

 canals of the preopercular and opercular bones, and 

 capsalid trematodes are commonly found in the nasal 

 capsule (Eldridge and Wares, 1974). 



Injuries and abnormalities: Gastric ulcers were 

 reported in 14% of 563 eastern Pacific striped marlin 

 (Evans and Wares, 1972). These may be associated 

 with the presence of nematodes (R. T. B. Iversen, 

 Southwest Region, National Marine Fisheries Ser- 

 vice, NOAA, Honolulu, Hawaii, pers. commun.). The 

 small squaloid shark (Isistius brasiliensis), the 

 probable cause of crater wounds on many pelagic 

 fishes including istiophorids (Jones, 1971), probably 

 parasitizes striped marlin. 

 There is evidently little ability for regeneration as 



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