broken bills and pelvic fins are seen to heal over rather 

 than regenerate. Striped marlin have recovered after 

 losing almost all of the bill (Wisner, 1958). 



3.4 Nutrition and Growth 



3.41 Feeding 



Most active feeding probably takes place in the 

 morning. LaMonte (1955) reported that squid found 

 in the stomachs of striped marlin off Peru and Chile 

 were less digested in fish caught in the morning than 

 those landed after noon. Kobayashi and Yamaguchi 

 (1971), examining only fish caught after noon, found a 

 decline in feeding activity toward sunset. Williams 

 (1967), however, suggests that East African fish feed 

 at any time of the day or night. 



Apparently the food is usually captured by grasping 

 with the mandibles rather than by spearing, slashing, 

 or clubbing with the bill. Fish which have lost the bill 

 completely survived well. Some food specimens are 

 occasionally found, however, which have been neatly 

 speared (Wisner, 1958; Evans and Wares, 1972). 



3.42 Food 



Several authors have reported on food habits. Table 

 4 gives an idea of the variety of food species which 

 have been found most important in different studies. 

 It is notable that, despite the large size and lack of gill 

 rakers in striped marlin, relatively small forage items 

 are commonly taken (Nakamura, 1949). 



Food habits do not appear to vary appreciably with 

 sex or size over the range of sizes commonly caught. 

 Considerable variation in species composition of the 

 diet occurs, however, with season and geographic 

 location (Evans and Wares, 1972). Such variations 

 probably reflect variations in availability of the food 

 organisms in keeping with the generally accepted con- 

 cept that these fish are broadly carnivorous, nonselec- 

 tive feeders. This is true of epipelagic fishes generally 

 (Parin, 1968). 



The average volume of food found in stomachs of 

 striped marlin caught by the eastern Pacific sport 

 fishery ranged from 14 to 23 fluid ounces per stomach 

 (Evans and Wares, 1972). Yamaguchi (1969) reports 

 that empty stomachs were found in 66% of striped 

 marlin caught by longline. This percentage tends to 

 be larger in billfish than in tunas. Evans and Wares 

 (1972) found 19% empty stomachs. 



3.43 Growth rate 



Weight-frequency modal progressions in Hawaii 

 landing data suggest an annual growth rate of about 

 30 pounds (Royce, 1957). Merrett (1971) found agree- 

 ment with Royce's data in size-frequency dis- 

 tributions from East Africa. Possible modal lengths of 

 about 152, 167, 177, and 197 cm eye-fork length were 

 found in the length-frequency distribution for the 

 total catch. Computed weights at modal lengths gave 



Table 4. — Some reported major food species for striped marlin. 



annual weight increments of 27, 21, and 23 pounds. 

 Koto (1963a) working with length-frequency data 

 from the western North Pacific, found six modal 

 groups (n though n+5). The monthly progression of 

 these modes is shown in Figure 5. The designations of 

 these modal groups are as follows: 



Group 

 n 



n + \ 

 n + 2 

 n+3 

 n+4 

 n+5 



There is a marked seasonal change in growth rate 

 with rapid growth occurring from June to November 

 and very little growth in the remainer of the year for 

 age groups ra+1, n+2, and n+3. Age group n appears 



145 



