Growth rates of captive dolphin, 

 Coryphaena hippurus, in Hawaii 



Daniel D. Benetti 



Rosenstiel School of Marine and Atmospheric Science 

 Division of Marine Biology and Fisheries, University of Miami 

 4600 Rickenbacker Causeway. Miami, Florida 33149 



The Oceanic Institute, Makapuu Point 

 PO. Box 25280, Honolulu, Hawaii 96825 



Edwin S. Iversen 



Rosenstiel School of Marine and Atmospheric Science 

 Division of Marine Biology and Fisheries, University of Miami 

 4600 Rickenbacker Causeway, Miami, Florida 33 1 49 



Anthony C. Ostrowski 



The Oceanic Institute, Makapuu Point 

 PO. Box 25280, Honolulu, Hawaii 96825 



Dolphin, Coryphaena hippurus, 

 also known as mahimahi or dolphin 

 fish, are pelagic, predatory fish dis- 

 tributed in tropical and subtropical 

 regions throughout the world 

 (Johnson, 1978; Palko et al., 1982). 

 They are an important resource, 

 supporting commercial and sport 

 fisheries throughout their range 

 (Oxenford and Hunte, 1986) as well 

 as having considerable potential for 

 aquaculture (Hagood et al., 1981; 

 Szyper et al., 1984; Kraul, 1989, 

 1991). 



Gibbs and Collette (1959) and 

 Palko et al. (1982) reviewed the dis- 

 tribution and biology of dolphin, 

 including age and growth data on 

 wild and captive fish. Age and 

 growth of wild (Oxenford and 

 Hunte, 1983) and captive (Uchi- 

 yama et al., 1986) fish have been 

 estimated from daily increments on 

 otoliths and scale annuli (Beards- 

 ley, 1967; Rose and Hassler, 1968), 

 from modal progression in length- 

 frequency distribution (Wang, 

 1979), and from fish of known age 

 reared in captivity (Hassler and 



Hogarth, 1977; Hagood et al., 1981; 

 Szyper et al., 1984; Ostrowski et al., 

 1989, 1992; Iwai et al., 1992). There 

 is considerable variability in the 

 data, reflecting environmental and 

 nutritional differences associated 

 with experimental designs for cap- 

 tive fish, as well as differences in 

 size, age, and origin of wild fish. In 

 this paper, growth rates of dolphin 

 reared in Hawaii are presented and 

 compared with those of captive and 

 wild dolphin from different popu- 

 lations, as well as other teleost spe- 

 cies. The data presented suggest 

 that there are differences in growth 

 rates and morphology between cap- 

 tive and wild dolphin. 



Materials and methods 



Fish were reared in captivity at The 

 Oceanic Institute, Hawaii, from 

 eggs obtained from wild Hawaiian 

 broodstock fish (Fjj first genera- 

 tion) maintained at Anuenue Fish- 

 eries, State of Hawaii. Up to 3 

 months-of-age juveniles were fed a 



semi-moist (27.86% moisture) 

 manufactured diet (pellet) twice 

 daily (4% of their body weight per 

 day). The diet contained 53.75% 

 crude protein, 21% crude fat, and a 

 caloric content of 5.13 calmg -1 (dry 

 matter basis). Between 3 and 9.5 

 months, fish were fed to satiation 

 once a day on a mixed diet of ex- 

 truded salmon pellet (Moore-Clarke), 

 frozen squid, and fish. The feed con- 

 version ratio (FCR) is expressed as 

 a ratio between the dry weight of 

 the total amount of food given and 

 the weight gain of live fish. 



Up to 3 months-of-age juvenile 

 fish were reared in an outdoor cir- 

 cular tank of 18,800 L (4 m diam- 

 eter x 1.5 m water column height). 

 After 3 months, fish were trans- 

 ferred to a 28,000-L tank (6 m di- 

 ameter x 1 m water column height) 

 used for broodstock maintenance. 

 Both tanks had running ambient 

 seawater (25-27°C and 33-35 ppt 

 salinity) at high flow rates (water 

 turnover rate was at 10 tank vol- 

 umes per day) and under constant 

 aeration. 



The initial population was 48 

 fish, stocked at approximately 3 

 fish per m 3 . Growth data presented 

 correspond to pooled male and fe- 

 male fish periodically sampled dur- 

 ing the period studied (1-9.5 

 months). Data are of individually 

 sampled fish and are not averages. 

 Small fish (1—3 months) were 

 sampled daily. Sampling frequency 

 of intermediate (3-6 months) and 

 large (6-9.5 months) fish was weekly 

 and bimonthly, respectively, owing to 

 difficulties in handling larger dol- 

 phin and because there were fewer 

 individuals available for sampling. 

 Since dolphin metamorphosis oc- 

 curs during the third week after 

 hatching and one month-old fish 

 are fully developed juveniles (Be- 

 netti, 1992; Kim et al., 1993), all 

 data corresponding to fish from 1 

 to 9.5 months-old were combined. 



Manuscript accepted 31 May 1994. 

 Fishery Bulletin 93:152-157 (1995) 



152 



