AGE AND GROWTH OF DOLPHIN, 



CORYPHAENA HIPPURUS, 



AS DETERMINED BY GROWTH RINGS 



IN OTOLITHS 



The dolphin, Coryphaena hippurus Linnaeus, is a 

 large, schooling, pelagic fish with a worldwide dis- 

 tribution in warm seas. Its range extends from the 

 Tasman Sea (Shcherbachev 1973) to Nova Scotia 

 (Vladykov and McKenzie 1935). It supports impor- 

 tant game and commercial fisheries in the Caribbean 

 (Mahon et aL 1982), Southeastern United States 

 (Beardsley 1967), East Africa (Williams 1956), 

 Taiwan, Japan, China, and Hawaii (Hagood et aL 

 1981). 



Growth rates of dolphin have been estimated using 

 scale annuli (Beardsley 1967; Rose and Hassler 

 1968), modal progression of length- frequency dis- 

 tributions (Wang 1979), and captive fish of known 

 age (Herald 1961; Beardsley 1971; Hassler and 

 Rainville 1975; Hagood et al. 1981). However, scale 

 annuli are not present in all dolphin populations 

 (Schuck 1951; our study population) and are of 

 limited use in aging a short-lived species. Modal pro- 



gression of length frequencies, when appropriate, 

 provides little information on intrapopulation growth 

 variability; and fish growth in captivity is not 

 necessarily representative of growth in the wild. 



Daily rings on otoliths have now been used to age 

 temperate and tropical fish (e.g., Pannella 1971, 

 1974; Brothers et al. 1976; Taubert and Coble 1977; 

 Uchiyama and Struhsaker 1981; Rosenberg 1982; 

 Campana and Neilson 1982). In this paper, we de- 

 scribe the sagittal otoliths of dolphin and suggest that 

 they can be used to estimate age and growth in 

 this species. 



Materials and Methods 



Dolphin were caught between January 1981 and 

 June 1982, 10-40 mi offshore Barbados, using troll- 

 ing lines for adults and surface gill nets for juveniles. 

 Each fish was measured for standard length (SL) to the 

 nearest mm. Monthly length- frequency distributions 

 were drawn. Changes in mean length of a cohort were 

 used to estimate the growth rate of adults. 



The sagittal otoliths of the dolphins were removed 

 from the sacculi, mounted on a glass slide in the syn- 



Fn;i'RE 1.— Right sagitta of Coryphaena 

 hippurus (307 mm SL) viewed from the 

 lateral surface. R= rostrum, A = antiros- 

 trum, E = excisural notch, P = primor- k 

 dium, v, = radial measurement. 



906 



FISHERY BULLETIN: VOL. 84, NO. 4, 1983. 



