Larval development , distribution , and abundance of common dolphin , Coryphaena hippurus , and pompano dolphin , C . equiselis ( family : CoryphaenidaeJ , in the northern Gulf of Mexico

1 Hagood, R. W., and G. N. Rothwell. 1979. Sea Grant interim project report--1979. Aquaculture in tropical ocean-Coryphaena sp. Oceanic Inst., Makapuu Point, Waimanalo, HI 96795. Mexico (Gulf), but associated environmental data are not included (Richards et aI., 1984; Kelley et aI., 1986). Embryonic development is described for common dolphin (Mito, 1960; Hassler and Rainville, 1975; Hagood and RothwelP) and osteological development for both species (Potthoff, 1980), but descriptive larval morphology is primarily limited to sizes >13 mm SL (Gibbs and Collette, 1959; Shcherbachev, 1973). Okiyama (1988) and Aoki and Ueyanagi (1989) provide information on developmental morphology of Pacific specimens <13 mm SL, but their illustrations are The dolphinfishes, Coryphaena hippurus (common dolphin) and C. equiselis (pompano dolphin), are distributed worldwide in tropical and subtropical seas (Briggs, 1960). Highly prized as food, these fishes are important recreational and commercial species, but relatively little is known about their early life stages. Gibbs and Collette (1959) reviewed spawning and adult seasonal distribution for the western North Atlantic Ocean, and Palko et al. (1982) compiled dolphinfish biological data. Aoki and Ueyanagi (1989) discllssed larval and early juvenile distribution for the eastern Pacific, and similar information is available for the western Pacific and Indian oceans (Shcherbachev, 1973). Preliminary distribution maps are available for the Gulf of Abstract.Dolphinfishes are highly prized commercial and recreational species of worldwide distribution in tropical and subtropical seas, but the development and distribution of their larvae are poorly understood. Common dolphin eggs hatch in about 38 hours at 25·C based on a predictive relationship among egg diameter, water temperature, and development time. Morphometrics are generally greater in pompano dolphin than in common dolphin. Pompano dolphin are deeper-bodied and have a larger eye by 9 mm, and a larger mouth and longer pre-anal length by about 13 mm. Differences in pigment along the caudal peduncle and its finfold separate common dolphin from pompano dolphin <4.0-4.5 mm SL; common dolphin lack pigment in these areas. Number of spines along the outer shelf of the preopercle also separate species although preopercle spines are often difficult to count on larvae not cleared and stained; common dolphin have four spines along the outer preopercular shelf and pompano dolphin have five. Pigmented· pelvic fins and bands of pigment laterally on both the body and median fins of common dolphin are diagnostic for separating species >8 mm SL; pompano dolphin lack these characters. Both common dolphin and pompano dolphin larvae usually are found at ~24·C, ~33 ppt, and beyond the 50 m isobath. Preflexion larvae «7.07.5 mm SL) were primarily collected in oceanic waters. Both species may spawn year-round, at least in the southern part of the survey area. Larval common dolphin are significantly more abundant than pompano dolphin.