Age, growth, and reproduction of the dolphin, Coryphaena hippurus, in the straits of Florida

The dolphin grows rapidly throughout its life. Check marks believed to be annuli were formed from November through February. Average growth was 725 mm fork length the first year and 450 mm the second year. One older fish belonged to age-group III (1425 mm long), and another to age-group IV (1525 mm). A male dolphin in the reef tank of the Miami Seaquarium, Miami, Florida, grew from about 0.5 kg (one lb.) to 16.3 kg (36 lb.) in about eight months. Maximum life span is probably about four years. Male dolphin longer than about 450 mm were heavier than females of the same length. Reproduction was studied by gross observation of the gonads, measurements of egg diameters, and counts of maturing eggs. Changes in the gonads through the year indicated that the spawning season in the Florida Current extends from November through July and is at its peak in March. Female dolphin begin to mature at 350 mm fork length, and all are mature by 550 mm. Males begin to mature at a slightly larger size. Female dolphin produce 80,000-1,000,000 eggs at each spawning and spawn twice (perhaps as many as three times) per year.