Reproduction of tarpon, Megalopsatlanticus, from Florida and Costa Rican waters and notes on their age and growth

We examined 1,469 tarpon ranging 102-2,045 mm fork length (FL) that were collected in South Florida waters and 217 tarpon ranging 880-1,860 mm FL that were collected in Costa Rican waters from 1989 to 1994. Among the Florida tarpon, gonads of 737 fish were examined histologically, and gonadosomatic indices were calculated for 409 tarpon. Among Costa Rican tarpon, gonads of 202 tarpon were examined histologically, and gonadosomatic indices were calculated for 178 tarpon. Florida fish were significantly larger than those from Costa Rica, and sexually mature females were significantly larger than sexually mature males in both areas. All Florida males were sexually mature by 1,175 mm FL, and only one smaller male (901 mm) was mature. The smallest sexually mature Florida female was 1,285 mm FL, and all larger females except one were sexually mature. Only one Florida tarpon, a 7-yr-old female, younger than 10 yrs was sexually mature; all tarpon older than 10 yrs were sexually mature. In Costa Rica, only one immature female (880 mm FL) was examined; all other females (1,126-1,860 mm FL) were sexually mature. All Costa Rican males examined (880-1,550 mm FL) were sexually mature. Florida tarpon spawned during April-July and by August, most females were spent or recovering. Spawning in Costa Rican waters was not seasonal, and reproductively active females were caught during all months. Fecundity estimates for Florida tarpon ranged 4.5-20.7 million oocytes and had a significant positive relationship with fish weight. Otoliths of tarpon from Costa Rican waters were difficult to read. We examined thin-sectioned otoliths (sagittae) from 194 Costa Rican tarpon but could estimate ages for only 87 fish (45%). Costa Rican tarpon are long-lived and reach a maximum age of at least 48 yrs. Most (74%) tarpon caught in Costa Rica that we aged were 15 to 30 yrs old.