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Fishery Bulletin 93(4). 1995 



tree et al., 1992; Crabtree, 1995). Smith (1980) esti- 

 mated the length of the larval phase to be 2-3 

 months, but little is known about the processes that 

 transport larvae from offshore spawning grounds to 

 inshore juvenile habitat. Metamorphic larvae are 

 typically found inshore in mangrove-lined estuaries 

 but also occur in temperate Spartina marshes (Har- 

 rington, 1958 and 1966; Erdman, 1960; Wade, 1962; 

 Mercado and Ciardelli, 1972; Tucker and Hodson, 

 1976; Chacon et al., 1992). Young-of-the-year (YOY) 

 tarpon occur in small stagnant pools and sloughs of 

 various salinities and have been reported from North 

 Carolina (Hildebrand, 1934), Georgia (Rickards, 

 1968), Florida (Wade, 1962 and 1969), Texas 

 (Simpson, 1954; Marwitz, 1986), Caribbean islands 

 (Beebe, 1927; Breder, 1933), and Central America 

 (Chacon et al., 1992). 



Age and growth of tarpon are poorly documented. 

 Previous age estimates based on the examination of 

 scales suggest a maximum life span of about 15 years 

 (Breder, 1944; de Menezes and Paiva, 1966). Studies 

 on a variety of species show that scales are not reli- 

 able for ageing long-lived fishes and that scale-de- 

 rived age estimates are typically lower than esti- 

 mates derived from sectioned otoliths (Beamish and 

 McFarlane, 1983; Casselman, 1983). Ageing of tar- 

 pon based on sectioned otoliths is needed to evalu- 

 ate the accuracy of the ages estimated by Breder 

 (1944) and de Menezes and Paiva (1966). In this ar- 

 ticle, we describe age and growth of tarpon from 

 South Florida waters on the basis of an examination 

 of sectioned otoliths. 



Methods 



We obtained tarpon from a variety of sources through- 

 out South Florida from April 1988 to November 1993. 

 Most large fish (>1,100 mm FL) were obtained from 

 taxidermists in Fort Myers and Fort Lauderdale; the 

 fish had been caught in either the Florida Keys or 

 Boca Grande Pass on Florida's Gulf coast (26°43'N, 

 82°16'W). A second source of large fish was tourna- 

 ments held in the Keys, Boca Grande Pass, and the 

 Tampa Bay area (27°40'N, 82°35'W). All large tar- 

 pon were caught with hook-and-line gear. Small tar- 

 pon (<1,100 mm FL) were taken with cast nets, hook- 

 and-line gear, electroshockers, trammel nets, and gill 

 nets at various locations in South Florida. Young-of- 

 the-year tarpon were caught most effectively with 

 cast nets of various mesh sizes and ranging in ra- 

 dius from 2.1 to 3.1 m. We sampled YOY tarpon 

 monthly from November 1988 to April 1991 at two 

 sites in South Florida. On the Atlantic coast, we 

 sampled Jack Island State Park (27°30'N, 80°18'W), 



a 159.5-ha, impounded saltmarsh immediately ad- 

 jacent to the Indian River Lagoon. The site consisted 

 of a series of ditches that surrounded brackish wet- 

 lands and that were connected by flood gates to the 

 Indian River Lagoon. The second site was located on 

 the Gulf coast approximately 1.6 km south of U.S. 

 Highway 41 and 3.2 km east of Collier-Seminole State 

 Park near Naples (25°58'N, 81°33'W). This site con- 

 sisted of a series of mangrove-lined ponds and bor- 

 row ditches resulting from road construction in the 

 salt marsh. 



Standard length (SL), fork length (FL), and total 

 length (TL) were measured to the nearest millime- 

 ter (mm). All lengths reported are fork lengths. Large 

 tarpon (>1,100 mm) were weighed to the nearest 0.5 

 kg, and smaller tarpon were weighed to the nearest 

 gram. Otoliths (sagittae) were removed, cleaned with 

 bleach (5.25% sodium hypochlorite), and rinsed first 

 in water and then in 95% ethanol. Otoliths were 

 stored dry or in 95% ethanol until sectioned. Sex was 

 recorded and confirmed histologically. 



Undamaged otoliths were weighed to the nearest 

 0.01 mg. Weights of left and right otoliths were not 

 significantly different (paired <-test, n-270, £=0.039, 

 P=0.97); therefore, otolith weights were pooled for 

 analysis. If both left and right otolith weights were 

 available for an individual fish, the mean of the two 

 weights was calculated. Linear regressions were fit 

 to log 10 -transformed otolith weight and age data and 

 were compared with a £-test (Zar, 1984). 



Generally, the left sagitta was used for age esti- 

 mation; however, if the left otolith was broken, lost, 

 or destroyed during processing, the right otolith was 

 substituted. We prepared otoliths for age estimation 

 by embedding them in Spurr (Secor et al., 1992), a 

 high-density plastic medium. A 1-2 mm thick trans- 

 verse section containing the otolith core was cut with 

 a Beuhler Isomet low-speed saw with a diamond 

 blade. The section was mounted on a microscope slide 

 with thermoplastic glue (CrystalBond 509 adhesive) 

 and polished with wet and dry sandpaper (grit sizes 

 ranging from 220 to 2,000) until the annuli were vis- 

 ible. Sections were then polished on a Beuhler pol- 

 ishing cloth with 0.05-(i gamma alumina powder to 

 remove scratches. Annuli were counted three times 

 by each of two independent readers using compound 

 microscopes. Mean counts of each reader were not 

 significantly different (paired /-test, n=l,099, £=1.30, 

 P=0.193); therefore, all six counts were used to cal- 

 culate a mean age. All counts and measurements were 

 made along the ventral sulcal ridge (Fig. 1A); the dor- 

 sal ridge was used only as an aid to interpretation. 

 Measurements were made with an ocular micrometer. 



Tarpon otoliths were often difficult to interpret; 

 therefore, we established the following criteria to 



