Tarpon, continued 



(Henshall 1 895, Breder 1 944, Randall 1 959, Harrington 

 and Harrington 1960, Tabb et al. 1962, Wade 1962, 

 Hildebrand 1963, Rickards 1968, Wade 1969, Odum 

 1 971 , Hoese and Moore 1 977, Howells 1 985, Marwitz 

 1986). They are usually found in organic-stained 

 brackish waters that can be either stagnant or flowing 

 (Randall 1959, Wade 1962, Rickards 1968) in depths 

 of 1 .5 to 1 5 m (Simpson 1 954, Randall 1 959, Rickards 



1968, Wade 1969, Franks 1970). Tarpon 305 to 487 

 mm are common in headwaters of brackish and fresh- 

 water streams. Movement to deeper rivers, canals, 

 pools, lakes, and eventually to the ocean occurs as 

 they grow larger (Hildebrand 1 963, Wade 1 969) At this 

 time, they are found in waters 0.9 to 2.5 m deep (Gunter 

 1 945, Tabb and Manning 1 961 , Rickards 1 968, Wade 



1969, Franks 1970). Adults are primarily found in 

 coastal inshore waters, inlets, estuaries, and passes 

 between islands, but they also occur in deeper rivers, 

 canals, streams, and lakes (Breder 1944, Hildebrand 

 1963, Wade 1969, Kushlan and Lodge 1974, Hoese 

 and Moore 1 977, Loftus and Kushlan 1 987) in fresh to 

 euhaline salinities (Breder 1944, Randall 1959, Tabb 

 et al. 1962, Kushlan and Lodge 1974, Loftus and 

 Kushlan 1 987). Adults are found over a wide variety of 

 water depths that range from shallow waters to deep 

 (90-1400 m) offshore spawning sites (Killam et al. 

 1 992). In summer, they have been reported in offshore 

 areas such as coral reefs as far as 70 miles west of Key 

 West, Florida, in the Dry Tortugas National Park 

 (Schmidt pers. comm.). 



Caldwell 1 955, Randall 1 959, Tabb and Manning 1 961 , 

 Wade 1962, Rickards 1968, Franks 1970, Marwitz 

 1 986). Loss of equilibrium or death has been observed 

 from 9.5° to 1 8.2°C in vitro with the greatest occurrence 

 at 1 4.0°C (Howells 1 985). Otherstudies report mortali- 

 ties occurring between 1 2° to 1 4°C and 1 2° to 1 6°C for 

 sudden cold snaps, but resistance to cold might be 

 greater during slow temperature falls (Tabb and Man- 

 ning 1961, Rickards 1968). 



Salinity - Eggs and Larvae: Stage I larval specimens 

 have been collected from waters at 28.5 to 39%o (Wade 

 1962, Smith 1980, Zale and Merrifield 1989, Crabtree 

 et al. 1 992), and it is assumed that eggs require similar 

 conditions for proper development (Zale and Merrifield 

 1 989). Early larvae (Stage I) are possibly stenohaline, 

 seeming to prefer high salinities as they are generally 

 not found in low or fluctuating salinities, and probably 

 stay well offshore until the approach of metamorphosis 

 (Smith 1980). 



Salinity - Juveniles and Adults: All developmental 

 forms except Stage I larvae are euryhaline. They have 

 been recorded from 0.0 to 47%o, but seem to prefer 

 salinities between 5.1 and 22.3%o (Gunter 1945, 

 Simpson 1954, Odum and Caldwell 1955, Gunter 

 1956, Simmons 1957, Randall 1959, Tabb and Man- 

 ning 1961, Harrington 1966, Rickards 1968, Wade 

 1969, Franks 1970, Tagatz 1973, Tucker and Hodson 

 1976, Marwitz 1986). 



Substrate : Juveniles and adults are generally found 

 over soft mud bottoms that sometimes contain hydro- 

 gen sulfide; but, they also occur over sand, firm mud, 

 sandy mud with no vegetation, and peat (Gunter 1 945, 

 Simpson 1954, Randall 1959, Tabb and Manning 

 1961, Tabb et al. 1962, Rickards 1968, Wade 1969, 

 Franks 1970). 



Physical/Chemical Characteristics : 

 Temperature - Eggs and Larvae: The physical and 

 chemical requirements of tarpon are not completely 

 known. Stage I larval specimens have been collected 

 from waters at 22.2° to 30.0°C (Wade 1962, Smith 

 1980, Zale and Merrifield 1989, Crabtree et al. 1992), 

 and it is assumed that eggs require similar conditions 

 for proper development (Zale and Merrifield 1989). 

 They appear to prefer warmer waters (Jones et al. 

 1 978). Stage II larvae have been recorded in tempera- 

 tures ranging 19.8° to 30.8°C (Tagatz 1973, Tucker 

 and Hodson 1976). Stage III larvae have been col- 

 lected in waters 25° to 27°C (Harrington 1966). 



Temperature - Juveniles and Adults: The known tem- 

 perature ranges are similar for both juveniles and 

 adults (Wade 1962). They have been recorded from 

 16° to 40°C (Gunter 1945, Simpson 1954, Odum and 



Turbidity: Stage I larvae only occur in clear offshore 

 waters (Zale and Merrifield 1989). In subsequent life 

 history stages, the tarpon appears to be tolerant of high 

 turbidities. 



Dissolved Oxygen: Tarpon have been considered to 

 be obligate air breathers (Wade 1 962), able to breathe 

 by means of rolling and gulping air which is held in a 

 highly vascularized air bladder (Odum and Caldwell 

 1955, Wade 1969). However, more recent evidence 

 suggests that they are not obligate air breathers and 

 can survive at least two weeks without air breathing in 

 well oxygenated water (Killam et al. 1992). Larvae 

 have been observed to die if prevented from surfacing 

 as larger fish do (Harrington 1 966). Their air breathing 

 capability allows them to survive in waters with a 

 dissolved oxygen content as low as 0.00 to 0.81 parts 

 per million (Odum and Caldwell 1955). 



Movements and Migrations : Leptocephalus larvae are 

 probably transported into estuaries by tidal currents 

 (Killam et al. 1 992). In the Everglades, tarpon are able 

 to move between bodies of water during high water 

 periods, resulting in their occurrence in isolated ponds 

 (Loftus and Kushlan 1987). As juvenile tarpon grow, 

 they move from nursery grounds to deeper inshore 



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