Gulf killifish, continued 



Salinity - Eggs: Egg development has occurred from 

 to 80%° (Hubbs and Drewry 1959, Tatum et al. 1978, 

 Waas 1982, Perschbacher et al. 1990). The highest 

 hatching percentages occur from to 35%o 

 (Perschbacher et al. 1990). 



Salinity - Larvae: Best larval growth and survival occurs 

 in the 5 to 40%o range (Perschbacher et al. 1990). 

 Observations indicate a preference for lower salinity 

 waters ranging from 5 to 1 8.3%o (Gunter 1 950, Gunter 

 1967, Franks 1970, Swingle 1971, Christmas and 

 Waller 1 973, May 1977, Courtney and Couch 1984). 



Salinity - Juveniles and Adults: Both adult and juvenile 

 life stages are euryhaline, and have been found in 

 waters with salinities of 0.0 to 76.1 %o (Gunter 1945, 

 Gunter 1 950, Simmons 1 957, Reid 1 954, Hoese 1 960, 

 Gunter, 1967, Franks 1970, Swingle 1971, Wang and 

 Raney 1971, Christmas and Waller 1973, Wagner 

 1973, Pineda 1975, Swift et al. 1977, Tatum et al. 

 1978). 



Movements and Migrations : Reported movements have 

 been associated with feeding. The gulf killifish moves 

 onto marshes with flooding tides to feed, and returns on 

 the outgoing tide to tidal streams (Harrington and 

 Harrington 1961, Perschbacher and Strawn 1986, 

 Perschbacher et al. 1990), and shoreline flats (Reid 

 1 954). One study reports movement to deeper waters 

 during cold weather (May 1977). 



Reproduction 



Mode : This species has separate male and female 

 sexes (gonochoristic), and fertilization is external (Able 

 and Hata 1984). 



Spawning : Spawning occurs in estuaries in shallow 

 water among dense beds of marsh vegetation that are 

 typically flooded only during the bi-weekly high tides 

 (Simmons 1957, Harrington and Harrington 1961, 

 Greeley and MacGregor 1 983). Eggs are deposited in 

 clusters on submerged vegetation, plant roots, or on 

 the substrate itself (Waas 1982). Spawning periods 

 appear to be regulated primarily by temperature, with 

 photoperiod, food availability, tides, and circadian 

 mechanisms acting as indirect regulators (Tatum et al. 

 1978, Waas 1982, MacGregor et al. 1983, Waas and 

 Strawn 1 983, Hsiao and Meier 1 989). Spawning peaks 

 have been reported in spring, summer, and fall. A shift 

 in spawning season from early spring through summer 

 in the northern and western Gulf to the cooler late fall 

 through spring in south Florida is apparent with re- 

 corded seasons in the study area being: April-Septem- 

 ber in Corpus Christi Pass, Texas; March-June in 

 Copano and Aransas marshes, Texas (Gunter 1945); 

 April-May at Blackjack Peninsula, Texas (Gunter 1950); 

 March-April and August-September in Trinity Bay, 



Texas (Waas 1982); March-September in Mississippi 

 Sound, Alabama (MacGregor et al. 1 983); June-July in 

 Mobile Delta, Alabama (Swingle 1 971 ); late fall through 

 early spring in the Tampa Bay area (Springer and 

 Woodburn 1 960); and April-September at Cedar Key, 

 Florida (DeVlamingetal. 1978). Evidence also exists 

 of bimodal and year round spawning in some areas 

 (Gunter 1 945, Gunter 1 950, Kilby 1 955, Swingle 1 971 , 

 Ruebsamen 1972, Christmas and Waller 1973, 

 Subrahmanyam and Drake 1975, De Vlaming et al. 

 1 978, Waas 1 982, Waas and Strawn 1 983). Spawning 

 is apparently more prevalent in the evening than in the 

 day (Tatum et al. 1978). 



Fecundity : Gulf killifish are fractional spawners and 

 spawn many times per season (De Vlaming et al. 1 978, 

 Waas 1 982, Waas and Strawn 1 983). Usually 1 to 20 

 eggs are deposited per oviposition, but this species 

 has been found to have the potential to produce as 

 many as 1 200 eggs over a spawning season, with the 

 number of eggs correlated with length of the female 

 (Tatum 1978, Waas 1982, Waas and Strawn 1983). 

 Frequency of spawning is unknown and so actual 

 fecundity can not be determined, but one study con- 

 ducted over a period of 1 65 days (March through mid- 

 August) showed a daily deposition range of 0.01-1.18 

 eggs for females averaging 9.6 g (Tatum et al. 1982). 

 Other Fundulus species have been found to spawn 

 almost daily (Waas 1982, Waas and Strawn 1983). 



Growth and Development 



Egg Size and Embryonic Development : All growth and 

 development occurs within the estuary. Eggs are pale 

 yellow translucent spheres with vacuoles concentrated 

 at one pole. The color of fertilized eggs changes from 

 yellow to gray as the embryos develop. Eggs are 

 relatively large and range in size from 1 .0 to 2.1 mm in 

 diameter, averaging approximately 2.0 mm (Tatum et 

 al. 1978, Tatum et al. 1982, Waas 1982, Waas and 

 Strawn 1983). Embryonic development is oviparous 

 with egg hatching determined by incubation tempera- 

 ture (Courtney and Couch 1984). Hatching has been 

 observed at 9 to 1 4 days after fertilization at 26 to 31 °C 

 and 30%o, 1 4 to 28 days at 1 2.5 to 33°C and 5 to 1 0%o, 

 15 to 28 days at 12.5%o, and 21 days at 20°C (Hubbs 

 and Drewry 1959, Ernst and Neff 1977, Tatum et al. 

 1978, Tatum et al. 1982, Waas 1982, Courtney and 

 Couch 1984). Moderate salinities do not appear to 

 affect development and growth. Eggs may be able to 

 withstand exposure to air, an adaptation to fluctuating 

 water levels in coastal marshes (Loftus and Kushlan 

 1987). 



Age and Size of Larvae : Little information is available 

 on the age and size of gulf killifish larvae. 



178 



