Striped mullet, continued 



Salinity - Larvae: Larvae are stenohaline at hatching 

 and become increasingly euryhaline with size (Nordlie 

 et al. 1982). Early larvae are poly- to euhaline in 

 salinities from 26 to 35%> and are unable to tolerate 

 fresh water. Older larvae are able to tolerate salinities 

 from 16 to 36.5%o with reported optimal ranges being 

 32 to 33%o and 26 to 28%o (Kuo et al. 1 973, Sylvester 

 et al. 1 975, Finucane et al. 1 978, Ward and Armstrong 

 1980, Nordlie et al. 1982). Ditty and Shaw (1996) 

 collected 1,983 larval mullet in the northern Gulf of 

 Mexico, at salinities ranging from 23.5 to 36.8%o, with 

 a mean of 23.4%o. By the pre-juvenile stage, osmotic 

 regulatory abilities and salinity tolerances reach a 

 definitive state, and the mullet becomes euryhaline 

 (Nordlie et al. 1982). Pre-juveniles have been re- 

 corded from a range of to 54%o with a preference for 

 <1 to 40%o (Gunter 1 945, Swingle 1 971 , Christmas and 

 Waller 1973, Ward and Armstrong 1980). 



Salinity - Juveniles and Adults: Both juveniles and 

 adults are euryhaline with similar tolerances. They 

 have been observed in salinities ranging from 0.0 to 

 75%o, but adults appear to prefer median salinities of 

 approximately 26%o, and juveniles range from 20 to 

 28%o (Gunter 1 945, Kilby 1 949, Simmons 1 957, Hoese 

 1960, Renfro 1960, Hellier 1962, Perret et al. 1971, 

 Dunham 1972, Christmas and Waller 1973, Swingle 

 and Bland 1974, Pineda 1975, Tarver and Savoie 

 1976, Finucane et al. 1978, Martin and Drewry 1978, 

 Ward and Armstrong 1980, Cornelius 1984). The 

 capability to tolerate salinities ranging from to 35%o 

 appears when individuals have reached a standard 

 length (SL) of 40-69 mm and are 7.5-8.5 months old 

 (Nordlie et al. 1982). 



Dissolved Oxygen (DO): Eggs and larvae prefer higher 

 concentrations of oxygen (about 4 mg/l) and are not 

 able to tolerate ranges as low as juveniles and adults 

 can (Ward and Armstrong 1 980, Cech and Wohlschlag 

 1 982). Two possible mechanisms for tolerance to low 

 oxygen levels have been examined. Enhanced hemo- 

 globin concentrations found in striped mullet would 

 enable it to meet seasonally heavy oxygen demands 

 during the warmest months and the autumn spawning 

 period (Cech and Wohlschlag 1982). Aerial respiration 

 in the upper posterior portion of the pharynx using air 

 obtained by jumping, rolling, or holding the head aboye 

 water and moving air into the upper pharyngeal cham- 

 ber may also provide supplementary oxygen for respi- 

 ration (Hoese 1985). 



Movements and Migrations : The striped mullet gener- 

 ally does not make long migrations. Movements are 

 predominantly inshore-offshore and occur during fall 

 and winter when large schools leave bays and estuar- 

 ies in order to spawn in offshore Gulf waters. After 

 spawning, adults return to inshore habitats. Most 



striped mullet move less than 33 km from their spawn- 

 ing site (Kilby 1949, Broadhead 1953, Broadhead and 

 Mefford 1956, Moe 1972, Hoese and Moore 1977, 

 Ward and Armstrong 1980). However, a tagging study 

 conducted in Florida Bay and along the west coast of 

 Florida showed a northwesterly coastwise movement, 

 especially during the spawning season, with one indi- 

 vidual recaptured 500 km from where it was released 

 (Funicelli et al. 1989). One study found that a prefer- 

 ence existed for bay waters and suggested an organic 

 compound present in these waters may guide mullet 

 back to their native area (Kristensen 1 964). At lengths 

 of 16 to 20 mm SL (40 to 45 days old), pre-juveniles 

 migrate to inshore and estuarine waters in the spring 

 months. Entry of juveniles into estuarine areas begins 

 in November, and continues through February (Ditty 

 and Shaw 1996). After entering bay systems from 

 offshore waters, they migrate to nursery areas which 

 are thought to be secondary and tertiary bays. Most 

 juveniles spend the end of their first year in these 

 coastal waters, salt marshes, and estuaries, and over- 

 winter in deeper parts of these areas. However, some 

 migrate offshore during the fall as sub-adults to mature 

 and spawn when colder temperatures set in (Henley 

 and Rauschuber 1981, Collins 1985). Movement of 

 mullet is otherwise random and usually restricted to a 

 broad coastal area (Broadhead 1953, Broadhead and 

 Mefford 1956, Broadhead 1958, Moe 1972). 



Reproduction 



Mode : This species has separate male and female 

 sexes (gonochoristic). Fertilization is external, by 

 broadcast of milt and roe into the water column. Devel- 

 opment is oviparous. There are occasional occur- 

 rences of hermaphrodites, but they are considered 

 atypical (Thomson 1966). 



Spawning : Spawning may begin in October to mid- 

 November and last until March. Peak spawning gen- 

 erally occurs from December through February in the 

 Gulf of Mexico, but there is regional variation. Peak 

 spawning in the northern Gulf of Mexico in November- 

 December, over or beyond the Continental Shelf at sea 

 surface temperatures >25°C (Ditty 1986, Ditty and 

 Shaw 1996). In Florida, the general spawning period 

 is from December to February, while off the Texas 

 coast, the spawning season usually extends from 

 October to December (Breder 1940, Gunter 1945, 

 Broadhead 1953, Reid 1955, Anderson 1958, Arnold 

 and Thompson 1958, Broadhead 1958, Arnold et al. 

 1 960, Christmas and Waller 1 973, Wagner 1 973, Moore 

 1974, Sabins and Truesdale 1974, Fahay 1975, 

 Finucane et al. 1 978, Ward and Armstrong 1 980). Ripe 

 adults collect in passes in large schools and migrate 

 offshore. The return of spent adults begins 10 days 

 later and continues until May (Gunter 1 945, Arnold and 

 Thompson 1958, Moore 1974, Sabins and Truesdale 



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