Striped mullet, continued 



Martin and Drewry 1 978). Fin morphology is the same 

 as that of adults (Martin and Drewry 1 978). The caudal 

 fin achieves its final form when the fish has a fork length 

 (FL) of 1 1 mm, and the scales change suddenly from 

 that of a prejuvenile to an adult when above 30 mm TL. 

 The circuli of the posterior (exposed) region become 

 complete and less densely packed than those of ante- 

 rior region. Lateral stripes are generally like those of 

 adults, becoming increasingly distinct from 44 to 60 

 mm SL (Martin and Drewry 1978). 



Age and Size of Adults : The life span for the striped 

 mullet is up to 7 years for males, and 8 years for 

 females (Martin and Drewry 1 978, Ward and Armstrong 

 1980) with a probable average life span of about 5 

 years (Hellier 1962), although a 13 year old fish has 

 been reported (Collins 1985). Adults grow at a rate of 

 38-64 mm per year (Broadhead 1953). The recorded 

 size range for adults in the study area is 200 to 760 mm 

 TL (Kilby 1949, Breuer 1957, Hellier 1962, Franks 

 1970, Perret et al. 1971, Moore 1974, Pineda 1975, 

 Tarver and Savoie 1976, Hoese and Moore 1977, 

 Collins 1985). Average sizes for size classes 1 through 

 5 have been recorded in SL as 1 1 6 mm, 1 81 mm, 230 

 mm, 277 mm, and 324 mm with mean weight increases 

 of 31 g, 84 g, 1 1 6 g, and 1 67 g for the first through the 

 fourth year (Hellier 1 962). One weight recorded for a 

 238 mm SL fish was 345.0 g (Franks 1970). Adults 

 become reproductively mature at 3 years of age or 

 greater when they reach lengths of 200 to 255 mm TL 

 for males and 250 to 350 mm TL for females, or 230 mm 

 to 285 mm FL for males and 243 to 290 mm FL for 

 females (Gunter 1945, Broadhead 1953, Arnold and 

 Thompson 1 958, Moore 1 974). The weight of spawn- 

 ing females ranges from 600 to 1 400 g (Sylvester et al. 

 1975). Thomson (1966) has developed a Von 

 Bertalanffy equation to describe the growth of striped 

 mullet. 



Food and Feeding 



Trophic Mode : Larvae are carnivorous, with a diet 

 consisting of planktonic material that probably includes 

 microcrustaceans (Harrington and Harrington 1961, 

 Bishop and Miglarese 1978, De Silva 1980, Ward and 

 Armstrong 1980). Pre-juveniles change from carni- 

 vores to omnivores to herbivores as size increases. 

 The trophic transition begins at 15 mm SL and is 

 completed before metamorphosis, usually by 35 mm 

 SL. Feeding by juveniles and adults occurs littorally in 

 shallows by sucking up bottom surface material, strain- 

 ing it through an elaborate pharyngeal sieving mecha- 

 nism (Hiatt 1 944, Broadhead 1 958, Darnell 1 958, Tabb 

 and Manning 1961), and spitting filtered debris from 

 the mouth (Thomson 1966). Feeding occurs day and 

 night, and digestion is aided by a gizzard which grinds 

 up the tough food items ingested (Hiatt 1944, Broadhead 

 1958, Darnell 1958, Thomson 1966). Although chiefly 



herbivorous, striped mullet may opportunistically feed 

 on animal matter, especially in the fall when an above- 

 normal protein intake may be required for gonad matu- 

 ration (Bishop and Miglarese 1978). 



Food Items : The prejuvenile diet consists of plant 

 debris, algae (diatoms), copepods (eggs, nauplii, 

 adults), mosquito larvae, and fish residue (Harrington 

 and Harrington 1961). Juveniles and adults generally 

 prefer organic detritus, diatoms, filamentous algae, 

 organic matter, benthic organisms, plant tissue, fora- 

 minifera, and plankton of correct particle size, but they 

 have also been observed with fish scales, sponge 

 spicules, and minute gastropods in their stomach con- 

 tents (Hiatt 1 944, Broadhead 1 958, Darnell 1 958, Tabb 

 and Manning 1961, Moore 1974). Juvenile striped 

 mullet may feed on "marine snow", macroscopic sus- 

 pended aggregates of mixed mineral, detrital, algal, 

 and bacterial composition (Larson and Shanks 1996). 

 Mullet that graze on submerged sediments may filter 

 out and reject the coarser particles, and ingest the 

 smaller ones, which contain a higher proportion of 

 absorbed organic matter and adsorbed microorgan- 

 isms (Odum 1968b). In coastal Georgia, mullet have 

 been observed feeding on dinoflagellates during "red 

 tide" events (Odum 1968a). Adult striped mullet have 

 been observed actively feeding on a swarm of swim- 

 ming polychaetes, Nereis succinea (Bishop and 

 Miglarese 1978). 



Biological Interactions 



Predation : Piscine predators include: red drum, spot- 

 ted seatrout, hardhead catfish, southern flounder, bull 

 shark, alligatorgar(Lep/sosfeL/ssparu/a), and longnose 

 gar (L osseus) (Gunter 1945, Breuer 1957, Simmons 

 1957, Darnell 1958). Wading birds also prey upon this 

 species (Sogard et al. 1989). 



Factors Influencing Populations : An EPA study has 

 shown that crude oil may serve as a non-specific stress 

 agent that lowers resistance of mullet to disease 

 (Minchew and Yarbrough 1 977). It is also considered 

 possible that crude oil can act as a medium for patho- 

 genic bacteria growth, and adversely affect the zoop- 

 lankton serving as food for mullet. A number of 

 parasites have been isolated from mullet including: 

 nematodes, leeches, blood trypanosomes, ciliates, 

 spiny-headed worms, bacteria, protozoa, copepods, 

 and tapeworms (Reid 1 955, Overstreet 1 974, Paperna 

 1 975). There is concern that the expanding roe fishery 

 may result in overharvest of mullet populations in some 

 areas (Clement and McDonough 1997). 



310 



