Gulf flounder, continued 



cided with temperatures around 16°C. Beginning in 

 late spring to early summer, the adults and juveniles 

 return to the estuarine habitats (Reid 1954, Springer 

 and Woodburn 1960, Stokes 1977). 



Reproduction 



Mode : This species has separate male and female 

 sexes (gonochoristic). Fertilization is external, by 

 broadcast of milt and roe into the water column. The 

 eggs float at or near the surface of the water, and 

 development is oviparous (Gilbert 1986). 



Spawning : Spawning occurs during late fall and early 

 winter (November to February) in marine neritic waters 

 (Ginsburg 1952, Reid 1954, Springer and Woodburn 

 1960, Topp and Hoff 1972, Stokes 1977). Larvae of 

 Paralichthys species are known to occur in the north- 

 ern Gulf of Mexico from September through April, with 

 a peak from December to February (Ditty et al. 1 988). 



Fecundity : Little information on gulf flounder fecundity 

 is available (Gilbert 1986). 



Growth and Development 



Egg Size and Embryonic Development : Eggs are 

 spawned oviparously. Eggs are spherical, with an 

 approximate mean diameter of 0.87 mm, and one oil 

 globule with an approximate diameter of 0.18 mm 

 (Powell and Henley 1995). 



Age and Size of Larvae : Recently-hatched larvae are 

 approximately 2.0 mm notochord length (NL) (Powell 

 and Henley 1 995). Larvae appear in the eastern Gulf 

 of Mexico from December through early March (Reid 

 1 954, Topp and Hoff 1 972). The standard length (SL) 

 of postlarvae ranges 7-10 mm SL, and averages 8.4 

 mm (Deubler 1958). A full complement of fin rays is 

 present by approximately 8.5 mm SL (Powell and 

 Henley 1 995). In general, at any given size, larval gulf 

 flounder (P. albigutta) are further developed than south- 

 ern flounder (P. lethostigma) (Powell and Henley 1 995). 

 There are differences in pigmentation patterns be- 

 tween the two species, but these may be difficult to 

 discern with field-collected specimens. 



Juvenile Size Range : The growth rate of juveniles up to 

 a size of 50 mm appears to be rapid (Reid 1 954), and 

 size-at-age is highly variable for this species (Fitzhugh 

 pers. comm.). Stokes (1977) calculated total length 

 (TL) growth rates of males and females. Males during 

 their first year (age 0) ranged in size from 10 to >300 

 mm TL, and had an upper weight of 1 50 g, while those 

 in their second year (age I) ranged 221-350 mm in size 

 with an upper weight of 270 g. In first year females 

 sizes ranged from 10 to 400 mm TL, with an upper 

 weight of 270 g. Maturation occurs around 1 45 mm SL 

 for females (Topp and Hoff 1 972), and 50% of females 



are mature by age I (Fitzhugh pers. comm.). 



Age and Size of Adults : Stokes (1977) noted ripe 

 females were two years old and stated that females 

 grow more rapidly and attain greater sizes than males. 

 Females during their second year range in size from 

 291 to>400mm, and have an upper weight of 0.57 kg. 

 Third year females have a size range of 361-420 mm 

 TL and an upper weight of 1.01 kg. The maximum 

 reported size is 71 mm TL with a weight of 5 kg (Topp 

 and Hoff 1972). Actual life spans probably exceed 

 three years (Manooch 1 984). Females may live up to 

 seven years, and males up to four years (Fitzhugh 

 pers. comm.). Length-weight relationships for North 

 Carolina gulf flounder have been determined by Safrit 

 and Schwartz (1988). 



Food and Feeding 



Trophic mode : The gulf flounder is a benthic carnivore. 



Food Items : Small juveniles, 10-50 mm TL, feed pre- 

 dominantly on invertebrates; mostly crustaceans, es- 

 pecially mysids and amphipods. Juveniles above 45 

 mm consume both small fish and crustaceans, includ- 

 ing penaeid shrimp and portunid crabs. At 100-150 

 mm TL they are primarily piscivorous. Noted prey 

 include menhaden, bay anchovy and other anchovy 

 species, inshore lizardfish (Synodusfoetens), longnose 

 killifish (Fundulus similis), pipefishes, grunts, pigfish 

 {Orthopristis chrysoptera), pinfish, Atlantic croaker, 

 mullets, and code goby (Gobiosoma robustum) as well 

 as a number of unidentified forms (Reid 1 954, Springer 

 and Woodburn 1960, Topp and Hoff 1972, Stokes 

 1977, Benson 1982). 



Biological Interactions 



Predation : Information on predation of flounder is scarce. 

 Juveniles are probably the most susceptible to preda- 

 tion due to their smaller size. Known and suspected 

 species that prey on flounder species in the Gulf of 

 Mexico are: tigershark (Ga/eocerdo cuwer),gafftopsail 

 catfish (Bagre marinus), inshore lizard fish (Synodus 

 foetens), various searobins (family Triglidae), various 

 sculpins (family Cottidae),jewfish (Ep/nep/ie/us/fa/ara), 

 and larger-sized southern flounder (Kemp 1 949, Miles 

 1949, Dieneretal. 1974, Tanaka et al. 1989). 



Factors Influencing Populations : Paralichthys 

 lethostigma and P. albigutta are very difficult to distin- 

 guish from each other during the larval stage (Woolcott 

 et al. 1968). Early stages are often summarized as 

 "Paralichthys species" (King 1 971 , Ditty et al. 1 988) or 

 just "southern flounder" (Stokes 1 977). Adult southern 

 flounder generally outnumber gulf flounder in the north- 

 ern Gulf of Mexico, and catches containing the two 

 species are not usually separated. This makes catch 

 data forthe two species difficult to analyze. The shrimp 



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