Code goby, continued 



frequent warming periods. Variations in spawning 

 behavior are possibly due to the different temperature 

 patterns found throughout the range of this species 

 (Dawson 1966, Dokken et al. 1984). Temperatures 

 greater than 19°C may be necessary for spawning to 

 occur, but repression has been noted at temperatures 

 greater than 30°C in Florida populations (Springer and 

 McErlean 1 961 , Dokken et al. 1 984). Spawning occurs 

 during falling salinities (<45%o) in Texas (Dokken et al. 

 1984) and from 19.2 to 23.0%o in Florida populations 

 (Springer and McErlean 1961). Eggs are usually 

 attached to the underside of shells or sponges and are 

 guarded by males (Breder 1942). 



Fecundity : Both left and right ovaries ripen equally with 

 approximately equal numbers of eggs. In Tampa Bay, 

 a 27 mm standard length (SL) female was reported with 

 349 eggs in the right ovary, and 346 eggs in its left. The 

 number of eggs produced appears to be related to the 

 size of the female with 56 per ovary observed in a 15 

 mm SL fish and 397 per ovary observed in a 28 mm SL 

 fish. Eggs are apparently spawned in toto, but two 

 spawnings per season are considered possible 

 (Springer and McErlean 1961). 



Growth and Development 



Egg Size and Embryonic Development : Ovarian eggs 

 are transparent until a diameter of 0.102-0.136 mm is 

 attained, and then they become more opaque. Eggs 

 are ripe at 0.476-0.782 mm (Springer and McErlean 

 1961). Fertilized eggs are elliptical, opaque, slightly 

 yellowish with a clear envelope. Their length varies 

 from 1 .30-1 .40 mm in June to 1 .55-1 .70 mm in March, 

 while width varies from 0.50 mm in June to 0.60-0.70 

 mm in March (Breder 1 942, Fritzsche 1 978). Eggs are 

 fastened by filaments attached to the chorion at the 

 germinal end, and have an opaque, slightly yellowish 

 yolk with a widely variable number of oil droplets 

 scattered over its surface (Springer and McErlean 

 1961, Fritzsche 1978). In fertilized eggs of unknown 

 age collected on March 14, near Charlotte Harbor, 

 Florida, the head was large and prominent 22.25 hours 

 after collection. After another 26.25 hours, the embryo 

 formed, somites were visible after another 41. 25 hours, 

 and the heart was visible and beating after another 

 27.5 hours. Total observation period covered 117.25 

 hours with the embryos dying before hatching (Breder 

 1942, Fritzsche 1978). 



Age and Size of Larvae : Little information is available 

 on the larval stage of this species. 



Juvenile Size Range : Described specimens of juvenile 

 code goby are 5.6 to 8.78 mm SL (Shropshire 1932, 

 Springer and McErlean 1961). All fin elements are 

 present by 5.6-8.5 mm SL (Springer and McErlean). 

 Increase in pigmentation, appearance of tubular nos- 



trils and a series of rows of papillae on lower jaw, 

 forehead, and cheeks occur by 8.78 mm SL (Shrop- 

 shire 1932). Growth rate is moderate with 0-class fish 

 reaching 26.9 to 28.4 mm total length (TL) by the end 

 oftheirfirstyear(SpringerandWoodburn 1960, Dawson 

 1966). 



Age and Size of Adults : Young of the year can achieve 

 sexual maturity when only a few months old. Minimum 

 sizes noted for sexually mature adults are 13.1 mmTL 

 and 14.6 mm SL for females (Springer and McErlean 

 1961, Dawson 1966), and 16.5 mm TL for males 

 (Fritzsche 1978). Maximum reported sizes are 31.5 

 mm TL for females (Dawson 1 966), and 44 mm SL for 

 males with males being larger on the average than 

 females (Springer and McErlean 1961). Maximum 

 reported size for this species is 55.5 mm TL or 45.0 mm 

 SL for an unsexed fish (Ginsburg 1933). The code 

 goby is considered an annual fish with very few indi- 

 viduals living over one year, although some males are 

 reported to live up to 2 years (Springer and McErlean 

 1961). 



Food and Feeding 



Trophic mode : The code goby is a small benthic 

 predator. 



Food Items : Code gobies feed principally on amphi- 

 pods, mysids, chironomid larvae, decapod shrimp, 

 copepods, isopods, gamarids, cladocerans, ostracods, 

 small molluscs, and some algal filaments and detritus 

 when 15 to 35 mm SL (Reid 1954, Springer and 

 Woodburn 1 960, Odum 1 971 ). Smaller individuals, 7- 

 15 mm SL, have been found to eat harpacticoid 

 copepods, juvenile mysids, cumaceans, and many 

 penate diatoms (Odum 1971). 



Biological Interactions 



Predation : Reported predators include inshore lizardfish 

 (Synodus foetens), spotted seatrout, and gray snapper 

 (Springer and Woodburn 1960, Tabb and Manning 

 1961, Thayer et al. 1987). 



Factors Influencing Populations : The size and abun- 

 dance of seagrass beds and drift algae biomass may 

 affect the abundance of the code goby by providing 

 both habitat and refuge for this species (Kulczycki et al. 

 1981). 



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