Species Description: Eucinostomus gula is a member of the family Gerreidae. The Eucinostomus genus is distinguished from other members of the family Gerreidae by the interhaemal cone, an unusual cone-shaped structure formed from the first two anal pterygiophores that enclose the posterior end of the air bladder (Matheson and McEachran 1984).
The silver jenny is a small fish with a compressed body and protrusible mouth. It has the greatest body depth (38.5 to 45.5 % of the standard length) of the Eucinostomus sp. E. gula is a silvery fish that is lightly pigmented on its snout (Matheson and McEachran 1984).
Regional Occurrence: Eucinostomus gula occurs seasonally in the Chesapeake Bay and other estuaries south to Florida (Kerschner et. al. 1985), to Brazil (Godefroid et al. 2001), the Bahamas, West Indies and the Gulf of Mexico.
IRL Distribution: The silver jenny is common in the Indian River Lagoon during the warmer months and appears to keep to the interior of estuaries (Kerschner et. al. 1985, Godefroid et al. 2001). Schools of juveniles as opposed to adults are encountered more frequently in seagrass beds.
Age, Size, Lifespan: Individuals in the Indian River Lagoon range in size from 10 to 109 mm (Kerschner et al. 1985). The maximum length of Eucinostomus gula is reported to be 35 cm.
Abundance: Eucinostomus spp. are abundant, schooling fish that often dominate the transient (seasonal visitors) species in subtropical and tropical estuaries (Stoner 1986). In the Indian River Lagoon, schools of the Eucinostomus gula are recorded to make up 67% of the catch in the family Gerreidae (Kerschner et. al. 1985). In a Brazilian estuary at Pontal do Sul, Paraná, E. gula was reported to make up approximately 5 % of the larval and juvenile catch in January and February (Godefroid et al. 2001).
Reproduction: Eucinostomus gula appears to spawn year round, however the peak season is in the warmer summer months in Brazilian waters (Godefroid et al. 2001).
Embryology: Larval forms and juveniles of the silver jenny are found from December to June in water temperatures of 16-29°C and salinities ranging from 19-34 ppt, similar to the spotfin mojarra (Godefroid et al. 2001).
Trophic Mode: Eucinostomus gula is a benthic feeder using its highly protrusible mouth to forage for infaunal invertebrates. It feeds primarily on bivalves, crustaceans, ostracods, and amorphous debris (Kerschner et al. 1985, Bronco et al. 1997).
Fishery: Used as a minor bait fish.
Godefroid RS, Santos C, Hofstaetter M, and HL Spach. 2001. Occurrence of larvae and juveniles of Eucinostomus argeneus, Eucinostomus gula, Menticirrhus americanus, Menticirrhus littoralis, Umbrina coroides and Micropogonias furnieri at Pontal do Sul beach, Paraná. Brazilian Archives of Biology and Technology 44:411-418.
ITIS. Integrated Taxonomic Information System. Available online.
Kerschner BA, Peterson MS, and RG Gilmore, Jr. 1985. Ecotopic and ontogenetic trophic variation in mojarras. Estuaries 8:311-322.
Matheson RE, Jr. and JD McEachran. 1984. Taxonomic studies of the Eucinostomus argenteus complex (Pisces: Gerreidae): preliminary studies of external morphology. Copeia 4:893-902.
Rookery Bay Field Guide. PDF document available online.
Stoner AW. 1986. Community structure of the demersal fish species of Laguna Joyuda, Puerto Rico. Estuaries 9:142-152.