|Spot croaker range map|
The spot croaker (Leiostomus xanthurus) or spot is a small saltwater fish species inhabiting estuary and coastal waters along the eastern coast of United States, Gulf of Mexico, and the Caribbean. The spot croaker derives its name from the prominent dark spot behind each gill. It is also known for the croaking sound it produces using its swim bladder. It is part of the family Sciaendae and the only species in its the genus, Leiostomus. Spot croakers spawn offshore and the spawn migrate inland to develop into juveniles. They are frequently caught by recreational anglers and make excellent table fare. Their diets consist largely of organic detritus, small crustaceans, and worms. Bloodworms are the ideal bait when fishing for spot croaker. The community of Hampstead, North Carolina hosts the North Carolina Spot Festival the last weekend of September to honor the fish.
Naming and taxonomy
Almost every common name for the spot croaker refers to the darkened "spot" above the gill cover of the mature individuals. The croaker part of the name comes the association to the loud croaking sound they produce with their swim bladders. The spot croaker is called simply a spot by most countries that have a coastline within their natural range.
The genus Leiostomus belongs to the family Sciaenidae. This family contains 270 species from 70 genera that live in fresh, brackish, and marine water environments. All members of the family Scianidae carry either croaker or drum of some sort in their name, because of the croaking sound they produce.
The spot croaker is a deep-bodied flat fish with an arched back. A large black spot is set above the upper edge of the gill cover. Its body color is gray-blue dorsally, fading to yellow ventrally. It also has a set of 12–15 darker streaks that run forward diagonally from the dorsal surface to about the middle of its body. These streaks often fade with age. The fins are pale yellow in color. The head is blunt with a small mouth. The upper jawbone extends to approximately the middle of the eye. There are no teeth in the lower jaw. The dorsal fin is almost continuous, with a dip separating the stiff dorsal spines from the soft rays. It has 9-11 dorsal spines and 29–35 soft rays. The anal fin has two spines and 12–13 rays. The caudal area is moderately deep, and the caudal fin is notched. A large black spot is set above the upper edge of the gill cover.
Being in the family Sciaenidae, the spot croaker has the ability to produce a croaking sound, the most recognizable auditory trait as its name suggests. The spot croaker uses sonic muscle fibers that run horizontally along its body, around its swim bladder, connected to a central tendon which runs ventrally around the swim bladder. The fish contracts its sonic muscle fibers against the swim bladder to produce the croaking sound. The swim bladder is used as a resonating chamber, which is more expansive and branched than the swim bladder of fishes not in the Sciaenidae family.
Range and behavior
The spot croaker is most commonly found between the Chesapeake Bay and South Carolina. It is also found along the Atlantic coast of the US, the Florida Keys, and the Gulf of Mexico, but in smaller populations. Rutgers University's 2013 fish stock report  indicates that spot croakers have become more numerous in New Jersey's waters. They inhabit coastal areas, no deeper than 60 m. This appears to be due to the tendency of Spot croakers to ascend in response to higher salinity concentrations which would be experienced in the lower depths. During the summer months, spot croakers inhabit shallower bays and estuaries and move out into the coastal waters during the winter months as the temperature drops; the northern populations also migrate south for the winter until the water warms up again.
Spot croakers are bottom feeders, and their diets consist of worms, mollusks, small crustaceans, and detritus. As they grow, the size of their prey increases. Predators of the spot croaker include striped bass, weakfish, summer flounder, bluefish, and various species of sharks.
Spot croakers populate the area along the Atlantic Coast, in both estuarine and coastal waters from Maine to Florida; the highest concentration are between the Chesapeake Bay and South Carolina. Spot croakers migrate seasonally, staying in bays and estuaries in the spring, until late summer when the move offshore to spawn. Spot croakers mature around the age of two or three, and grow seven to eight inches in length. They can live up to six years, although fish older than four are rare. Spawning takes place offshore from fall to early spring. The larvae have been known to hatch as far as 63 nautical miles offshore, but they migrate towards the coast and inhabit estuaries and inlets while they develop into juveniles. As they mature, spot croakers migrate toward higher-salinity areas.
The short lifespans of spot make their year-to-year fishing catches fluctuate greatly. With little population information, it cannot be concluded whether or not they are overfished, as well as their general health. Management of spot croakers will continue to be minimal in the regulations set forth.
At least one aquaculture project in New Jersey is attempting to culture spot croaker for potential commercial production.
- K., Hill (9 June 2005). "Leiostomus xanthurus (spot)". Smithsonian Marine Station. Retrieved 25 October 2011.
- Susan, Luna; Froese, Rainer (6 October 2010). "Leiostomus xanthurus Lacepède, 1802 Spot croaker". fish base. Retrieved 20 October 2011.
- "North Carolina Spot Festival". Retrieved 2008-12-04.
- "Croaker". destin fishing guide. Retrieved 14 November 2011.
- Froese, Rainer and Pauly, Daniel, eds. (2008). "Leiostomus xanthurus" in FishBase. May 2008 version.
- Froese, Rainer, and Daniel Pauly, eds. (2010). "Sciaenidae" in FishBase. october 2010 version.
- "spot". Chesapeake Bay Program. Retrieved 23 November 2011.
- Collin, Shaun; N. Justin Marshall (2003). Sensory processing in aquatic environments. New York: Springer-Verlag New York. p. 176. ISBN 0-387-95527-5.
- "Institute of Marine and Coastal Science | Home". marine.rutgers.edu. Retrieved 2014-01-24.
- De Vries, M.C.; Forward, R.B.; Hettler, W.F. (1995). "Behavioral response of larval Atlantic menhaden Brevoortia tyrannus (Latrobe) and spot Leiostomus xanthurus (Lacépède) to rates of salinity change". Journal of Experimental Marine Biology and Ecology 185 (1): 93–108. doi:10.1016/0022-0981(94)00137-3.
- Govoni, John J.; Ortner, Peter B.; Al-Yamani, Faiza; Hill, Leonard C. (1986). "Selective feeding of spot, Leiostomus xanthurus, and Atlantic croaker, Micropogonias undulatus, larvae in the northern Gulf of Mexico". Marine Ecology Progress Series 28: 175–83. doi:10.3354/meps028175. OCLC 4665755823. hdl:1969.3/21394.
- 2010 Maryland FMP Report Section 3.Atlantic croaker (Micropogonias undulates) and Spot (Leiostomus xanthurus). July 2011. pp. 1–5. Retrieved 9 January 2011.
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