Common Snook, Centropomus undecimalis
The Common Snook, Centropomus undecimalis, whose common Spanish name is robalo blanco and who is known locally as robalo, is a species in the Snook or Centropomidae Family, known collectively as robalos in Mexico. Globally, there are twelve species in the genus Centropomus, all twelve of which are found in Mexican waters and divided equally with six in the Atlantic and six in the Pacific.
The Common Snooks have oblong, slender, and compressed bodies. They are overall dull gray to yellowish-brown in color and transition to silvery ventrally. They have a prominent black mid-lateral line. Their fins vary in color from dusky to bright yellow. Their head profile is slightly concave. They have a sloping forehead, a protruding lower jaw, and a large mouth that extends to the center of their eyes. Their anal fin has a short base with 3 spines and 6 rays; their dorsal fin is high and divided with 8 or 9 spines and 10 rays; their pectoral fins have 15 or 16 rays; and their pelvic fins do not reach the anus. They have 18 to 24 gill rakers with 8 to 10 of these being found on their lower arch. They are covered with large rough scales.
The Common Snooks are a euryhaline species found near-shore in vegetative habitats including mangrove forests, beaches, shore reefs, river mouths, and salt marshes at depths up to 65 feet. They have a high tolerance for wide ranges of salinity and can be found in freshwater to estuarine to marine environments. Juveniles move from freshwater to salt marshes to seagrass beds as they develop. They also move northward as water temperatures increase. They prefer water temperatures between 25oC (77oF) and 31oC (88oF) and cannot survive if water temperatures go below 12.5oC (55oF) or above 39oC (102oC). They reach a maximum length of 1.40 meters (4 feet 6 inches). The current IGFA record is 24.3 kg (53 pounds 10 ounces) caught in Costa Rica waters. Females are generally larger than males. They are considered a top predator and are opportunistic carnivores that consume primarily small pelagic fish and supplement their diet with crustaceans including crabs and shrimps. They are preyed upon by dolphins, various birds, and larger fish on a limited basis. They are hermaphrodites and change from male to female at midlife with females being broadcast spawners twice a year. They have a lifespan of up to twenty years.
In Mexican waters the Common Snooks are found in all waters of the Atlantic.
The Common Snook is most likely confused with a series of other snooks from the Atlantic: the Largescale Fat Snook, Centropomus mexicanus (large second anal spine curving backwards), the Mexican Snook, Centropomus poeyi (very short second anal spine), the Smallscale Fat Snook, Centropomus parallelus (very stout second anal spine curving backwards), the Swordspine Snook, Centropomus ensiferus (golden-brown coloration; very long and large second anal spine), and the Tarpon Snook, Centropomus pectinatus (seven anal spines; very long and curved second anal spine).
The Common Snooks are the largest, most abundant, and widest ranging of the Atlantic snooks; they are heavily targeted as recreational game fish and are an esteemed food fish. They are favorites of both night fishermen and fly fishermen. Regulations in the southern United States and some Mexican states include seasonal closures, daily bag limits, length restrictions, and a ban on commercial fishing including the use of gill nets in Florida and Texas. They are sold commercially in the United States with fish being imported from Mexico. In general their populations are believed to have declined in the last 50 years due to overfishing, cold and warm weather episodes, red tides, and habitat degradation and destruction. They are late-maturing and long-lived fish and thus prone to overfishing. In Mexico, their fishery is currently considered to be at maximum sustainability and therefore at risk. However, from a conservation perspective this species is currently considered of Least Concern. They can also be found on a limited basis in some large public aquariums. Three US Navy submarines have been named after this species. Efforts to cultivate this species via aquaculture are currently under development and assessment.
Common Snook, Centropomus undecimalis. Fish caught from coastal waters off Anna Maria Island, Bradenton, Florida, March 2016. Length: 61 cm (24 inches). Weight: 9.1 kg (20.0 pounds). Catch, photo, and identification courtesy of George Brinkman, Guelph, Ontario, Canada.