The common snook (''Centropomus undecimalis'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of marine

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Centropomidae of the order

Perciformes Perciformes (), also called the Percomorpha or Acanthopteri, is an order or superorder of ray-finned fish. If considered a single order, they are the most numerous order of vertebrates, containing about 41% of all bony fish. Perciformes means ...

. The common snook is also known as the sergeant fish or robalo. It was originally assigned to the sciaenid genus ''

Sciaena ''Sciaena'' is a genus of fish in the family Sciaenidae. They are native to Pacific, South America and Eastern Atlantic. Species There are currently 3 recognized species in this genus:Béarez, P. & Schwarzhans, W. (2013): ''Robaloscion'', a new ...

;'' ''Sciaena undecimradiatus'' and ''Centropomus undecimradiatus'' are obsolete synonyms for the species. One of the largest snooks, ''C. undecimalis'' grows to a maximum overall length of , but the common length is . The IGFA world record is 24.32 kg (53 lb 10 oz) caught in Parismina Ranch, Costa Rica, by Rafael Montalvo. Of typical centropomid form, it possesses drab coloration except for a distinctive black lateral line. It can also have bright yellow pelvic and

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s, especially during spawn.

General ecology

Reproductive ecology

The common snook is a protandric hermaphrodite fish species. Its spawning season appears to span from April to October, with the peak spawning occurring during July and August. Spawning typically occurs in near-shore waters with high

salinities Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

. Following the spawning period, the juveniles then migrate to the

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

s of the nearby estuarine environments. When these juveniles mature, they return to the higher-salinity waters of the open ocean to join the breeding population.

Habitat ecology

The common snook is an estuarine and freshwater-dependent fish species. Within estuaries, juvenile common snook are most often found inhabiting areas such as coastal wetland ponds, island networks, and creeks. Despite being a euryhaline species of fish, the common snook does show a tendency to gravitate towards lower-salinity conditions in the early stages of its life. By being able to adapt and thrive in both high- and low-salinity conditions through

osmoregulation Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration o ...

, common snook display a high level of habitat plasticity. Common snook are opportunistic predators whose feeding habits indicate a positive relationship between their size and the size of their prey, meaning that as the snook grows, it feeds on larger and larger prey. Common snook have been found to occasionally engage in cannibalism. This usually occurs during the winter when adults and juveniles are in close proximity to one another within their estuarine habitats. This form of cannibalism where the juveniles are fed on by the adults is referred to as intercohort cannibalism. The adult common snook that do cannibalize juveniles most likely target them because the juveniles may be the largest of the available prey, so are nutritionally efficient to prey upon.

Physiological ecology

Common snook, like many species of fish, are very in tune with their environments; even a slight change in their surroundings can have a significant impact on their behavior. For example, common snook are able to determine when to start and stop spawning based on the temperature and salinity of the water they inhabit, the amount of rainfall in the area, and whether or not the moon is full. However, in some cases, disturbances in their environment can have very negative effects on the snook population. One example is the devastating results of a

cold snap A cold wave (known in some regions as a cold snap, cold spell or Arctic Snap) is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in tem ...

. Snook are very susceptible to cold temperatures, with the effects ranging from the complete halt of all feeding at a water temperature of , to the loss of equilibrium at , to death at a temperature of . Recently, a cold snap in January 2010 resulted in a 41.88% decline in nominal abundance of the common snook population in southwest Florida from the previous year and a 96-97% decrease in apparent survival estimates.

Distribution and habitat

''C. undecimalis'' is widespread throughout the

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

waters of the western

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

from the coast of the

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

including the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

and the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

. Snook likely originated in Central America, and changes in the earth's climate brought the snook to Florida. During a great warming trend after the Ice Age, snook moved northward along the Mexico shoreline. They followed the perimeter of the Gulf of Mexico, along the west and east coasts of Florida. Massive snook are found in Central America, although they seem to look a little different because of the weather and water quality, but they are the same. No restrictions exist in most of Central America on the size or quantity of snook one can keep, consequently many locals have been keeping and killing these large snook for quite a while. Occurring in shallow coastal waters (up to in depth),

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...

and

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') ...

s, the fish often enter fresh water. They are carnivorous, with a diet dominated by smaller fishes, and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s such as shrimp, and occasionally crabs. Due to their limited cold tolerance, snook have been physiologically restricted from inhabiting temperate climates. In Florida, northern limits in their geographic range have historically been Tarpon Springs along the Gulf Coast and Cape Canaveral on the east coast. Over the past fifteen years, snook have extended their range as far north as the Suwannee River Estuary (~29°N), where an exponential increase in their population has been experienced. Warmer winter temperatures resulting from climate change have been suggested as a likely cause. There may also be potential food web effects, particularly for seatrout (''Cynoscion'' spp.), related to the snook colonization.

Human interest

Three

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

submarines have been named for this species, USS ''Robalo'' (SS-273) and USS ''Snook'' (SS-279) in the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

and USS ''Snook'' (SSN-592) in the 1950s. Considered an excellent food fish, the common snook is fished commercially and foreign-caught fish are sold in the US. When cooking snook, the skin must be removed, because it imparts an unpleasant taste, described as soapy, to the fish. Snook are also prized as

game fish Game fish, sport fish or quarry refer to popular fish pursued by recreational anglers, and can be freshwater or saltwater fish. Game fish can be eaten after being caught, or released after capture. Some game fish are also targeted commercial ...

, being known for their great fighting capabilities. The IGFA all-tackle world record for common snook stands at 53 lb 10 oz (24.32 kg) caught by Gilbert Ponzi near Parismina Ranch, Costa Rica. Previous world records were caught in Fort Myers, Florida, and Gatun Spillway Canal Zone, Panama. Anglers regularly use a variety of lures t
catch snook
Common lures include jerkbaits, bucktail jigs, topwater lures, spoons, and live bait.

Protection in Florida Gulf Coast

"At the June 2012 Florida Fish and Wildlife Conservation Commission (FWC) meeting, Commissioners voted to keep the recreational harvest of snook in Gulf of Mexico waters closed through Aug. 31, 2013. This closure will offer the species additional protection after a 2010 cold kill detrimentally affected the population. Snook closed to harvest in Gulf of Mexico and Atlantic waters in January 2010 after a severe cold kill affected snook population number." All snook were "catch-and-release only" in the Gulf of Mexico until August 31, 2013. At that time, the FWC could choose to open or close snook harvest for another season. The commercial harvest or sale of snook is prohibited by the same regulations. At the June 2013 FWC meeting, commissioners voted to let the recreational harvest of snook reopen in Gulf of Mexico waters from September 1 that year. The next stock assessment for snook was scheduled for 2015, but had not yet occurred as of June 2016, effectively leaving the fish under a protected status.

References

External links

* {{Taxonbar, from=Q1914539

common snook The common snook (''Centropomus undecimalis'') is a species of marine fish in the family Centropomidae of the order Perciformes. The common snook is also known as the sergeant fish or robalo. It was originally assigned to the sciaenid genus ...

Fauna of the Southeastern United States Fish of the Western Atlantic