Spotted Seatrout

Cynoscion nebulosus

Despite their name, these are not trout, but are in the drum fish family, named from the croaking, drumming noise they can make. The spotted seatrout have elongated, silvery bodies with irregular black spots on the upper half, and can grow to 39 inches long. They live in seagrass and shallow sandy sea bottoms, venturing into brackish estuaries and up freshwater rivers during cold seasons. They eat crustaceans and small bony fish, lunging at their prey and taking them with long canine teeth and swallowing them whole.

Order: Perciformes
Family: Sciaenidae
Genus: Cynoscion
Species: nebulosus

Common Names

English language common names include spotted seatrout, seatrout, speckled seatrout, spotted squeteague, spotted trout, and spotted weakfish. Other common names include acoupa pintade (French), corvina (Spanish), corvinata pintada (Spanish), corvinata-pintada (Portuguese), curvina (Spanish), gefleckter umberfisch (German), kulbiniec plamiasty (Poland), plettet skørfisk (Danish), plettet trommefisk (Danish), pyatnistyi gorbyl’ (Russian), and trucha de mar (Spanish).

Importance to Humans

The spotted seatrout is considered important in recreational and commercial fisheries in the Gulf of Mexico. Due to their habitat preference for marshes and estuaries, most of these fish are taken in state waters. Limited commercial harvest occurs in the waters of Louisiana, Mississippi, and Florida while this fish has been categorized as a gamefish in Texas and Alabama.

The flesh of the spotted seatrout has excellent flavor and texture for human consumption. It is often utilized fresh for steaming, broiling, and baking. Upon landing of this fish, it should be placed on ice as quickly as possible since the flesh loses quality rapidly if not kept chilled. Landed seatrout often have “spaghetti” worms embedded in the flesh (see parasite section for more information). These worms cannot survive in humans due to its host specificity, so while there is no harm in eating worm-infested seatrout flesh, they can be easily removed during filleting to make it more appealing.

Conservation

The spotted seatrout is not listed as endangered or vulnerable with the World Conservation Union (IUCN). The IUCN is a global union of states, governmental agencies, and non-governmental organizations in a partnership that assesses the conservation status of species.

> Check the status of the spotted seatrout at the IUCN website.

Geographical Distribution

With a range limited to the western Atlantic Ocean, the spotted seatrout is found from Cape Cod, Massachusetts to southern Florida and throughout the entire Gulf of Mexico.

Habitat

The spotted seatrout is a demersal fish that is found in brackish to marine water. It has been observed in shallow coastal and estuarine waters over sandy bottoms and seagrass to depths of 33 feet (10 m). This euryhaline fish also resides in salt marshes and tidal pools of salinities up to 75‰ (parts per thousand).

During the warm summer months, spotted seatrout associate with seagrass beds, moving to deeper pockets of water in estuaries during the cooler months. They rarely migrate far from estuaries where they are spawned.

Biology

Distinctive Features
The spotted seatrout has an elongate, somewhat compressed body with a slightly elevated back. The head is long with a pointed snout and large oblique mouth. The dorsal fin is continuous or slightly separate. The fins are scaleless with the exception of 1-10 rows of small scales at dorsal and anal fin bases. The lateral line extends onto the tail which is a characteristic of all Sciaenids.

This fish may be confused with others of its genus, especially the weakfish, C. regalis. However, the spotted seatrout has a distinctive pattern of black spots scattered along the upper body and extending into the caudal and dorsal fins. This coloration distinguishes the spotted seatrout from C. regalis and other members of Cynoscion.

Coloration
The body of the spotted seatrout is silvery with irregular black spots on the upper half, from the dorsal to the caudal fin. The dorsal side is dark gray with bluish reflections while the ventral side is silvery to white. The dorsal fin is dusky while other fins pale are to yellowish in color. There is a black margin on the posterior edge of the caudal fin.

Dentition
The upper jaw of the spotted seatrout contains a pair of large canine-like teeth with the lower jaw consisting of an enlarged inner row of closely set teeth. There are no teeth on the vomer, palatines, or tongue.

Size, Age, and Growth
The spotted seatrout grows to a maximum length of 39 inches (100 cm) TL (total length) and a maximum weight of 17.5 pounds (7.9 kg). Males reach sexual maturity at approximately 2 years of age – 7.9-9.4 inches (20-24 cm) standard length (SL), while females mature at 3 years of age – 8.3-9.8 inches (21-25 cm) SL. The expected life span of this species is 8-10 years.

Food Habits
Newly hatched spotted seatrout are planktivores, feeding primarily on copepods. As spotted seatrout grow, there is a dietary shift to larger items including mysids and shrimp. The diet of mature spotted seatrout consists of fishes and crustaceans. Prey species include anchovies, pinfish (Lagodon rhomboides), silversides (Menidia peninsulae), mullet (Mugil cephalus), croaker (Micropogonias undulatus), menhaden (Brevoortia tyrannus), silver trout, snapper, gobies, sheepshead (Archosargusprobatocephalus), grunts, toadfish, mojarras, and the occasional seatrout. Adult spotted seatrout swim in small schools with incoming tides and move into shallow areas to feed. Seatrout are ambush predators, making short lunges to grab prey with their front canine teeth prior to swallowing it whole.

Reproduction
Spawning activity, controlled primarily by temperature and salinity, peaks in the spring and late summer within the Everglades region in Florida. Along the gulf coast of Florida, spawning occurs from late March to September with a peak during June through August. Unimodal or bimodal spawning activity peaks vary temporally and geographically.

Spawning occurs during the nighttime hours and is signified by the croaking sounds made by males occurring one to two hours prior to sunset. Shallow bays and lagoons as well as deeper channels and depressions close in proximity to grass flats are utilized as spawning locations by the spotted seatrout. Spawning behavior includes a lot of jumping as well as side to side body contact among individuals.

Fecundity increases with size, with each female producing 15,000 to 1,100,000 eggs per spawning event. Spotted seatrout eggs are spherical, measuring approximately 0.70-0.98 mm in diameter, with one to four oil droplets. Eggs are either demersal or pelagic, depending upon salinity. At higher salinities, the eggs are more buoyant, but sink as salinity decreases below 25 parts per thousand (ppt). Optimum salinity for survival of eggs and larvae is approximately 28 ppt.

Larvae hatch about 18 hours after fertilization and associate with bottom vegetation or shell rubble. These newly hatched larvae measure 1.3-1.6 mm in length when hatched in laboratory settings. At 6-8 weeks of age (25-50 mm in length), the young spotted seatrout often form schools of up to 50 individuals. Juveniles move to seagrass beds, sandy bottoms, muddy bottoms, oil platforms, and shell reefs where they continue to live as adults.

Predators
Predators of the spotted seatrout include alligator gar (Lepisosteus spatula), striped bass (Morone saxatilis), Atlantic croaker (Micropogonias undulatus), tarpon (Megalops atlanticus), and barracuda (Sphyraena barracuda). Other predators include cormorants, brown pelicans, porpoises, and sharks.Parasites
Parasites associated with the spotted seatrout include various isopods, copepods, protozoans, flatworms, and tapeworms. The common worms found in the muscle tissue of seatrout, known as “spaghetti worms”, are the pleurocercoid stage of a tapeworm. Anglers sometimes avoid eating the flesh of infested spotted seatrout, however there have been no reports of any ill effects suffered from eating infested seatrout.

Taxonomy

This fish was originally named Otolithus nebulosos (Cuvier 1830). The currently valid name is Cynoscion nebulosus (Cuvier 1830). Only one synonym for this species appears in past scientific literature, Otolithus carolinensis Valenciennes 1833.

Prepared by: Cathleen Bester