Gulf sturgeon | |
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Gulf sturgeon on side | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Acipenseriformes |
Family: | Acipenseridae |
Genus: | Acipenser |
Species: | |
Subspecies: | A. o. desotoi |
Trinomial name | |
Acipenser oxyrinchus desotoi |
The Gulf sturgeon (Acipenser oxyrinchus desotoi) is a subspecies of sturgeon that lives in the Gulf of Mexico and some rivers draining into it. The Gulf sturgeon was first recognized as a separate subspecies in 1955. The nominate subspecies is the Atlantic sturgeon, A. o. oxyrinchus. [5] The Gulf sturgeon is listed as threatened under the United States Endangered Species Act, having been listed in 1991. [2] [3] Critical habitat, reflecting the range of the subspecies deemed essential for its continued survival, has been designated (see map). [6] The historical range is thought to have been from the Suwannee River on the western coast of Florida to the Mississippi River, and marine waters of the central and eastern portions of the Gulf of Mexico. Three sturgeon species in genus Scaphirhynchus share river territory with the Gulf sturgeon; none of the other sturgeon species is anadromous. [7]
Visually, Gulf sturgeon are almost impossible to differentiate from Atlantic sturgeon, as the most significant morphological difference is the spleen length, which is internal. Gulf sturgeon have a spleen length averaging 12.3% of their fork length, while Atlantic sturgeon have a spleen length averaging 5.7% of their fork length. Lesser morphological differences include relative head length, shape of dorsal scutes, and pectoral fin length. Genetic differences between the subspecies have been studied, and tend to indicate reproductive isolation occurred in the Pleistocene period. Behavioral differences are more clear, especially the dietary habits. Adult Gulf sturgeon eat primarily, or possibly only, during the winter, when they are in marine or brackish water, and eat little to nothing during the remainder of the year when they are in rivers. [ citation needed ] Their weights vary in accordance with this eating pattern, with significant weight gains in the winter and smaller weight losses in the summer. Because their diet consists of mollusks that can cause paralytic shellfish poisoning (PSP), in addition to other bottom-dwelling organisms such as grass shrimp, marine worms, isopods, and amphipods, their unique feeding pattern possibly reflects an adaptation to prevent PSP that coincides with higher rates of algal blooms in summer. [5] [7]
Juvenile Gulf sturgeon remain in the spawning river until roughly two years of age, eating there. Thereafter, they join the adults in their anadromous migrations and eating habits. The upriver migration normally occurs between February and April, as river temperatures rise to 16 to 23 °C (61 to 73 °F). Downriver migration normally begins in late September or October when water temperatures drop to 23 °C (73 °F). Males reach sexual maturity between seven and 12 years of age, females between eight and 17 years of age. Spawning almost always occurs in the natal river, generally over a hard bottom just downstream of a spring on the river bottom feeding groundwater into the river. After spawning, the adults and older juveniles collect in regions of cooler, deeper, slower-flowing water, generally downstream of springs. [5] [8] [7]
All species of sturgeon leap out of the water at times. The Gulf sturgeon tends to jump during July and August, and again early during the offshore feeding period. They are thought to jump to communicate and maintain group cohesion. [8] Due to their heavy body armor, large leaping sturgeon can inflict serious injuries to humans who are in the way. [9] On July 2, 2015, a leaping sturgeon on the Suwannee River in Florida struck and killed a 5-year-old girl. [10]
Predators of the sturgeon, other than humans, are unknown, but thought to have limited impact upon the species. Parasites include the fish louse Argulus stizostehi , nematodes, trematodes, and leeches. No detrimental impacts from these parasites have been observed. The species also serves as host to the glochidia (larvae) of three freshwater mussel species. Overfishing and dam construction probably contributed to the historical decline in populations. [7]
Sturgeon is the common name for the 28 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early Jurassic period, some 174 to 201 million years ago. They are one of two living families of the Acipenseriformes alongside paddlefish (Polyodontidae). The family is grouped into four genera: Acipenser, Huso, Scaphirhynchus, and Pseudoscaphirhynchus. Two species may be extinct in the wild, and one may be entirely extinct. Sturgeons are native to subtropical, temperate and sub-Arctic rivers, lakes and coastlines of Eurasia and North America. A Maastrichtian-age fossil found in Morocco shows that they also once lived in Africa.
The beluga, also known as the beluga sturgeon or great sturgeon, is a species of anadromous fish in the sturgeon family (Acipenseridae) of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and formerly in the Adriatic Sea. Based on maximum size, it is the third-most-massive living species of bony fish. Heavily fished for the female's valuable roe, known as beluga caviar, wild populations have been greatly reduced by overfishing and poaching, leading IUCN to classify the species as critically endangered.
The kaluga, also known as the river beluga, is a large predatory sturgeon found in the Amur River basin. With a maximum size of at least 1,000 kg (2,205 lb) and 5.6 m (18.6 ft), the kaluga is one of the biggest of the sturgeon family. Like the slightly larger beluga, it spends part of its life in salt water. Unlike the beluga, this fish has 5 major rows of dermal scutes and feeds on salmon and other fish in the Amur. They have gray-green to black backs with a yellowish green-white underbelly.
Acipenser is a genus of sturgeons. With 17 living species, it is the largest genus in the order Acipenseriformes. The genus is paraphyletic, containing all sturgeons that do not belong to Huso, Scaphirhynchus, or Pseudoscaphirhynchus, with many species more closely related to the other three genera than they are to other species of Acipenser. They are native to freshwater and estuarine systems of Eurasia and North America, and most species are threatened. Several species also known to enter near-shore marine environments in the Atlantic, Arctic and Pacific oceans.
The lake sturgeon, also known as the rock sturgeon, is a North American temperate freshwater fish, one of about 25 species of sturgeon. Like other sturgeons, this species is a bottom feeder and has a partly cartilaginous skeleton, an overall streamlined shape, and skin bearing rows of bony plates on the sides and back.
The Chinese sturgeon is a critically endangered member of the family Acipenseridae in the order Acipenseriformes. Historically, this anadromous fish was found in China, Japan, and the Korean Peninsula, but it has been extirpated from most regions due to habitat loss and overfishing.
The European sea sturgeon, also known as the Atlantic sturgeon or common sturgeon, is a species of sturgeon native to Europe. It was formerly abundant, being found in coastal habitats all over Europe. It is anadromous and breeds in rivers. It is currently a critically endangered species. Although the name Baltic sturgeon sometimes has been used, it has now been established that sturgeon of the Baltic region are A. oxyrinchus, a species otherwise restricted to the Atlantic coast of North America.
White sturgeon is a species of sturgeon in the family Acipenseridae of the order Acipenseriformes. They are an anadromous (migratory) fish species ranging in the Eastern Pacific; from the Gulf of Alaska to Monterey, California. However, some are landlocked in the Columbia River Drainage, Montana, and Lake Shasta in California, with reported sightings in northern Baja California, Mexico.
The Atlantic sturgeon is a member of the family Acipenseridae, and, along with other sturgeon, it is sometimes considered a living fossil. The Atlantic sturgeon is one of two subspecies of A. oxyrinchus, the other being the Gulf sturgeon. The main range of the Atlantic sturgeon is in eastern North America, extending from New Brunswick, Canada, to the eastern coast of Florida, United States. A disjunct population occurs in the Baltic region of Europe. The Atlantic sturgeon was in great abundance when the first European settlers came to North America, but has since declined due to overfishing, water pollution, and habitat impediments such as dams. It is considered threatened, endangered, and even locally extinct in many of its original habitats. The fish can reach 60 years of age, 15 ft (4.6 m) in length and over 800 lb (360 kg) in weight.
The shovelnose sturgeon is the smallest species of freshwater sturgeon native to North America. It is often called hackleback, sand sturgeon, or switchtail. Switchtail refers to the long filament found on the upper lobe of the caudal fin. Shovelnose sturgeon are the most abundant sturgeon found in the Missouri River and Mississippi River systems, and were formerly a commercially fished sturgeon in the United States of America. In 2010, they were listed as threatened under the U.S. Endangered Species Act due to their resemblance to the endangered pallid sturgeon, with which shovelnose sturgeon are sympatric.
The sterlet is a relatively small species of sturgeon from Eurasia native to large rivers that flow into the Black Sea, Azov Sea, and Caspian Sea, as well as rivers in Siberia as far east as Yenisei. Populations migrating between fresh and salt water (anadromous) have been extirpated.Also known as Sterlet sturgeon.
The starry sturgeon also known as stellate sturgeon or sevruga, is a species of sturgeon. It is native to the Black, Azov, Caspian and Aegean sea basins, but it has been extirpated from the last and it is predicted that the remaining natural population will follow soon due to overfishing.
The shortnose sturgeon is a small and endangered species of North American sturgeon. The earliest remains of the species are from the Late Cretaceous Period, over 70 million years ago. Shortnose sturgeons are long-lived and slow to sexually mature. Most sturgeons are anadromous bottom-feeders, which means they migrate upstream to spawn but spend most of their lives feeding in rivers, deltas and estuaries. The shortnose sturgeon is often mistaken as a juvenile Atlantic sturgeon because of its small size. Prior to 1973, U.S. commercial fishing records did not differentiate between the two species: both were reported as "common sturgeon", although it is believed based on sizes that the bulk of the catch was Atlantic sturgeon. The shortnose is distinguishable from the Atlantic sturgeon due to its shorter and rounder head.
The coastal cutthroat trout, also known as the sea-run cutthroat trout, blue-back trout or harvest trout, is one of the several subspecies of cutthroat trout found in Western North America. The coastal cutthroat trout occurs in four distinct forms. A semi-anadromous or sea-run form is the most well known. Freshwater forms occur in both large and small rivers and streams and lake environments. The native range of the coastal cutthroat trout extends south from the southern coastline of the Kenai Peninsula in Alaska to the Eel River in Northern California. Coastal cutthroat trout are resident in tributary streams and rivers of the Pacific basin and are rarely found more than 100 miles (160 km) from the ocean.
The green sturgeon is a species of sturgeon native to the northern Pacific Ocean, from China and Russia to Canada and the United States.
The Persian sturgeon is a species of fish in the family Acipenseridae. It is found in the Caspian Sea and to a lesser extent the Black Sea and ascends certain rivers to spawn, mainly the Volga, Kura, Araks and Ural Rivers. It is heavily fished for its flesh and its roe and is limited in its up-river migrations by damming of the rivers. Young fish feed on small invertebrates, graduating to larger prey such as crabs and fish as they grow. The threats faced by this fish include excessive fishing with the removal of immature fish before they have bred, damming of the rivers, loss of spawning areas and water pollution. The International Union for Conservation of Nature has listed the fish as critically endangered and has suggested that the increased provision of hatcheries could be of benefit.
The hickory shad, fall herring, mattowacca, freshwater taylor or bonejack is a member of the herring family Clupeidae, ranging along the East Coast of the United States from Florida to the Gulf of Maine. It is an anadromous fish species, meaning that it spawns in freshwater portions of rivers, but spends most of its life at sea. It is subject to fishing, both historic and current, but it is often confused with or simply grouped together with American shad in catch statistics.
The bastard sturgeon, also known as the fringebarbel sturgeon, ship sturgeon, spiny sturgeon, or thorn sturgeon, is a species of fish in the family Acipenseridae. These fish are typically found along the benthos of shallower waters near shorelines or estuaries.
Acipenser oxyrinchus is a species of sturgeon.
The Alabama shad is an anadromous species of clupeid fish endemic to the United States where it breeds in medium to large flowing rivers from the Mississippi River drainage to the Suwannee River, Florida, as well as some other Gulf coast drainages. The biology of this fish is little known but it has become increasingly rare. The International Union for Conservation of Nature rated it "near threatened" in 2020 and the United States National Marine Fisheries Service has listed it as a Species of Concern. A principal reason for its decline is thought to be the many locks and dams blocking access for the fish to up-river spawning grounds.