| Acipenser oxyrinchus | |
|---|---|
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| A. o. oxyrinchus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Acipenseriformes |
| Family: | Acipenseridae |
| Genus: | Acipenser |
| Species: | A. oxyrinchus |
| Binomial name | |
| Acipenser oxyrinchus Mitchill 1815 | |
| Subspecies | |
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| Synonyms [3] [4] | |
| |
Acipenser oxyrinchus is a species of sturgeon.
Acipenser oxyrinchus is a species with two subspecies:
Their main diet includes crustaceans, worms, and molluscs. This species is also known to migrate up the river when it is spawning. [5] This species is recorded to be near threatened and at risk of becoming an endangered species due to dam construction, dredging, dredge spoil disposal, groundwater extraction, irrigation, flow alterations, and other surface water withdrawals. Acipenser oxyrinchus is mostly native to the countries of Canada and the United States, with a smaller population in northern Europe (essentially the Baltic region). [3] This population is considered Critically Endangered by the IUCN. [6] They can be found in temperate and subtropical climates and in marine or freshwater environments. [3]
Acipenser oxyrinchus can grow to a length of 14 ft (4.3 m) and a weight of 800 lb (360 kg). The lifespan of this species can be around 60 years. The color of Acipenser oxyrinchus is bluish-black or olive brown with lighter sides and a white belly.
Sturgeon are an anadromous species that live solitarily or in small groups. They migrate upriver in the spring to spawn. Sturgeons tend to inhabit the shallow waters of coastal shelves, coastal and estuarine areas on soft bottom in the sea, and can live down to a depth of 160 ft (49 m). Adults are migratory while at sea and will make long migrations to coastal areas, while juveniles will stay in fresh or brackish water until they are between two and five years of age. However, many larvae and juveniles do start to migrate and disperse small distances from their spawning sites. [3]
Sturgeons will migrate upriver to spawn. Sturgeons from the Gulf of Mexico will naturally exhibit spawning migration in the spring. Peak numbers have been observed in March and April, which is when the fish will migrate into the Suwannee River in Florida. [7] Sturgeon will migrate downstream for twelve days, peaking within the first six days. Atlantic sturgeons only need to move a short distance to reach rearing areas. Early sturgeon migrants tend to be nocturnal while later migrants are diurnal. [8] During summer months, sturgeon will remain in localized bottom areas of the rivers. In the late fall, the sturgeon migrate out of spawning rivers and into the Gulf of Mexico. [7]
For all populations and subspecies of sturgeon, there are spawning migrations into freshwater in early spring and movement into salt water in the fall. Timing and the unusual migratory behavior of sturgeon is a result of temporal water temperature changes. [7] Studies have also shown that amongst sturgeon in Gulf of Mexico and Suwannee River in Florida, fish gained 20% of their body weight while in Gulf of Mexico and lost 12% of their body weight during their time in the river. [9]
The maximum level of survival for eggs, embryos, and larvae is at 15 to 20 °C (59 to 68 °F). Studies have shown that high mortalities are seen at temperatures of 25 °C (77 °F) or higher. [7] In order for spawning to occur, water temperature should be above 17 °C (63 °F). Spawning normally lasts between nine and twenty-three days, but can continue past this as long as the water temperature remains below 22 °C (72 °F). [10]
Free sturgeon embryos (the first interval of sturgeon after hatching) hide under rocks and do not migrate. They are found in the freshwater spawning areas. Larvae and some juveniles start to migrate slowly for about five months downstream. This leads to a wide dispersal of the fish. [11] Typically, the entire freshwater reach of the river downstream from the actual spawning site is so filled with larva-juvenile individuals that it is considered to be a nursery habitat. [11]
Sturgeon populations will use the same spawning reefs from year to year. Habitat factors that can help determine spawning sites include the presence of gravel substrate, presence of eddy fields, slightly basic pH, and a range in calcium ion content. Eggs are usually deposited in a small area and scatter very little. It is not until larvae and juveniles start to migrate that the fish disperse widely. [10]
Some evidence has shown that developmental body color is related to migration style. Free embryos are light and are non-migratory, while migratory larvae and adults are dark. This is found to be consistent among many Acipenser species. The reason for this is unclear, but it may be adaptive to migration behavior and camouflage. [11]
The primary foods of sturgeon while in freshwater areas include soft-bodied annelids, arthropods, aquatic insects, and globular mollusks. Adults that have emigrated from estuaries and into the sea will usually feed on epibenthic and hyperbenthic amphipods, grass shrimp, isopods, and worms. Most adult sturgeon will also feed on detritus and biofilm. [12] Sturgeons are most generally known for feeding on crustaceans, worms, and molluscs. [13]
Larvae-juvenile feeding was at the bottom, benthic foraging. However, food in the benthic zone is scarce, so many adapt drift feeding, in which they have holding positions in the water column and wait for food. [11] Sturgeons may have dominance hierarchies with large fish being dominant when competing for limited foraging space. [8]
Sturgeons are widely distributed along the Atlantic coast of the United States. Their wide distribution and tendency to disperse has led to numerous subpopulations of sturgeon. [13]
In general, sturgeons usually inhabit primarily the temperate waters of the northern hemisphere. Gulf of Mexico sturgeons are probably adapted to warmer water temperatures. Due to sturgeons' predilection for cooler waters, when water temperatures rise too high, sturgeon will try to find cool spring waters which serve as thermal refuges until temperatures drop again. [7]
There are many wide-ranging subspecies along the Atlantic Coast of North America. Identification of distinct population segments (DPS) is problematic because of sturgeons' ability to disperse so widely. However, it is possible to do some characterization of genetic differentiation and estimate gene flow. This method has been used to determine possibility for listing under the U.S. Endangered Species Act. [14]
The sturgeon's characteristics and life history make it susceptible to anthropogenic disturbances and make population restoration particularly difficult. They have late sexual maturity, only moderate fecundity, and spawn at low frequencies. Females spawn once every three to five years, and males every one to five years. This is due to their ability to live for an extremely long time (various sub-species can have a lifespan ranging from ten years to sixty years). [14]
The population of Atlantic sturgeons has decreased dramatically due to overharvesting. The late 19th century saw a surge in demand for caviar, which led to overfishing of the Atlantic sturgeon. Today, only 22 out of its 38 original spawning rivers still have viable populations of the species. [15] They are particularly susceptible to bycatch mortality due to the many fisheries that exist within their natal estuaries. Their habitat range, which usually includes coastal spawning sites and coastal migrations, makes sturgeon well within contact of coastal fisheries. [14]
Hypoxia combined with high water temperatures in the summer has been shown to be consistent with decreased survival rates of young of the year sturgeon in Chesapeake Bay. [16]
Hypoxia is defined as low ambient oxygen levels, which may be very harmful to organisms living in the hypoxic body of water. Often, lower regions of the water column will be more hypoxic than upper levels, closer to the surface. When surface access is denied, the situation is lethal to sturgeon. Increased incidences of summertime hypoxia have led, in part, to degradation of many sturgeon nursery habitats in the United States. [16]
Populations have declined dramatically over the last centuries, and even became extinct in Baltic range states in the later 20th century. Channelisation and barriers were part of the causes for declines affecting migration, along with pollution. Since 1996 Baltic sturgeon recovery has been attempted, with American donor populations used due to genetic similarities. Re-introduction with focus on returning these sturgeon to their native spawning grounds. [17] NatureServe considers the species Vulnerable. [18]
In 2012, the Atlantic sturgeon received protection under the Endangered Species Act. [19]
In 2022, the International Union for the Conservation of Nature noted that sturgeon was "the animal group most at risk of extinction in the world." [15]
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear.
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 American eel is a facultative catadromous fish found on the eastern coast of North America. Freshwater eels are fish belonging to the elopomorph superorder, a group of phylogenetically ancient teleosts. The American eel has a slender, supple, snake-like body that is covered with a mucus layer, which makes the eel appear to be naked and slimy despite the presence of minute scales. A long dorsal fin runs from the middle of the back and is continuous with a similar ventral fin. Pelvic fins are absent, and relatively small pectoral fins can be found near the midline, followed by the head and gill covers. Variations exist in coloration, from olive green, brown shading to greenish-yellow and light gray or white on the belly. Eels from clear water are often lighter than those from dark, tannic acid streams.
Eels are any of several long, thin, bony fishes of the order Anguilliformes. They have a catadromous life cycle, that is: at different stages of development migrating between inland waterways and the deep ocean. Because fishermen never caught anything they recognized as young eels, the life cycle of the eel was a mystery for a very long period of scientific history that continues into the present day. Of significant interest is the search for the spawning grounds for the various species of eels and identifying impacts to population decline in each stage of the life cycle.
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.
The common galaxias or inanga is a very widespread Southern Hemisphere fish in the family Galaxiidae. It is a slim, narrow fish with a forked tail and a mottled, spotty pattern, typically about 10 cm (4 in) long when fully grown. It lives in fresh water, but spawns at river mouths and spends the first six months of its life at sea, returning en masse in spring. Its vernacular names include cowfish, jollytail, common jollytail, eel gudgeon, inaka, native trout, pulangi, puye, slippery tarki, spotted minnow, Falklands minnow and whitebait.
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 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 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 green sturgeon is a species of sturgeon native to the northern Pacific Ocean, from China and Russia to Canada and the United States.
The Gulf sturgeon 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. The Gulf sturgeon is listed as threatened under the United States Endangered Species Act, having been listed in 1991. Critical habitat, reflecting the range of the subspecies deemed essential for its continued survival, has been designated. 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.
The Adriatic sturgeon is a species of fish in the family Acipenseridae. It is native to the Adriatic Sea and large rivers which flow in it of Albania, Greece, Italy, Montenegro, Croatia, Bosnia and Herzegovina and Slovenia. Specimens can be seen in several public aquarium, such the Milan Aquarium, Aquarium Finisterrae, Aquarium of the Po, and Oasis of Sant'Alessio in Lombardy.
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.
The houting is a European species of whitefish in the family Salmonidae that was long thought extinct. It was native to the estuaries and rivers draining to the North Sea. The houting is distinguishable from other Coregonus taxa by having a long, pointed snout, an inferior mouth and a different number of gill rakers. The houting once occurred in Belgium, France, Germany, the Netherlands and England. In 2023, DNA analysis found the houting to be genetically indistinguishable from Coregonus lavaretus, and therefore not extinct.
The European flounder is a flatfish of European coastal waters from the White Sea in the north to the Mediterranean and the Black Sea in the south. It has been introduced into the United States and Canada accidentally through transport in ballast water. It is caught and used for human consumption.
Tarpon are fish of the genus Megalops. They are the only members of the family Megalopidae. Of the two species, one is native to the Atlantic, and the other to the Indo-Pacific Oceans.
Media related to Acipenser oxyrinchus at Wikimedia Commons
Data related to Acipenser oxyrinchus at Wikispecies