Instruct: Given a question, retrieve passages that answer the question.
Query: When did the pallid sturgeon become an endangered species?
Though never believed to be common, pallid sturgeon populations rapidly declined during the late 20th century and the species was listed as endangered on September 6, 1990. The U.S. government and most of the states with pallid sturgeon populations have commenced restoration efforts to save the species from extinction. Wild reproduction of pallid sturgeon is rare to nonexistent in most areas; therefore, human intervention is needed to ensure the survival of the species. Pallid sturgeon were previously considered a prized trophy game fish species, until their numbers declined and they were placed on the endangered species list. All captured pallid sturgeon must now be released back to the wild. The species was known for being very palatable and the roe from females was used as caviar.
The pallid sturgeon's snout and head are longer than that of the shovelnose sturgeon. In both species, the mouth is located well back from the tip of the snout. Lacking teeth, they use their extendable mouths to suck up small fish, mollusks, and other food sources from river bottoms. Both species also have four barbels which descend from the snout near the front of the mouth. The barbels are believed to be sensory features to locate food sources. On pallid sturgeon, the two inner barbels are about half as long as the outer ones, while on the shovelnose sturgeon, all four barbels are the same length. The inner barbels of the pallid sturgeon are positioned in front of the outer ones, but those on the shovelnose sturgeon are all located in essentially a straight line. The length and positioning of the barbels is one of the best ways to distinguish the two species.
Pallid sturgeon are generally bottom feeders, skimming the sandy reaches of the various rivers and streams in their habitat. Though little is known about the precise eating habits of the species, they are thought to be opportunistic feeders. One study which examined the contents from the stomachs of juvenile pallid sturgeon revealed that their diets were seasonally dependent. Various insects were consumed during some seasons and various fish species during others. These results support the description of the pallid sturgeon's eating habits as opportunistic. Fish is a more important dietary staple for pallid sturgeon than it is for shovelnose sturgeon. In one study comparing dietary tendencies between adult shovelnose sturgeon and immature pallid sturgeon, the pallid sturgeon was found to consume far greater numbers of small fish such as cyprinids (minnows). In another study conducted in the upper Missouri River region, an examination of the stomach contents of hatchery-reared pallid sturgeon showed that 82% of the wet weight was small fish and the balance was mosquito-like insects, mayflies, and caddis flies and small amounts of detritus and plant material.
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 50 meters. 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.
The Shasta Dam has had a severe negative effect on populations of Pacific salmon in the Sacramento River watershed ever since its gates were first closed in 1943. The massive structure completely prevents salmon migration from the lower reaches of the river to the Upper Sacramento, Pit, McCloud and other tributary streams. It is estimated that half of the best salmon habitat in the Sacramento basin lies upstream of Shasta Dam. Also, the dam caused temperatures in the river to rise because it released waters from higher elevations of Shasta Lake, which are warmed by the sun far more than the surface of the original river pre-dam. Warm waters are harmful to salmon, which prefer colder temperatures, and also impact other fish populations such as steelhead and wild California trout.
Swells dropped to 1–1.5 m on 28 June 2011, allowing more netting of sardines. Sardines were netted at Amanzimtoti; on the main beach and at Chain Rocks. A 22-year-old American marine biology student (research diver) named Paulo Edward Stanchi was attacked by a large dusky shark while diving at Aliwal Shoal Marine Protected Area. The group of divers had encountered a pocket of sardines when a 3 m long dusky shark bit Mr Stanchi on his left leg and hands. Mr Stanchi managed to free himself from the shark, and was treated on the diving boat before being transported to Rocky Bay, where medics stabilised him. He was then airlifted to Nkosi Albert Luthuli Hospital, where he underwent surgery. Dusky sharks generally live offshore, but come closer to the shore during the sardine run. The annual sardine run allowed more dusky sharks in the Aliwal Shoal MPA than usual, but there was no reason for them to show any more interest in divers than usual. Mr Stanchi had been wearing split fins with black and grey stripes, and this may have looked like a small shoal of fish to the shark. Meanwhile, a woman in her 40s broke her leg in the frenzy at Amanzimtoti when the sardines were netted. The woman is believed to have been trying to get some of the sardines when she "stepped wrong" and fractured her leg. Paramedics stabilized her before transporting her to hospital.
By the late 20th and early 21st centuries, the government blamed crashing fish populations on overfishing, especially off the Northern California and Oregon coast, which lie directly adjacent to the migration paths of Sacramento River salmon. This has resulted in a ban on coastal salmon fishing for several years since 2002. The Red Bluff Diversion Dam, although not a large dam and equipped with fish passage facilities, also presents a major barrier. Because of inadequate design, roughly 25–40% of the incoming fish get blocked by the dam each year. The dam has also become a "favorite spot" for predatory fish to congregate, feasting on the salmon that get trapped both above and below the dam. As of 2010, the salmon run has shown slight signs of improvement, probably because of that year's greater precipitation.
"M. gigas" was originally described by the Swedish naturalist Carl Peter Thunberg in 1795. It originated from Japan, where it has been cultured for hundreds of years. It is now the most widely farmed and commercially important oyster in the world, as it is very easy to grow, environmentally tolerant, and easily spread from one area to another. The most significant introductions were to the Pacific Coast of the United States in the 1920s and to France in 1966. In most places, the Pacific oyster was introduced to replace the native oyster stocks which were seriously dwindling due to overfishing or disease. In addition, this species was introduced to create an industry that was previously not available at all in that area. In addition to intentional introductions, the Pacific oyster has spread through accidental introductions either through larvae in ballast water or on the hulls of ships. In some places in the world, though, it is considered by biosecurity, primary industry, and conservation departments and ministries to be an invasive species, where it is outcompeting native species, such as the Olympia oyster in Puget Sound, Washington; the rock oyster, "Saccostrea commercialis", in the North Island of New Zealand; and the blue mussel, "Mytilus edulis", in the Wadden Sea.
Nearly 100 species of reptiles occur in the Eastern Ghats. Many endangered species are also present, including the mugger crocodile "(Crocodylus palustris)", Indian black turtle "(Melanochelys trijuga)", Indian flapshell turtle "(Lissemys punctata)", Indian tent turtle "(Pangshura tentoria)", Indian star tortoise "(Geochelone elegans)", Leith's softshell turtle "(Nilssonia leithii)", many of which are found in the northern rivers and riverine valley tracts.
Platecarpus ("flat wrist") is an extinct genus of aquatic lizards belonging to the mosasaur family, living around 84–81 million years ago during the middle Santonian to early Campanian, of the Late Cretaceous period. Fossils have been found in the United States and a possible specimen in Belgium and Africa. A well-preserved specimen of "Platecarpus" shows that it fed on moderate-sized fish, and it has been hypothesized to have fed on squid, and ammonites as well. Like other mosasaurs, it was initially thought to have swum in an eel-like fashion, although another study suggests that it swam more like modern sharks. An exceptionally well-preserved specimen of "P. tympaniticus" known as LACM 128319 shows skin impressions, pigments around the nostrils, bronchial tubes, and the presence of a high-profile tail fluke, showing that it and other mosasaurs did not necessarily have an eel-like swimming method, but were more powerful, fast swimmers. It is held in the Natural History Museum of Los Angeles County.
Pteranodon (; from Greek πτερόν ( pteron, "wing") and ἀνόδων (anodon, "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with wingspans over 8 meters (26 feet). They lived during the late Cretaceous geological period of North America in present-day Kansas, Alabama, Nebraska, Wyoming, and South Dakota. More fossil specimens of "Pteranodon" have been found than any other pterosaur, with about 1,200 specimens known to science, many of them well preserved with nearly complete skulls and articulated skeletons. It was an important part of the animal community in the Western Interior Seaway.
The diet of "Pteranodon" is known to have included fish; fossilized fish bones have been found in the stomach area of one "Pteranodon", and a fossilized fish bolus has been found between the jaws of another "Pteranodon", specimen AMNH 5098. Numerous other specimens also preserve fragments of fish scales and vertebrae near the torso, indicating that fish made up a majority of the diet of "Pteranodon" (though they may also have taken invertebrates).
Predators of the water rail include a number of mammals and large birds. The American mink was partly responsible for the extinction of the Icelandic population, and cats and dogs have also been recorded as killing this species. At least locally, otters will also eat rails and other water birds. The Eurasian bittern, another reed bed bird, will consume rails, as will grey herons. Water rails are particularly vulnerable to the heron when forced out of the cover of the reeds by very high tides. Wetland-hunting harriers are predictable predators, but more unusually, the rail has also been recorded as a prey item of the tawny owl, short-eared owl, Eurasian eagle-owl, greater spotted eagle, common kestrel, and night-hunting peregrine falcons.
Neogobius pallasi, the Caspian sand goby or the Caspian monkey goby, is a species of fish native to fresh and brackish waters of the Caspian Sea basin including the Volga drainage up to the vicinity of Moscow. It has been introduced into the Aral basin. This species of goby can reach a length of SL. It is also important to local commercial fisheries.
Some species of sea urchins, such as the slate pencil urchin ("Eucidaris tribuloides"), are commonly sold in aquarium stores. Some species are effective at controlling filamentous algae, and they make good additions to an invertebrate tank.
Michigan State University, Kellogg Biological Station: Eminent Ecologist (1992)
Cantor's giant softshell turtle or Asian giant softshell turtle ("Pelochelys cantorii") is a species of freshwater turtle native to Southeast Asia. It has been considered among the largest extant freshwater turtle. The species is endangered and in the 20th century has disappeared from much of its former range.
Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams (e.g., char and gudgeon) to the abyssal and even hadal depths of the deepest oceans (e.g., gulpers and anglerfish), although no species has yet been documented in the deepest 25% of the ocean. With 33,600 described species, fish exhibit greater species diversity than any other group of vertebrates.
There are many species of small birds, but most of the larger common Latin American types are absent. Few freshwater fish are native, but North American trout have been successfully introduced into the Andean lakes. Owing to the vicinity of the Humboldt Current, ocean waters abound with fish and other forms of marine life, which in turn support a rich variety of waterfowl, including several penguins. Whales are abundant, and some six species of seals are found in the area.
Five black bear populations, occurring in Kyushu, Shikoku, West-Chugoku, East-Chugoku and Kii areas, were listed as endangered by the Environmental Agency in the Japanese Red Data Book in 1991. Small isolated populations in the Tanzawa and Shimokita areas of mainland Honshū were listed as endangered in 1995. Beyond recognising these populations as endangered, there is still a lack of efficient conservation methods for Japanese black bears.
Stocks off the eastern United States are severely overfished; a 2006 stock assessment survey by the U.S. National Marine Fisheries Service (NMFS) showed that its population had dropped to 15–20% of 1970s levels. In 1997, the dusky shark was identified as a Species of Concern by the NMFS, meaning that it warranted conservation concern but there was insufficient information for listing on the U.S. Endangered Species Act (ESA). Commercial and recreational retention of dusky sharks was prohibited in 1998, but this has been of limited effectiveness due to high bycatch mortality on multi-species gear. In addition, some 2,000 dusky sharks were caught by recreational fishers in 2003 despite the ban. In 2005, North Carolina implemented a time/area closure to reduce the impact of recreational fishing. To aid conservation efforts, molecular techniques using polymerase chain reaction (PCR) have been developed that can identify whether marketed shark parts (e.g. fins) are from prohibited species like the dusky shark, versus similar allowed species such as the sandbar shark.
Scaphirhynchus is a genus of sturgeons native to the United States of America. All species in this genus are considered to be threatened. The pallid sturgeon is Endangered and the Alabama sturgeon is Critically Endangered.
To better protect the pallid sturgeon from extinction, research on its DNA and that of other closely related species was conducted to assess the differences within various populations of pallid sturgeon, and the differences between pallid and shovelnose sturgeon. Early DNA research indicated that pallid sturgeon and shovelnose sturgeon were a single species. However, a 2000 study comparing DNA sequences in the three members of the genus "Scaphirhynchus"(pallid, shovelnose, and Alabama sturgeon) showed that the three are distinct species. Between 2001 and 2006, several studies examined two populations of pallid sturgeon located in the upper Great Plains section of the Missouri River and compared them to a southern population located in the Atchafalaya River in Louisiana. These DNA studies concluded that the northern populations of pallid sturgeon are reproductively isolated and are genetically distinct from the Atchafalaya population. However, the genetic variability among pallid sturgeon was found to be far less than that between them and the shovelnose sturgeon.
The pallid sturgeon ("Scaphirhynchus albus") is an endangered species of ray-finned fish, endemic to the waters of the Missouri and lower Mississippi river basins of the United States.
The pallid sturgeon's historical range spanned the entire Missouri River and into the Mississippi River. Historically, the species was rare to nonexistent in the upper Mississippi, probably due to a lack of proper habitat. Currently, the species is considered imperiled throughout its entire range. As of 2008, pallid sturgeon can still be found throughout their original range, but their population numbers have severely declined from the mid-20th century. The Missouri and Mississippi rivers from Montana to Louisiana, as well as the Atchafalaya River in Louisiana, continue to harbor an aging population of pallid sturgeon. Pallid sturgeon have never been very common; as early as 1905 when the species was first identified, they represented only one in five of all sturgeon in the lower Missouri River and as few as one in 500 where the Illinois River meets the Mississippi. Between 1985 and 2000, the ratio of pallid sturgeon to all sturgeon netted declined from one in about 400 to one in nearly 650. A 1996 study concluded that between 6,000 and 21,000 pallid sturgeon remained in their natural habitat at that time.