Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha and are the sister group to the Batoidea. Some sources extend the term "shark" as an informal category including extinct members of Chondrichthyes with a shark-like morphology, such as hybodonts. Shark-like chondrichthyans such as Cladoselache and Doliodus first appeared in the Devonian Period, though some fossilized chondrichthyan-like scales are as old as the Late Ordovician. The oldest modern sharks (selachians) are known from the Early Jurassic, about 200 Ma.
The great white shark, also known as the white shark, white pointer, or simply great white, is a species of large mackerel shark which can be found in the coastal surface waters of all the major oceans. It is the only known surviving species of its genus Carcharodon. The great white shark is notable for its size, with the largest preserved female specimen measuring 5.83 m (19.1 ft) in length and around 2,000 kg (4,410 lb) in weight at maturity. However, most are smaller; males measure 3.4 to 4.0 m, and females measure 4.6 to 4.9 m on average. According to a 2014 study, the lifespan of great white sharks is estimated to be as long as 70 years or more, well above previous estimates, making it one of the longest lived cartilaginous fishes currently known. According to the same study, male great white sharks take 26 years to reach sexual maturity, while the females take 33 years to be ready to produce offspring. Great white sharks can swim at speeds of 25 km/h (16 mph) for short bursts and to depths of 1,200 m (3,900 ft).
Bushmeat is meat from wildlife species that are hunted for human consumption. Bushmeat represents a primary source of animal protein and a cash-earning commodity for inhabitants of humid tropical forest regions in Africa, Latin America and Asia. Bushmeat is an important food resource in poor, rural communities.
The leafy seadragon or Glauert's seadragon, is a marine fish. It is the only member of the genus Phycodurus in the family Syngnathidae, which includes seadragons, pipefish, and seahorses.
Environmental issues in Australia describes a number of environmental issues which affect the environment of Australia. There are a range of such issues, some of the relating to conservation in Australia while others, for example the deteriorating state of Murray-Darling Basin, have a direct and serious effect on human land use and the economy.
The gummy shark, also known as the Australian smooth hound, flake, sweet william or smooth dog-shark, is a shark in the family Triakidae. These small to medium-sized bottom-dwelling sharks are found mostly in, but are not limited to, the area around the southern seas of Australia and is commonly baited and fished for cuisine because of its taste and market prices. According to a 2021 paper by White, Arunrugstichai & Naylorn (2021), Mustelus walkeri is the same animal as M. antarcticus. One theory is that M. walkeri is a subpopulation of M. antarcticus.
Chelydra is one of the two extant genera of the snapping turtle family, Chelydridae, the other being Macrochelys, the much larger alligator snapping turtle. The snapping turtles are native to the Americas, with Chelydra having three species, one in North America and two in Central America, one of which is also found in northwestern South America.
Hippocampus angustus, commonly known as the narrow-bellied seahorse, western Australian seahorse, or western spiny seahorse, is a species of marine fish of the family Syngnathidae. It is found in waters off of Australia, from Perth to Hervey Bay, and the southern portion of Papua New Guinea in the Torres Strait. It lives over soft-bottom substrates, adjacent to coral reefs, and on soft corals at depths of 3–63 metres (9.8–206.7 ft). It is expected to feed on small crustaceans, similar to other seahorses. This species is ovoviviparous, with males carrying eggs in a brood pouch before giving birth to live young. This type of seahorse is monogamous in its mating patterns. The males only fertilize one female's eggs for the mating season because of the population distribution. While some seahorses can be polygamous because they are denser in population, this type of seahorse is more sparsely distributed and the cost of reproduction is high. Therefore, the risk to reproduce due to predatory and distributary factors limits this breed to one mate, often finding the same mate season after season.
Barbour's seahorse is a species of fish of the family Syngnathidae.
Hippocampus whitei, commonly known as White's seahorse, New Holland seahorse, or Sydney seahorse, is a species of marine fish of the family Syngnathidae. It is thought to be endemic to the Southwest Pacific, from Sydney, New South Wales and southern Queensland (Australia) to the Solomon Islands. It lives in shallow, inshore habitats, both natural and anthropogenic. This species is ovoviviparous, with males brooding eggs in a brood pouch before giving birth to live young.
A drum line is an unmanned aquatic trap used to lure and capture large sharks using baited hooks. They are typically deployed near popular swimming beaches with the intention of reducing the number of sharks in the vicinity and therefore the probability of shark attack. Drum lines are often used in association with shark nets, which results in shark mortality. However SMART drum lines can be used to move sharks, which greatly reduces shark and bycatch mortality. The use of drum lines has been successful in reducing shark attacks in the areas where they are installed. The topic of shark culling became an international controversy and sparked public demonstrations and vocal opposition, particularly from environmentalists, animal welfare advocates and ocean activists.
The spiny seahorse, also referred to as the thorny seahorse, is a small marine fish in the family Syngnathidae, native to the Indo-Pacific area. It is classified as a Vulnerable species by the IUCN.
Amanda Vincent is a Canadian marine biologist and conservationist, one of the world's leading experts on seahorses and their relatives. She currently holds the chair of the IUCN SSC Seahorse, Pipefish and Seadragon Specialist Group and is the marine representative on the IUCN's International Red List Committee as well as being the chair of its Marine Conservation Committee. She previously held the Canada Research Chair in Marine Conservation at the UBC Institute for the Oceans and Fisheries at the University of British Columbia (UBC), Canada from 2002 to 2012. Vincent co-founded and directs Project Seahorse, an interdisciplinary and international organization committed to conservation and sustainable use of the world's coastal marine ecosystems. In 2020 she became the first marine conservationist to win the world's leading prize for animal conservation, the Indianapolis Prize.
The Simanjiro Conservation Easement is a novel payment for ecosystem services scheme in the Simanjiro Plains of Tanzania, an important wet-season grazing area between Tarangire National Park and Mount Kilimanjaro. This contractual agreement between individual villages and a consortium of tourism vendors obligates local residents to forgo agricultural activities in some areas in return for annual cash payments of 5 million Tanzanian shillings per village.
The Western Australian shark cull is the common term for a former state government policy of capturing and killing large sharks in the vicinity of swimming beaches by use of baited drum lines. The policy was implemented in 2014 to protect human swimmers from shark attack following the deaths of seven people on the Western Australian coastline in the years 2010 to 2013. National public demonstrations opposing the policy attracted international attention to the issue. In September 2014 the seasonal setting of drum lines was abandoned following a recommendation made by the Western Australian Environment Protection Authority. From December 2014 to March 2017, the special deployment of drum lines was permitted in cases where sharks were deemed to present a serious threat to public safety. This policy allowed the government of Western Australia to kill "high-hazard" sharks it found to be a threat to humans; the policy was criticized by senator Rachel Siewart for damaging the environment. In March 2017 the use of drum lines was abandoned by the newly elected West Australian state government. In August 2018 following continual shark attacks the West Australian state government reversed their position and announced a 12-month trial of "SMART" drumlines along Western Australia's South West coast, near Gracetown.
Pregnancy has been traditionally defined as the period of time eggs are incubated in the body after the egg-sperm union. Although the term often refers to placental mammals, it has also been used in the titles of many international, peer-reviewed, scientific articles on fish, e.g. Consistent with this definition, there are several modes of reproduction in fish, providing different amounts of parental care. In ovoviviparity, there is internal fertilization and the young are born live but there is no placental connection or significant trophic (feeding) interaction; the mother's body maintains gas exchange but the unborn young are nourished by egg yolk. There are two types of viviparity in fish. In histotrophic viviparity, the zygotes develop in the female's oviducts, but she provides no direct nutrition; the embryos survive by eating her eggs or their unborn siblings. In hemotrophic viviparity, the zygotes are retained within the female and are provided with nutrients by her, often through some form of placenta.
Shark culling is the deliberate killing of sharks by government authorities, usually in response to one or more shark attacks. The term "shark control" is often used by governments when referring to culls. Shark culling has been criticized by environmentalists, conservationists and animal welfare advocates—they say killing sharks harms the marine ecosystem and is unethical. Government officials often cite public safety as a reason for culling. The impact of culling is also minor compared to bycatch with 50 million sharks caught each year by the commercial fishing industry.
Adina Merenlender is a Professor of Cooperative Extension in Conservation Science at University of California, Berkeley in the Environmental Science, Policy, and Management Department, and is an internationally recognized conservation biologist known for land-use planning, watershed science, landscape connectivity, and naturalist and stewardship training.
The blonde ray or blonde skate is a species of ray fish in the family Rajidae.
Stacy Philpott is an American ecologist who is a professor at the University of California, Santa Cruz. Her research considers agroecology and the conservation of biodiversity. She was elected a Fellow of the Ecological Society of America in 2021.
