1 . Bony fish species and populations may become endangered or threatened due to overfishing, pollution, introduction of non-native species, and habitat destruction.
2. As of 1 993, more than 100 species of native bony fishes were considered endangered or threatened with extinction by the United States Fish and Wildlife Service (USFWS). Following are a few of the federally listed species:
a. Although the desert pupfish (Cyprinodon macularius) can withstand great environmental changes, the construction of irrigation and flood control dams has eliminated the marshy pools where desert pupfish breed. Due to low water levels, desert pupfish have been forced into mainstream channels where they are preyed upon by larger fishes.
b. The gila trout (Oncorhynchus gilae) is endangered due to degraded water quality, overfishing, and hybridization with non-native trouts. Non-native species of trout introduced for game fishing can breed with the gila trout to produce a hybrid trout. As gila trout continue to reproduce with other species of trout, their populations will decrease.
c. The shortnosed sturgeon (Acipenser brevirostrum) has been cut off from many of its natural spawning grounds along the Atlantic coast by dams. Pollution in major rivers and estuaries has also been a significant factor in the decline of this species.
d. Perhaps the biggest threats to chinook salmon (Oncorhynchus tshawytscha) populations are water management projects such as hydroelectric dams, which alter water flow, hinder migration, and negatively impact traditional spawning grounds. Poor water quality, overfishing, and inadequate regulations are additional factors contributing to the chinook salmon's demise.
3. Many other species of bony fishes are listed as endangered by individual U.S. states.
1 . Several federal agencies govern fishing laws and regulations, notably the National Marine Fisheries Service (NMFS), and the U.S. Fish and Wildlife Service (USFWS). Other federal agencies that have responsibility for fish management and conservation include the U.S. Forest Service, The Bureau of Land Management (BLM), and the National Park Service.
2. State agencies such as state Departments of Natural Resources (DNR), state Departments of Environmental Protection (DEP), and state Departments of Fish and Game may also enact fishing laws and regulations for the state.
3. Because some fishes (such as tunas and billfishes) migrate through waters under the jurisdiction of several nations, international cooperation is required for successful conservation.
1. An alternative to commercial fishing is aquaculture. Catfish farming is a huge industry in the U.S. Salmon, trout, sturgeon, and striped bass (Morone saxitilis) are other fishes farmed in the U.S.
2. In conjunction with the California Department of Fish and Game, the Hubbs- Sea World Research Institute (HSWRI) raises white seabass (Atractoscion nobilis) fingerlings and releases them in Southern California coastal waters.
a. HSWRI scientists are developing programs to improve culture technology, evaluate population characteristics, evaluate habitat requirements, assess stocking methods, and develop methods to monitor wild populations.
HSWRI scientists continue to develop programs to improve aquaculture technology.
b. To evaluate the hatchlings'success in the wild, researchers insert a coded wire tag into the cheek muscle of the fish. The tag allows researchers to identify individual release groups and helps them learn about the population as it develops.
1 - Anadromous fishes hatch in freshwater environments and must travel downriver to the sea to complete their life cycle. Without assistance, hydroelectric dams would make this migration impossible. Young fish headed toward the ocean can be barged downriver, sent over the dam, or guided to a bypass channel.
2. After spending several years at sea, anadromous fishes must travel upriver to spawn. A fish ladder next to a dam provides a way for these fish to travel upriver.
To conserve fishes and fisheries, scientists continue to study the abundance, reproduction rate and biology, migration, and catch information on various fish species.
Breeding programs for several endangered bony fish species are conducted by partici- pating American Zoo and Aquarium Association (AZA) institutions. Sea World of Ohio participates in an AZA program dedicated to saving the unique fish fauna of Lake Victoria in the African Rift Valley.
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