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Home , Diversity of fish, Freshwater fish, Game fish, Milt, Minnow, Pipefish

publication 420-525 Sustaining America’s Aquatic Biodiversity Freshwater Biodiversity and Conservation Louis A. Helfrich, Department of and Wildlife Sciences, Tech Richard J. Neves, Department of Fisheries and Wildlife Sciences, Virginia Tech

early 800 native fish in 36 families Unfortunately, nongame have declined sharply inhabit the freshwater , streams, and in abundance and diversity in the last 20 years. Twen- of the United States and Canada. North ty-seven species of fishes have become extinct during AmericaN has the most diverse temperate freshwater the past century. At least 16 species of fish have be- fish fauna in the world. Only about 5 percent of these come extinct in the United States since 1964. Nearly are the familiar sport or fishes like and all of the fishes in the Colorado are endangered . The remaining 95 percent are little known, but or threatened. Of the 490 Southeastern freshwater colorful, nongame (not sport fish) fishes such as dart- fishes, 91 are in trouble. At present, nearly 20 percent ers, , shiners, and dace. of the native freshwater fishes in are imperiled, meaning that they are endangered, threat- About one-third of North American fishes are in the ened, or of special concern. family (), and about one-fifth are in the darter and family (Percidae). The East- What Is a Fish? ern United States has nearly four times as many fish species as the western states, yet the Southwestern Fish are cold-blooded with a backbone (ver- deserts have a remarkable fish fauna. The Southeast- tebrates), for breathing underwater, and paired ern United States harbors the greatest diversity of for swimming. They live underwater and are fish, with over 600 native fishes. States with the rich- dependent on water for dissolved oxygen, support, est include Tennessee (307 species), food, and shelter. Marine (whales, dol- Kentucky (242 species), and Virginia (217 species). phins, seals, sea otters), (turtles), ( and ), (, clams, and Nongame fishes, although not pursued by anglers, are ), and aquatic (crayfish, , nevertheless important. They serve us in many ways ) are not fish. Although they may not look like and deserve our protection. Nongame fishes are an fish, and actually are fish. important ecological link in the , feeding on and serving as prey for sport fishes, , The three main groups of fish are and other wildlife. They also are important indicators • jawless fish (lampreys), of water quality and ecosystem health. For example, a • cartilaginous fishes ( and rays), and or the disappearance of fishes from a stream • bony fishes (most fish species). can alert citizens to water pollution.

www.ext.vt.edu Produced by Communications and Marketing, College of Agriculture and Life Sciences, Virginia Polytechnic Institute and State University, 2009 Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, national origin, , religion, age, disability, political beliefs, sexual orientation, or marital or family status. An equal opportunity/affirmative action employer. Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Rick D. Rudd, Interim Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Alma C. Hobbs, Administrator, 1890 Extension Program, Virginia State, Petersburg. The first two groups are primitive, ancient fishes, where- How do fishes breathe? All animals need oxygen to as the bony fishes are more recent, advanced fishes. survive. Land animals breathe atmospheric air that contains 21 percent oxygen. However, oxygen is not Fish exhibit the greatest biodiversity of the always available in water. Dissolved oxygen levels in (animals with backbones) with over 22,000 species. water can range from 0 percent to over 100 percent Of these, about 58 percent are marine, 41 percent are saturation, depending on water temperature, eleva- freshwater species, and 1 percent move back and forth tion, air pressure, other dissolved gases, and water between salt- and freshwater. As expected, marine quality. fishes are the most diverse because saltwater covers 70 percent of the earth. Only 1 percent of the earth is Fish extract dissolved oxygen from the water using covered by freshwater. their gills. In breathing, This small area is home to Dorsal fish first gulp a mouthful 8,000 species of freshwater of water, then close their fishes. Gil Plate Adipose Fin , and pressurize Eye Caudal Fin the water, forcing it over

Anglers prefer sport fish Jaws the rich red blood supply (trout, bass, and pike) of gills and out the oper- for their fighting or food cula (-flaps). Oxygen value. In contrast, non- is absorbed directly into Anal Fin are not com- Barbels Throat the fish’s blood supply monly sought by anglers Pectoral Fin and distributed through- because they are small fish out the body via the (minnows, darters, and Figure 1. External featues of a Composite fish . dace) or not particularly good eating (, , bullheads, , and Some fishes have an internal, inflatable air (swim) ). Ninety-five percent of fish are nongame fish. For bladder that evolved as an outgrowth of the intestine. example, of the 217 species of fish found in Virginia, The air bladder can be inflated or deflated to regulate only 25 are considered game fish. buoyancy and depth. Some fish use their air bladders to amplify underwater sound, and thereby increase their The science and study of fish is called ability to hear. Gar and use their air blad- (from the Greek word for fish, ichthyes). Fish have ders to gulp and breathe atmospheric oxygen. They can been raised and studied for centuries, beginning with survive in low-oxygen water for long periods. the early Chinese, Egyptians, and Greeks. The farming of fish and other aquatic animals is called . Nearly all fish have a protective slimy mucus cover- ing their skin. This outer coating reduces friction and Structure and appearance increases swimming speed. It also protects fish from parasites and diseases, and permits salt balance (os- Fish exhibit a variety of body forms. Some are moregulation). Removing the mucus layer by netting streamlined, torpedo-shaped (trout, sharks, and sail- and handling fish can increase their susceptibility to fish), allowing them to slip easily through the water. disease and disrupt their salt balance. Others are flattened top to bottom ( and rays) for living on the bottom and making surprise attacks Many fish are armored with transparent plates called on prey. Some fish are flattened laterally (sunfishes) scales that overlap like roof shingles. Some fish have so they can make quick turns. Long, thin, needle- no scales. Others have scales that reflect silvery shaped fish (gar and pike) are designed for high to confuse predators. Scales are used to identify fish forward speed to catch prey. and angelfish species and to age fish. By counting the number of mimic the leaves of waterweeds for camouflage. scales along the lateral line (mid-body hearing ), Fish vary in size more than any other group of ver- ichthyologists can accurately identify each fish spe- tebrates. The world’s biggest fish is the whale cies. Under the microscope, growth rings on scales which reaches 50 feet in length and weighs over 20 can be counted like tree rings to determine the age of tons. The smallest fish is the pygmy goby, which a fish. reaches only 0.3 inch in length.

2 Fish use their fins to stop, start, steer, turn, swim , American eels, and a few other fish can backward and forward, chase and catch food, and migrate between fresh- and saltwater. Salmon are migrate. The large, powerful (caudal) fin is impor- anadromous fish that are born in freshwater, migrate tant for forward speed. All fins, including the dorsal to and live in the , and then return to freshwater (top), pectoral (chest), and pelvic (abdominal) fins, (often their birth stream) to reproduce () and are used in swimming and maneuvering. The dorsal, die. Eels are catadromous fish. They are born in the caudal, and anal fins are median, unpaired fins. The ocean and migrate to freshwater to live, only return- pelvic and pectoral fins are paired. ing to the ocean to spawn.

Fin shape and location are important for swimming The rich diversity of fish (25,000 species) is due to and maneuvering. Fast swimming fish ( and the diversity of aquatic habitats and the range of wa- ) have long pointed and crescent-shaped fins ter quality in which they can live. It also results from that fold into body slots to reduce drag. immense isolation in time and space (fish evolved have long, broad wing-shaped fins that allow them to over millions of years in worldwide). jump and glide long distances above the surface. Puffer and box fish have small, rapidly-beat- Fish diversity is greater in streams than in lakes. ing fins for fine maneuvering. Frequently two to ten species of fish can be found in small streams, 15 to 30 species in an intermediate- Fins contain supporting sized stream, and 20 fin rays that can be soft, to 40 fish species in a hard, or a combination of river. An exceptional both. Hard, sharp fins can diversity of fishes is deliver a painful (even found in the South- toxic) jab when erected eastern United States, (some ). Pectoral where as many as 90 fins can be large and species of fish may live broad as in flying fishes in a single river. for gliding, or pointed as in fast swimmers like tuna, or rigid, diving planes as in sharks. Fast swimming, What do they eat? often have long, large dorsal fins. Fish diets consist of aquatic insects, , plants, and other fish. The structure and its Where do they live? location provide clues to what and where fish eat. Fish can be found in aquatic environments every- Predator fish (pike and pickerel) have large, sharp where. They live in high, cold mountain-top lakes; teeth and a long pointed snout on the front of the head deep, dark ocean depths; warm, tropical swamps; salt for grasping prey. Shellcracker sunfish have strong marshes; freezing Antarctic waters; shallow Arctic blunted teeth for crushing snails, mussels, and cray- streams; hot desert springs; salty coastal bays; large fish. A sucker’s mouth is located on the bottom of the muddy rivers; and crystal clear cold springs. head in order to vacuum up bottom-dwelling worms Salt balance (osmoregulation) is very important in the and insects. Topminnows have an upper-facing mouth internal chemistry () of both freshwater for sucking prey from the water surface. Surface- and marine fishes. Marine fish drink lots of saltwa- feeding fish (trout) eat drowning flies and insects ter and produce a very concentrated (salty) urine in floating or flying near the surface. Some fish, like the order to flush out excess salt. In contrast, freshwater stoneroller, use their horny lips to scrape algae from fish drink lots of freshwater, and produces a dilute rocks on the river bottom. (unsalty) urine in order to conserve essential salts. Because of these two very different salt-balance Most fish grow continuously throughout their lives, systems, most fish live exclusively in either fresh- or but growth slows with age. Fast growth is an indicator saltwater. However, a few fish have a wide salt toler- of healthy fish and abundant food. Some fish (stur- ance and can move between salty and freshwater. geon) can live for 50 years or more, whereas others may live less than one year.

3 How do they reproduce? Wild and farmed fish are an important source of hu- man food. Commercial for wild fish and the In most fish, spawning ( laying) and egg fertiliza- aquaculture of farmed fish are important industries tion are external, completed in the water. Male and worldwide. female fish simultaneously release () and () into the water where fertilization occurs. Fish is an ideal human food. It is nutritious; high in Some species scatter millions of eggs in the water protein, minerals, vitamins, and beneficial omega oils; where they are left unattended, whereas others lay and low in fat and cholesterol. The demand for only a few eggs and provide close . Male and fresh fish is increasing as more people are realiz- sunfish and catfish, for example, aggressively defend ing the health and fitness value of eating fish. Even fish their nest and young from predators and intruders. eggs ( from , , and shad) are luxury foods that command premium prices. Fish lay their eggs in many places, including in elaborate floating bubble nests, in bank hollows, and in clean bottom gravel. Fish Watching Others build spawn- Like watching, ing mounds of gravel observing fishes in clear or attach sticky eggs to water streams and lakes, aquatic plants, while oth- on reefs, and in ers lay eggs in underwa- aquaria are satisfying ter caves and cavities. hobbies. In the field, you can walk along the Some fish are live-bear- shoreline looking down into a stream or . Swim- ers. is internal and develop ming and with fish also is a good way within the female fish. The young are born fully to observe them. Underwater, humans appear less formed. threatening to fishes, which often are curious and closely approach underwater observers. Addition- ally, keeping a home fish is a great hobby What Good Are Fish? enjoyed by millions of people. Sport fishing is a popular recreational activity pursued by millions of adults and children. About 30 percent Threats of the people in the United States are recreational Many factors contribute to the loss of fish species and anglers. Some spend considerable money and time the degradation of their habitat. These include: trying to catch fish. Many of these anglers practice • and impoundments; fishing to assure good fishing for • water pollution, especially spills of toxic wastes future generations. (i.e., oil and petroleum products, industrial acids, pesticides, and fertilizers); Fish are an important ecological link in the food • sedimentation from agriculture, construction, and chain. They serve as food for other fish, herons, logging and mining; eagles, ospreys, alligators, turtles, otters, minks, rac- • introduction of exotic species; and coons, bears, other wildlife, and humans. • .

They also are important indicators of water qual- Dams block fish spawning migrations and isolate fish ity and ecosystem health. For example, a fish kill or from upstream spawning and nursery areas, causing the disappearance of fishes from a stream can alert populations of anadromous and catadromous fish to citizens to water pollution. Because of habitat loss, decline. As streams and rivers are transformed into , water pollution, dams, mining, and human lakes and reservoirs, alterations in downstream water development, fish diversity has been reduced. Fish, as flows and water temperatures, negatively impact do all aquatic life forms, serve as “sentinel” species, fish communities. River fish that have evolved and alerting people that water quality is changing. adapted to inhabit free-flowing rivers may not survive in lakes and reservoirs.

4 Water pollution threatens fish. Heated water (ther- Organize a local “river watchers” group to keep an mal discharge), low dissolved-oxygen levels, toxic eye on your streams and conduct stream improvement chemicals (gasoline and oil), and coal-mine acids projects. impact water quality and fish. Fish may temporarily avoid water pollution by swimming into small, clean Get involved in programs that restore coastal and tributary streams. However, they cannot live continu- streamside areas. Planting native trees and shrubs ously in a polluted stream. along riverbanks protects water quality and improves wildlife habitat. Exotic, introduced fish (i.e. ) also stress native Catch-and-release fishing species. They compete with allows anglers the enjoy- natives for habitat, spawning ment of catching fish sites, and food. Exotic fish like the snakehead are ag- and, then, freeing them to be caught another time by gressive predators that eat native fish. Aquarium pets another angler. Use barbless hooks, wet your hands should never be released into the wild where they can when handling fish, keep fish in the water, and avoid threaten native aquatic animals. touching the gills. Cut the line if the fish is hooked Conservation efforts and recovery projects by state deeply (stomach acids will dissolve the hook). Revive and federal agencies to artificially culture and rein- a tired or semi-conscious fish by gently flushing water troduce native fishes and improve their habitats are through its gills until it is able to swim normally. Only underway. take home the fish you need.

Fish Web Sites What Can You Do? Virginia Tech Department of Fisheries and Wildlife Your help is needed to foster healthy and diverse Sciences EFISH Virtual Aquarium, Fishes of Virginia: native fish populations, and to safeguard rivers and http://www.cnr.vt.edu/efish/ streams for future generations. One way to do this is to learn about fish, fish habitats, and the dangers they Fish Posters of the World: http://www.fishposters. face. You can also become a “river or stream watcher” com/index.html and promptly report any water pollution problems to Fishes of Iowa: http://www.state.ia.us/government/ your state natural resource agencies. dnr/organiza/fwb/fish/iafish/iafish.htm

Be alert to the following symptoms of water pollution: Fishes of Colorado: http://www.cnr.colostate. • muddy water, edu/~brett/fw300/flashcrd/splitflash.htm • oil slicks, Fishes of Texas: • fish and kills, • algae and weed problems, http://www.tmm.utexas.edu/tnhc/fish/index.html • odor and gas, Master Index of Freshwater Fishes: http://www.web- • unusual flows, cityof.com/mifftitl.htm • discolored water, • foaming water, and Snakehead Fish (Virginia Department of Game and • litter. Inland Fisheries): http://www.dgif.state.va.us/fishing/ snakeheads.html Fishing (Virginia Department of Game and Inland Fisheries): http://www.dgif.state.va.us/fishing/

5 Aquaria Web Sites Memphis Zoological Garden and Aquarium: http:// www.memphiszoo.org : http://www.mbayaq.org/ Tennessee Aquarium: http://www.tennesseeaquarium. Steinhart Aquarium: http://www.calacademy.org/ org/ aquarium/ Dallas Aquarium at Fair Park: http://www.dallas-zoo. The Aquarium: http://www.sptimes.com/ org/ Aquarium/ The Dallas World Aquarium: http://www.dwazoo. Waikiki Aquarium: http://waquarium.otted.hawaii. com/ edu/ San Antonio Zoological Gardens & Aquarium: http:// John G. Shedd Aquarium: http://www.sheddnet.org/ www.sazoo-aq.org/ National Aquarium in Baltimore: http://www.aqua. Sea World San Antonio: http://www.seaworld.com org/ Point Defiance Zoo & Aquarium: http://www.pdza. New England Aquarium: http://www.neaq.org/index. org/ flash4.html The Seattle Aquarium: http://www.seattleaquarium. Belle Isle Aquarium: http://www.detroitzoo.org/crit- org/ ters2.html New Jersey State Aquarium at Camden: http://www. Acknowledgements njaquarium.org/index2.php3 We greatly appreciate the editorial reviews of Dan Aquarium: http://wcs.org/home/zoos/ Goerlich, Barry Fox, and Nancy Templeman, Virginia nyaquarium/ Cooperative Extension, and the support of Randy North Carolina (Fort Fisher, Pine Knoll Rutan and Hilary Chapman, National Conservation Shores, Roanoke Island): http://www.ncaquariums. Training Center, U.S. Fish and Wildlife Service. com/ Art illustrations by Sally Bensusen, Mark Chorba, South Carolina Aquarium: http://206.74.146.33/ Mike Pinder, Karen J. Couch, and Duane Raver. scaquarium/scaweb/index.htm

Reviewed by Michelle Davis, research associate, Fisheries and Wildlife

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