Angler – A person who fishes.
Aquatic nuisance species – A species that threatens native species' abundance or diversity, stability of aquatic systems and commercial or water recreational use.
Asexually – Having no sex or sexual organs; not involving the union of male and female germ cells.
Bleach solution – (10-50% bleach solution) – A mixture of water and chlorine bleach. A 10% bleach solution is 1 part bleach to 9 parts water. Washing fishing gear with a bleach solution can kill microorganisms, including non-native microorganisms, and prevent their spread between river systems.
Catch and release – A method of recreational fishing in which the angler immediately returns the fish (s)he has caught back to the water in which it was caught.
Dorsal fin – The main fin located on the back of fishes and certain marine mammals.
Ecosystem – A dynamic complex of plant, animal, and micro-organism communities and their non-living environment interacting as a functional unit.
Exotic – A species that is not native to a region.
Fluvial Arctic Grayling – A river-dwelling member of a freshwater fish species in the salmon family that is often identified by its large, sail-like dorsal fin. Fluvial Arctic grayling are Arctic grayling populations that live and spawn in rivers and streams as opposed to lakes. Fluvial Arctic grayling are native to Yellowstone National Park and are rare in the park. Scientific name: Thymallus arcticus.
Gillnetting – To catch fish by means of a gillnet – a fishing net set vertically in the water so that fish swimming into it are entangled by the gills in its mesh.
Hybrid – The offspring of genetically dissimilar parents or stock.
Native species – Indigenous or occurring naturally in a given geographic area and not introduced to that area by humans.
Mountain whitefish – A species of freshwater fish in the salmon family. A native of many western American mountain streams and lakes, Mountain whitefish are a silver, generally bottom-feeding fish that require deep pools and clean water. Mountain whitefish are native to Yellowstone. Scientific name: Prosopium williamsoni.
New Zealand Mud Snail – A small snail, native to New Zealand and non-native to the United States, that was first discovered in rivers near Yellowstone in the late 1980s. They can reproduce quickly and mass in high densities, crowding out food sources for native fish and altering the physical characteristics of rivers and streams. Scientific name: Potamopyrgus antipodarum.
Niche – A unique ecological role of an organism in a community.
Parasite – An organism that lives in or on the living tissue of a host organism at the expense of that host.
Trout – The common name given to a number of species of freshwater fishes belonging to the salmon family, Salmonidae.
Brook trout – A species of freshwater fish in the salmon family. It is native to a wide area of eastern North America, including most of Canada from the Hudson Bay basin east, the Great Lakes–Saint Lawrence system, and the Mississippi River drainage in the United States as far south as northern Georgia. It is not native to Yellowstone National Park. Scientific name: Salvelinus fontinalis.
Brown trout – A species of freshwater fish in the salmon family. The Brown trout is native to Europe and was introduced to North America. It is not native to Yellowstone National Park. Scientific name: Salmo trutta fario.
Cutthroat trout – A species of freshwater fish in the salmon family. A native of many Rocky Mountain rivers, the cutthroat has a crimson marking under its jaw that inspired its common name. The Yellowstone Cutthroat trout, Westslope Cutthroat trout and Snake River Cutthroat trout are the three subspecies of the cutthroat trout that are native to the Yellowstone region. Scientific name: Oncorhynchus clarki.
Lake Trout – A species of fish in the salmon family; a freshwater char living mainly in lakes in northern North America. It is not native to the Yellowstone ecosystem. Other common names for it include Lake char, Touladi and Grey trout. Scientific name: Salvelinus namaycush.
Rainbow trout – A species of Pacific salmon native to tributaries of the Pacific Ocean in Asia and North America. It is not native to Yellowstone National Park. Scientific name: Oncorhnchus mykiss.
Whirling Disease – A disease caused by a microscopic parasite that affects fish in the trout and salmon family. By damaging cartilage and placing pressure on the nervous system, whirling disease can kill young fish directly, or cause infected fish to swim in an uncontrolled whirling motion. This can make it impossible for them to escape predators or to effectively seek food. The whirling disease parasite was introduced to the United States from Europe in the 1950s and has spread to many streams across the United States. Scientific name: Myxobolus cerebralis.
Vertebrates – An animal that has a backbone.