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Glossary A
abiotic
The non-living components of a fish's habitat such as substrate, large woody debris, shade, and water quality.
adaptation
An alteration or adjustment in structure or habits, often hereditary, by which a species or individual improves its condition in relationship to its environment.
adipose fin
The small, rayless fin along the midline of a fish's back behind the dorsal fin. Often times, this fin is removed as a marking technique.
affluvial
A fish that is spawned in a small tributary, rears for a period of time in the tributary (1-4 years), and then migrates out to a lake where it matures. The fish then migrates back to the tributary to spawn.
alevin
Young fish; fry.
amphidromous
A life history strategy where young fish rear in freshwater, migrate to saltwater to grow and mature, and then return to freshwater to spawn as adults. The steelhead trout is an example of a species that uses this particular life history strategy.
anadromous
A life history strategy where young fish rear in freshwater, migrate to saltwater to grow and mature, and then return to freshwater to spawn as adults. The steelhead trout is an example of a species that uses this particular life history strategy.
anchor ice
Ice that forms on the bottom of a stream during winter. Anchor ice is formed by the accumulation of frazil ice (ice formed in the stream water column). Anchor ice does not allow fish to get between rocks on the bottom of the stream (substrate) and inhibits fish from feeding on invertebrates.
anchor tag
An alpha-numeric or color-coded, external tag injected near the dorsal fin of the fish. Because of its location, the tag is easy to identify by anglers and biologists.
anesthetic
A chemical such as MS-222 or clove oil used to reduce a fish's movement (similar to putting a human patient to sleep), often administered prior to a transmitter surgery.
aquatic
Consisting of, relating to, or being in water: an aquatic environment.
Living or growing in, on, or near the water: aquatic animals and plants.