Glossary
Age Class
Age at maturity, which may differ among fish of the same year class. For example, among wild Snake River spring Chinook born in 2003, 8% may mature as jacks,
73% after 2 years in the ocean, and 19% after 3 years.
Aleutian Low
A semi–permanent, subpolar area of low pressure located in the Gulf of Alaska near the Aleutian Islands. It is a generating area for storms, and migratory lows often reach maximum instensity in this area. It is most active from late fall to late spring. During summer, it is weaker, retreating toward the North Pole and becoming almost nonexistent. During this time, the North Pacific High pressure system dominates (NOAA National Weather Service). Courtesy of NOAA National Weather Service.
California Current
The California Current System (CCS) is a southward–flowing ocean current found along the west coast of North America, beginning at the northern tip of Vancouver Island, Canada, and ending near the southern tip of Baja California/Mexico. It is one of four elements of the anticyclonic North Pacific Gyre. The North Pacific Gyre includes the southward–flowing California Current, the westward–flowing North Pacific Equatorial Current (which flows toward Japan), the Kuroshio Current (which flows north along Japan) and the North Pacific Current (which flows eastwards towards North America).
CPUE
We define catch per unit effort (CPUE) as the number of a particular species caught per kilometer traveled with the trawl under tow. However, CPUE is a relative and indirect measure of fishing effectiveness or species abundance. "Catch" can mean weight or numbers of total catch or of a particular species. "Units of effort" can be measured as individual cruises, the number of sets of a fishing net (or casts of a line), or as units of time or distance.
Geostrophic Wind
A wind that is affected by coriolis force, blows parallel to isobars and whose strength is related to the pressure gradient (i.e., spacing of the isobars). Courtesy of NOAA National Weather Service.
Escapement
For salmon, the proportion of a population that returns as an adult to spawn in the natal stream (having "escaped" the catch in ocean fisheries).
Jack
A "Jack" is a male Chinook or coho salmon that returns to spawn prematurely, before growing to the size of a normal adult. Jacks stay in the ocean from a few months to a year, returning to the natal stream 1–2 years before normal adults of their age class. Thus numbers of returning jacks are sometimes used as a basis to predict run size the following year.
Northern California Current
The Northern California Current (NCC) is generally taken to be that part of the California Current that lies between the northern tip of Vancouver Island and the Oregon–California border, between Cape Blanco OR/Cape Mendocino CA. This portion of the CC shows a generally weak meandering flow year–round, which more–or–less flows parallel to the coast. It is characterized by strong seasonality in winds, upwelling, and biological productivity. Winter winds in the NCC are usually from the south or west, whereas summer winds are from the north and cause coastal upwelling.
North Pacific High
The North Pacific High pressure system is the region of high sea-level pressure that occurs over the eastern North Pacific Ocean in the climatological mean as shown in Figure 1 (Mass and Bond 1996).icon
Oblique Tow
A tow made by pulling the net at a slow tow speed from the sea floor to the surface. Under this configuration, the angle between the net and sea floor is maintained at 45 degrees.
OPIH (Oregon Production Index, Hatchery)
For coho, an estimate of total freshwater escapement, adjusted for ocean and freshwater catch, for public hatchery fish throughout the Oregon Production Index Area. Private hatchery production is removed from this estimate, so it reflects only public hatchery fish. Used as the numerator in calculating SARs for the OPIH.
Recruitment
Number or proportion of biomass added to a fish population as a result of growth or reproduction, especially for a given year class.
Secchi Disk
A device to measure the turbidity (transparency) of the upper water column. A 30–cm diameter white disc is lowered slowly through the upper water column to the point at which the pattern is no longer visible. The depth of the disk is then taken as a measure of transparency or turbidity.
SAR (smolt–to–adult ratio)
For a population of salmon, the number that survived to migrate to the ocean as juveniles divided by the total number (all age–classes combined) that returned as adults.
Teleconnection
The term "teleconnection pattern" refers to a recurring and persistent, large–scale pattern of pressure and circulation anomalies that spans vast geographical areas. Teleconnection patterns are also referred to as preferred modes of low–frequency (or long time–scale) variability. Courtesy of the NOAA National Weather Service Climate Prediction Center.
Transmissometer
A device for measuring beam attenuation, which can be used as a measure of turbidity in water. A beam of light is cast through the water and the transmissometer records the measure of light at a given point past the source of the beam.
Year Class
Fish of the same species and stock that are born in the same year.
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