| Summary: | The salmon life cycle begins in freshwater streams when adult salmon spawn, leaving fertilized eggs which hatch in the stream. Juvenile salmon migrate downstream to the ocean, where they spend several years until they reach reproductive age. Upon reaching sexual maturity, they return to their natal streams to spawn. The number of mature salmon migrating from the marine environment to freshwater streams is defined as escapement. Escapement data are the enumeration of these migrating fish as they pass upstream, and are a widely used index of spawning salmon abundance. These data are important for fisheries management, since most salmon harvest occurs near the mouths of rivers where salmon spawn during this migration. Escapement data are collected in a variety of ways. Stationary projects utilize observers stationed along freshwater corridors who count salmon as they pass upriver through weirs or past elevated towers. Sonar equipment placed in the river can also give a stationary escapement count. These counts usually represent a sample, and are expanded to represent a 24h period. Escapement data can also be collected using aerial surveys, where observers in an aircraft provide an index to estimate escapement. In general, escapement counts do not represent total abundance, but instead an index of abundance. Surveys are usually timed to coincide with peak spawning activity, generally in the summer, but in the case of Coho salmon in the fall as well. The data included in this package are extracted from the Fish Counts tab under the Sport fishing section on Alaska Department of Fish and Game's website (http://www.adfg.alaska.gov/sf/FishCounts/). The R script (SportFish_master_cleaning.R) included in this package merged all the data into one file (SportFish.csv) and reformatted all the data: the year and month/day columns were merged into a single date column; trailing spaces from species, region and location columns were removed; run information from the species name column was moved into a new run type column. The file sportfish_locs.csv contains region information for unique locations in SportFish.csv.
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