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Statistical Precision of Hydroacoustic Sampling of Fish Entrainment at Hydroelectric Facilities
Author(s) -
Johnson Gary E.,
Skalski John R.,
Degan Don J.
Publication year - 1994
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1994)014<0323:spohso>2.3.co;2
Subject(s) - stratified sampling , sampling (signal processing) , environmental science , entrainment (biomusicology) , statistics , hydroelectricity , sampling design , fish <actinopterygii> , hydrology (agriculture) , fishery , mathematics , ecology , computer science , biology , engineering , population , philosophy , demography , geotechnical engineering , filter (signal processing) , sociology , rhythm , computer vision , aesthetics
Hydroacoustic sampling can be an important technique for estimating fish entrainment rates at hydroelectric facilities applying for relicensing by the U.S. Federal Energy Regulatory Commission. Existing sampling procedures typically require daily monitoring of entrainment over at least one annual cycle. To investigate potential cost savings through the use of probability sampling, three data sets consisting of daily hydroacoustic estimates of entrainment for at least l year were reanalyzed to determine the effects of subsampling on the precision of seasonal and annual estimates of fish entrainment. The study sites were located in New York, Wisconsin, and South Carolina. When a stratified random sample of days within each month was used, a 50% subsample of days (i.e., 15 d/month) resulted in a sampling precision of approximately ±22.0% of the true value of annual entrainment at the New York site, ± 14.3% at Wisconsin, and ±9.6% at South Carolina, 95% of the time, Sampling 20 d/month resulted in a precision of ± 15.5%, ± 10.0%, and ±6.7%, respectively, 95% of the time, Substantial cost savings appear possible through the use of stratified random sampling designs that provide a level of precision sufficient for both management and relicensing decisions.