New Zealand Journal of Marine and Freshwater Research abstracts

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Aerial counts of spawning chinook salmon {Oncorhynchus tshawytscha) on the Rakaia River system, Canterbury, New Zealand, 1973-76

I. F. WEST¹

R. H. GOODE²

¹Fisheries Research Centre Ministry of Agriculture and Fisheries P.O. Box 297, Wellington, New Zealand

²23 Brent Place Christchurch 5, New Zealand

Abstract Aerial counts of chinook salmon in tributaries of the Rakaia River, South Island, New Zealand, were made several times in each spawning season from 1973 to 1976, and compared with concurrent ground counts. Smooth curves were fitted to the aerial counts and integrated to provide indices of abundance. Numbers of salmon were estimated by dividing these indices by estimates of the mean residence time offish. For the years 1973, 1974, 1975, and 1976 the numbers of salmon estimated to be in the areas counted were 4595, 5856, 14 222, and 16 702 respectively. Trap counts on one spawning tributary (Glenariffe Stream) made up between 7.6 and 15.5% of the spawning run. Such fluctuation in the proportion of the run in any one tributary may be due to the differing susceptibility of tributaries to flooding.

Keywords quinnat salmon; king salmon; chinook salmon; population estimates; Oncorhynchus tshawytscha; aerial counts; spawning; Rakaia River; New Zealand

New Zealand Journal of Marine and Freshwater Research, 1987, Vol. 21: 563-572 0028-8330/87/2104-0563$2.50/0 © Crown copyright 1987 Received 30 January 1986, accepted 14 January 1987

PDF file of entire paper: medium quality (757K); (scanned from paper original: notes about this process)

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