Kootenai River White Sturgeon Investigations and Experimental Culture, 1990-1991 Annual Report PDF Download

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Languages : en
Pages : 59

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Book Description
Setline and angling techniques were used to sample 56 white sturgeon Acioenser transmontanus from the Kootenai River in 1991. Of those sampled, nine were recaptures from previous years of this study. A total of 382 white sturgeon were captured from March 1989 through October 1991. Fork lengths of white sturgeon in the sample ranged from 88-274 cm. Our data indicated there was a complete lack of recruitment of juveniles into the population. The youngest fish sampled was of the 1977 year class. The population was estimated at 880 individuals with a 95% confidence interval of 638 to 1,211. Annual mortality of white sturgeon since 1982 is 3.74%. Approximately 80% of the population was more than 20 years old and was reproductively mature. Surgical examination of 309 white sturgeon since 1989 indicated that approximately 7% of the female white sturgeon and 30% of the male white sturgeon are reproductive each year. The ratio of males to females was estimated at 1:l. White sturgeon sampled and released with and without surgical examination were recaptured at equal rates. An ongoing sonic telemetry study has documented long distance movements by adults. White sturgeon regularly move across the British Columbia - Idaho border. White sturgeon seek out deep holes in the river or migrate to Kootenay Lake during late fall, During spring and early summer of both 1990 and 1991 reproductively mature white sturgeon moved from 15 to 110 km upriver and congregated within 10 km downriver from Bonners Ferry in areas of elevated water velocity. This behavior coincided with increasing discharge and water temperatures. Developing white sturgeon eggs were recovered from the river near Bonners Ferry on July 3, 1991. Contamination of eggs by organochloride compounds were less in recent samples from the Kootenai River than in a single sample collected in 1982. White sturgeon eggs from the Kootenai River fish contained approximately one tenth the organochloride compounds of white sturgeon eggs from the lower Columbia River.