Kootenai River Fisheries Investigation; Stock Status of Burbot, 2004-2005 Annual Report.

Paragamian, Vaughn L. ; Laude, Dorothy C.

Idaho. Department of Fish and Game.

关键词: Canada;    British Columbia;    Burbot - Kootenai River - Statistics;    Rivers;    Fisheries;   

DOI  :  10.2172/901206
RP-ID  :  DOE/BP-00004691-8
RP-ID  :  00004691
RP-ID  :  901206

美国|英语

来源: UNT Digital Library

【 摘 要 】

The main objective of this investigation was to monitor movement and spawning activity of burbot Lota lota in the Kootenai River, Idaho and British Columbia, Canada during the winter of 2004-2005. As a secondary objective, we examined the literature to obtain inferential information on how changes in historic water temperature may affect burbot movement and spawning. Discharge from Libby Dam for October 2004 ranged from 133 to 272 m{sup 3}/s, was ramped up to 532 m{sup 3}/s early in November, then was brought down to about 283 m{sup 3}/s through the last 10 days of the month. In early December 2004, discharge was brought up to full powerhouse of about 762 m{sup 3}/s several times but remained above 436 m{sup 3}/s for most of the month. However, with the prospect of a below normal snowpack and a mild winter, discharge was brought down to 113 m{sup 3}/s, minimum flow, for the remainder of January through March 2005. Discharge did not meet the systems operation request as a burbot rehabilitation measure. Mean water temperature of the Kootenai River at Libby Dam from November 1, 2004 through April 5, 2005 was 5.3 C, ranging from 10.45 C on November 1, 2004 to 3.2 C on March 2, 2005. Tributary water temperatures were monitored in Deep, Smith, and Boundary creeks in Idaho and in the Goat River, Corn, and Summit creeks, British Columbia, Canada from November 1, 2004 to about April 18, 2005. Baited hoop nets of 25 and 19 mm bar mesh were fished from November 5, 2004 through April 4, 2005 for 2,046 net d (one net day is a single 24 h set). One hundred twenty-two fish were caught encompassing ten different species of fish. Eighteen burbot (14 different fish) were captured. Sixteen of the captures were at Ambush Rock (rkm 244.5), one was near Nicks Island (rkm 144.5), British Columbia, and the other was downstream of the Goat River (rkm 152.7). Of the 18 burbot captured, one fish escaped from the net overnight, four were recaptures from this year's study, six were recaptures from previous years, and seven were new fish. Of the recaptures, five were tagged the previous year with an external sonic transmitter (all tags were shed), and one recapture was a fish tagged in February of 2001 at the Goat River with an internal sonic transmitter. Hoop net catch per unit effort for burbot was 0.009 fish/net d or 111.1 net d/fish. Burbot total length ranged from 489 mm to 764 mm TL (mean = 615.7 mm, SD = 74.6 mm, n = 13). Burbot weight ranged from 867 g to 2,798 g (mean = 1695.8 g, SD = 555.5 g, n = 13). Our literature review indicated even subtle changes in temperature can cause a variety of changes in life history patterns and in some cases seriously alter the outcome of spawning and recruitment. Furthermore, results from a summary study of burbot from our investigations and this one indicated the effect of temperature on burbot behavior is modified by river discharge, but the two combined have probably altered the historic movement patterns of burbot, because temperatures are now warmer with higher river discharges.