1. Burbot Findings

2. Number of Burbot Captures
Sampling Season
Number of Burbot Captures
Total Net Days
CPUE (fish/net day)
Wtr. 1993: Mar May 1993 17
554
0.031
Wtr. 1994: Oct April 1994 8
910
0.009
Wtr. 1995: Nov Feb. 1995 33
689
0.048
Wtr. 1996: Nov Mar. 1996 28
496
0.056
Wtr. 1997: Oct Mar. 1997 23
1,061
0.022
Wtr. 1998: Oct May 1998 42
1,241
0.034
Wtr. 1999: Oct April 1999 44
1,454
0.030
Wtr. 2000: Oct April 2000 36
1,713
0.021
Wtr. 2001: Oct Mar. 2001 73
2,085
0.035
Wtr. 2002: Oct April 2002
1,530
0.011
Wtr. 2003: Oct Mar. 2003 11
1,810
0.006
Wtr. 2004: Nov Mar. 2004 19
1,965
0.010
Wtr. 2005: Nov April 2005 18
2,046
Wtr. 2006: Oct. 2005–Mar. 2006 14
2,000
0.007
Wtr. 2007: Nov Mar. 2007a 2
1,497
0.001
Totals
385
21,050
0.018
Mean
0.024

3. Systems Operation Request

4. Sinclair Lake
Extensive Burbot Rearing - to answer the
Question of the best method to rear burbot
to fingerling size for stocking?

5. Map of Sinclair Lake showing collection locations.

6. Four Incubators
2 L bottle
Deployed under the
Ice and at about 1.6 m
depth

7. 100,000 eyed embryos into lake
1,000 eyed embryos/incubator

8. 3/15/07 Embryo Release Water Qual. Date 03/12/07 03/15/07 04/12/07
05/23/07
06/06/07
06/25/07
Surf
1.6 m
Ammonium (NH4) (mg/L)
0.10
0.09
0.05
0.07
0.03
0.33
0.04
0.02
Nitrate (NO3)
(mg/L)
1.46
1.66
1.13
0.99
0.80
0.97
0.82
0.89
2.79
1.58
1.78
1.82
Percent Dissolved Oxygen (%DO)
6.7
3.4
44.2
15.5
90.3
82.0
90.6
88.6
89.6
90.2
90.8 86
Dissolved Oxygen (DO) (mg/L)
0.81
0.38
4.33
8.2
8.16
7.49
7.4
6.9
6.94
6.59
Temperature (Co)
1.5
3.09
1.3
2.87
11.6
5.43
15.9
15.69
19.46
19.5
22.5
8.94

9. High powered scientists at work.

10. Extensive Rearing Incubation Jar resultsID
Number
Set date
Pull date
Water temp.
(Co)
Live eggs at pull
Dead eggs
at pull
Egg shells
Larvae
(N)
Therm. units
(degree days)
Est.
hatching
based on
larvae
(%)
based on
egg
shells (%) 1
3/15/07
3/22/07
1.3 89 -- 7 11
142
1.10
0.07 2
4/02/07
130 33 5
186
0.38
3.0 3
4/09/07 96 22
220
2.2 4
4/24/07 50 48
324
0.40
4.8
Total
365
110 20
0.05a
2.75
In the lab about average of 65% were eyed and > 50% hatching success.
Low DO may have resulted in high mortality, 3.8 ppm – predators were also
present.

11. Robert Fredericks pond
Extensive Rearing 2008
Robert Fredericks pond
Release larval burbot after
mouth has developed and after
they have begun feeding on
dry diet.

12. Burbot Demographics

13. Population Estimates 1997-2006
Survival = 38%

14. Burbot Recruitment Estimates

15. A Rehabilitation Goal for Kootenai River Burbot
We have no idea what the population number was
Pre-Libby Dam
But we do have CPUE and Population estimates
We could use CPUE from Alaskan Rivers in a model
We use our CPUE – N model and an Alaskan CPUE
to predict what N would be based on their population
densities!

16. For Example
Y = a + bX

17. Recovery Goal for Burbot over 350mm
Y = a + bX
CPUE = (Pop. est.)
CPUE of 1.0 for Alaskan Rivers
1.0 = (pop. est.)
At a CPUE of 1.0 the
Pop. Est = 9,500 burbot over 350MM

18. Analysis Yet to be completed
Ordinary Least Squares assumes no error in the variables
Errors in Variables Model needs to be tested

19. Population Viability Modeling
What level of Recruitment is necessary to
reach Rehabilitation Goal in
25 years?
50 years?