Burbot Findings 2006-2007

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

Systems Operation Request

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

Map of Sinclair Lake showing collection locations.

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

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

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

High powered scientists at work.

Extensive Rearing Incubation Jar results ID 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.

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.

Burbot Demographics

Population Estimates 1997-2006 Survival = 38%

Burbot Recruitment Estimates 1997-2006

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!

For Example Y = a + bX

Recovery Goal for Burbot over 350mm Y = a + bX CPUE = 0.003 + 0.0001(Pop. est.) CPUE of 1.0 for Alaskan Rivers 1.0 = 0.003 + 0.0001(pop. est.) At a CPUE of 1.0 the Pop. Est = 9,500 burbot over 350MM

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

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