In March, 1998 while searching the lake for a long lost aircraft that went missing nearly 60 years ago, an incidental but interesting discovery was made on the lake bottom. We failed to locate aircraft wreckage on this particular day, but as the search continued, we encounter many Burbot (Lota lota) , a freshwater cousin to the Pacific Cod, and observed some unusual excavations or holes on the lake bottom. Later, after further analysis and consultation with local underwater divers and fisheries biologists I have tentatively concluded the excavations are the work of Burbot.
The images shown below are still images captured from underwater video taken in March, 1998. They show two examples of the excavations found during the aircraft search. In both cases, the excavations, or burrows, have two entrances. Dimension lines and measurements have been added to the images to provide approximate scale.
Except for one observation made by an underwater
diver in 1997 while diving in Lake Laberge (B. Reynolds, personal communication)
excavations or tunnel burrows of this type have not been previously documented
in Canadian waters (C. Day, personal communication).
Underwater Video North returned to Lake Laberge in April, 1999 to further investigate this unusual phenomena. On this occasion the ROV was deployed along the east side of Richtofen Island where divers had observed large burrows on the lake bottom. Despite some technical difficults with thruster controls UVN was successful in a limited deployment and was successful in locating a tunnel burrow much larger than what had been document previously. In addition to this, large numbers of Burbot were also observed. The Burbot were very active and inquisitive about the ROV.
The following video still images show the large tunnel burrow that was found. The diameter of the larger excavation is estimated at about 2m and has a depth of about 1m. There is also on short tunnel off this large excavation to a smaller hole (visible on the right) about 40cm in diameter.
Lake Laberge offers excellent opportunities to observe and film Burbot. They seemed to be extremely curious about the ROV and would investigate it for several minutes at a time. After they had satisfied their curiousity they would move away and out of sight.
Prepared by D. Davidge
Acknowledgements: Perry Diamond and Harry
Lowry for coming out to help.