What are Lake Sturgeon populations in the KSNC reach like now?
While populations are lower than they were historically, Lake Sturgeon are still found throughout the KSNC reach of interest (from the Kelsey Generating Station downstream to the Nelson River estuary and in the Hayes River system). The following excerpts describing the Lake Sturgeon populations in the river reaches (bounded by generating stations) of interest to the KSNC have been adapted from ‘Lake Sturgeon in Manitoba: A summary of current knowledge’ (Manitoba Hydro 2016) and are supplemented by information provided by Indigenous Peoples. Please refer to the full document for more information on each section. Click on the coloured zones below for more information about sturgeon populations in that area.
By the time the Nelson River fishery was closed in 1960, the Lake Sturgeon population in this area was considered to have been depleted. Currently, the Kelsey GS prevents upstream movement of Lake Sturgeon, but genetic differentiation of populations upstream and downstream predates hydroelectric development. According to FLCN elders, Lake Sturgeon below Split Lake could move up and downstream to the estuary.
Population estimates have been conducted for the reach of river between Kelsey GS and Split Lake (426 adults estimated in 2015), the Burntwood River to First Rapids (570 adults in 2015) and Birthday Rapids to Gull Rapids (709 adults in 2016). No clear increasing or decreasing trend has been observed for any of the populations.
Juvenile and YOY (i.e., age 0) Lake Sturgeon have been captured in several discrete locations in the study reach, including the riverine section between the Kelsey GS and Split Lake, on the Burntwood River downstream of First Rapids (in low abundance), in Gull Lake (dominated by a single year class), and at the upstream end of Stephens Lake (also dominated by a single year class). Population estimates and juvenile inventories are conducted on an annual basis; refer to the Keeyask Monitoring reports for additional information.
The vast majority of contemporary knowledge about Lake Sturgeon in this reach originates from environmental studies completed in support of the Keeyask GS. Mark-recapture tagging, as well as acoustic telemetry studies, indicate that adult Lake Sturgeon tend to remain in the various water bodies in which they have been captured, but some movements (both upstream and downstream) at Gull Rapids and Birthday Rapids have been observed.
Recently, studies completed under the Manitoba Hydro Lake Sturgeon Stewardship and Enhancement Program (LSSEP) assessed the spawning and juvenile segments of the population in this reach. In spring 2012, only six adult (and one juvenile) Lake Sturgeon were captured near the base of the Kettle GS powerhouse and spillway, while in fall 2012, only ten juveniles were captured in the middle portion of the reach. These data were similar to results of previous monitoring studies completed in the 1980’s, 1990’s and early 2000’s, and it was reasoned that the low number of Lake Sturgeon available to spawn annually is likely one of the factors limiting population growth in the impoundment. Fox Lake elders (kitayatisuk) believe that the size of the Lake Sturgeon population currently in the reservoir is larger than the studies suggest and, thus, are of the opinion that the remnant population is a potential candidate for rehabilitation.
A total of 42 Lake Sturgeon have been captured during 13 fisheries surveys conducted in the Limestone Reservoir since its creation in 1989 (North South Consultants, unpublished data). While some of the Lake Sturgeon captured were younger than the age of impoundment, due to the low numbers of fish present it is considered unlikely that there is a self-sustaining population.
Studies conducted in support of the Limestone GS and proposed (no longer under consideration) Conawapa GS after 1988 revealed that the Lake Sturgeon population in this section of river was larger than previously thought. The Weir River, Angling River, and Lower Limestone Rapids have been confirmed as spawning locations, and successful spawning and hatch occurred at the Lower Limestone rapids in multiple years. YFFN (2013) reports that the lower Nelson River continues to provide fishermen with a populated and moderately accessible area for sturgeon fishing.
Based on an extensive mark-recapture data set dating back to the 1990s, the adult Lake Sturgeon population estimate in this area as of 2013 was 8,413, with a stable or slightly increasing population trajectory. Juvenile Lake appear to be concentrated in the vicinity of Jackfish Island; while one juvenile (age 2) was captured in the Nelson River estuary with limited effort , it is unclear to what extent juveniles utilize this area. Harvest on the lower Nelson River is thought to have increased since the construction of the Conawapa Road in the early 1990s.
The majority of sturgeon in the lower Nelson River inhabit a 65 km reach between Deer Island and the Lower Limestone Rapids and remain in this reach throughout the year. The reach has three known spawning locations and suitable YOY, juvenile and adult habitat. Acoustic telemetry data from 2007 suggested that less than 7% of the adult sturgeon in this reach will move upstream of Lower Limestone Rapids in a given year. Sturgeon in the reach are more likely to move downstream with at least 40% travelling as far as Port Nelson.
Some sturgeon move from the Nelson River into Hudson Bay and around Marsh Point into the Hayes River. Lake Sturgeon tagged in the Nelson River have been caught by SFN as far upstream in the Hayes River system as Sturgeon Lake in Ontario. According to Isaac Beardy in YFFN (2013) sturgeon “…don’t like saltwater… but can tolerate it…When the tide goes out they go around.”
The Hayes River system in the northeastern corner of Manitoba includes the Fox, Bigstone, and Gods rivers (tributaries to the Hayes River). Sturgeon inhabit the Hayes River mainstem, and numerous locations in the tributaries. Spawning has been reported at South Opuskiamishes River and at Red Sucker Rapids, with several other locations suspected but not confirmed. A Lake Sturgeon population in the Fox River between Great Falls and Rainbow Falls was estimated at 646 +/- 334 adults in 2004/2005.
Little is known about Lake Sturgeon in the Hayes River system, but its populations are believed to be healthy. In its 2012 Sturgeon Management Plan, Manitoba Sustainable Development noted that this could change if harvest pressures increase, as productivity (and carrying capacity) of these rivers are likely low. While Lake Sturgeon tagged in the lower Nelson River have been recaptured in the Hayes River system, high-resolution genetic analyses suggest that the Nelson River and Hayes River populations are distinct.