Survival and Dispersal of Stocked Lake Sturgeon in a Large Northern River

Lake Sturgeon populations in the upper reaches of the Nelson River were assumed to be extirpated when stocking was initiated in 1994. Since then, 32,052 fingerlings (age 0; unmarked) and 2,444 yearlings (age 1; 2,341 marked with PIT tags) have been stocked near Sea Falls on the Nelson River in northern Manitoba. Based on recaptures of known (122 unique PIT tagged) and inferred (based on atypical growth chronologies) yearling stocked Lake Sturgeon in 2012 and 2013, a Lincoln-Petersen population estimate for the juvenile Lake Sturgeon in this reach as of 2012 was generated; post-stocking survival/retention was estimated at 27% (95% CI: 20 – 34%) for yearlings from the 2007 to 2010 cohorts. Relative recruitment success of yearlings was estimated to be ~17.4 times greater for fingerlings based only on PIT tag recaptures, and up to 130 times greater when the potential for PIT tag loss was accounted for. In 2013, 55 Lake Sturgeon were also captured in Pipestone Lake approximately 20 km downstream of Sea Falls; 41 (75%) fish had PIT tags, indicating downstream dispersal and subsequent survival of yearlings stocked at Sea Falls. Stocking yearlings has been effective in re-establishing juvenile Lake Sturgeon in the upper Nelson River.