Babine Lake Sockeye Smolt Enumeration – Mark-Recapture

The Babine Lake Watershed is the principal sockeye rearing area for Skeena sockeye salmon, producing up to 90% of the sockeye returns to the Skeena River. This important watershed supports an average yearly harvest of 1.5 million sockeye in commercial (Canada and United States), recreational, and First Nations fisheries and an average escapement of 1 million spawning sockeye. There is a long history of intensive science and careful monitoring of salmon populations in the Babine Lake Watershed; the Department of Fisheries and Oceans (DFO) has counted adult sockeye returning to the Babine Lake Watershed at the Babine adult counting fence since 1946, and estimated the number of out-migrating sockeye smolts between 1959 and 2002 at a trap located at the outlet of Nilkitkwa Lake. The data from both the adult and smolt counting fences, and from the spawning channel fry counts, have historically allowed fisheries managers to estimate sockeye recruitment, and fry to smolt survival in the Babine Lake Watershed, but the Babine sockeye smolt counting fence was closed in 2002 due to government budget constraints. Available pre-2002 data shows a significant decline in some of the Babine sockeye population fry to smolt survival starting in the mid-1980s, and patterns of freshwater survival (fry to smolt survival) and marine survival (smolt to returning adult) of the Babine sockeye stocks have been unknown since 2002.
Babine sockeye returns have also declined significantly in numbers in the past two decades. The Babine Lake Watershed sockeye smolt population has been estimated by the Skeena Fisheries Commission (SFC) and Lake Babine Nation (LBN) since 2013, but we do not know yet to what extent the decreasing returns are due to freshwater versus ocean limitations. A continuous data set over multiple years is needed. The SFC, LBN, DFO, and Professor Jonathan Moore from Simon Fraser University propose to build on the project’s success since 2013, and continue using the Babine smolt enumeration facilities to provide sockeye smolt emigration estimates for the Babine Lake Watershed, to extend the data series analyzed by the DFO from 1959 to 2002, and now by the SFC and LBN since 2013. We believe that continuous data from the Babine smolt enumeration fence would provide important information on Babine sockeye population status, and basic information that will greatly contribute to understanding the large inter-annual variations in returns observed in the past two decades. An uninterrupted set of sockeye smolt population data over multiple years will help address one of the most fundamental questions of salmon stocks management–are freshwater or marine dynamics driving salmon returns?