Lake Babine Nation Fisheries (LBNF) plans to work with Fisheries and Oceans Canada (DFO) to continue the investigation of the behaviour and ecology of Babine River sockeye fry. The proposed project is composed of four relatively discrete components which include:
- early life history behaviour and migration;
- extent and rate of predation on juvenile sockeye;
- egg-to-fry and fry-to-smolt survival, frequency of occurrence of disease and parasites and condition as a function of length and weight; and
- presence and behaviour of sockeye fry rearing in downstream slow water habitats to obtain evidence of a riverine juvenile sockeye ecotype.
Other observed adverse effects that may affect sockeye fry survival and overall sockeye production will be documented. These studies are intended to address the diminished abundance of Late Run Upper and Lower Babine River sockeye in their juvenile freshwater environment.
A sockeye enhancement program has been ongoing at Tatsamenie Lake since 1990. A review of the program was funded by the Northern Fund in 2005, and in 2008, the Northern Fund began supporting the Extended Sockeye Fry Rearing Project.
The fry were originally reared in lake pens, but because of a devastating disease outbreak, the project shifted to onshore rearing systems beginning in 2009. The egg to smolt survivals of the fed fry have been variable but have ranged from 10% to 70%, or 5 to 15 times compared to wild fry, depending on fry behaviour after outplanting. Assessment of adult production from this project is ongoing. Smolt to adult survivals of the reared fry will be definitively determined with the return of the corresponding adults in the coming years, but to date, the adult production from reared fry has been lower than expected. This project continues to test a technique that has the potential of increasing production for other small scale sockeye salmon enhancement projects as well as rebuilding the Tatsamenie Lake sockeye stock in low brood year cycles.
Also at Tatsamenie Lake, the Canadian Department of Fisheries and Oceans began a smolt enumeration program in 1996, and this ran continuously from 1998 through to 2011. The Northern Fund began supporting this program in 2012, and the two programs were combined in 2015. The combination allowed the Tatsamenie Lake sockeye smolt mark-recapture project to extend beyond its previous end date of June 30, through to the second week of September. This provides a more accurate smolt population estimate as well as increased precision of the estimated enhanced sockeye survival and production. This also allows for monitoring of potential early out-migration of the reared fry.
Babine Lake sockeye salmon comprise the bulk (90%) of Skeena River sockeye captured in Canadian and U.S. waters, and were historically a major bi-lateral economic driver on the North Coast. Any reductions in returns significantly affect fisheries and subsistence in both countries.
The worrisome trends observed in freshwater survival, and routinely depressed escapements over the past ~20 years, highlight the critical importance of understanding the modern freshwater ecology of Babine Lake sockeye salmon and their nursery habitat. The fundamental ecological changes observed in Babine Lake in 2013 (changes in nutrient availability likely due to climate change, and resultant shifts in the food web) indicate a heightened need for long-term data to assess specific mechanisms of lake change and stock decline, such that informed decisions can be made to guide fisheries resource management, salmon enhancement, and habitat stewardship. As such, the current project consists of lake-wide limnological assessments, surveys of juvenile sockeye abundance, size, feeding ecology, physiological condition and freshwater survival, and an implementation of a spatially-resolved multiple trophic level paleolimnological food web assessment over the last 200 years (or more).
While Fraser River sockeye salmon survival has declined over the past decade, it has also exhibited high interannual variability. The processes responsible for this trend and the variability are not understood and require investigation. This project builds on the previous work by adding a fifth year of sampling juvenile migrants immediately prior to their entry into the Strait of Georgia (SoG). The sampling platform will be identical to that employed successfully in 2013-2015, and GSI analysis will help to provide estimates of relative abundance and migration timing past Mission by stock. It is anticipated that sampling intensity in 2016, a juvenile Pink Salmon outmigration year, will be similar to that in 2014. In 2016, we propose to repeat the 2014 & 2015 study design and parameters assessed, including the assessment of the nocturnal migration patterns of Sockeye juveniles for a third year.
As in previous years, samples collected under this project will be compared to samples collected in other ongoing and proposed assessments, such as DFO’s annual SoG trawl survey occurring June-July and a similar trawl survey in Johnstone Strait. In combination, these three studies will add a third year to a comprehensive multi-stock assessment of Fraser River juvenile sockeye salmon relative abundance and condition, from nursery lake exit through early marine near-shore residency.
Sub-yearling ocean-migrant sockeye salmon (e.g. Harrison River stock) can be important contributors to Fraser River Sockeye production. The 2016 survey will continue to incorporate the bio-sampling of captured sub-yearling juveniles to identify their contribution, and migration timing at Mission by Conservation Unit (CU).
Lastly, the 2016 project will explore the feasibility of deploying an acoustic Doppler current profiler in an attempt to measure water current velocities over a depth range. This information may be important in determining absolute juvenile sockeye abundance at Mission.