Historically, Meziadin Lake has been the largest producer of sockeye salmon in the Nass River watershed. Between 1982 and 2016, the overall average annual escapement of Meziadin Lake sockeye salmon declined, with an especially notable downward trend in annual escapement since 2010. Similarly, since 1982 the proportion of Meziadin Lake sockeye salmon as a proportion of the total Nass River aggregate population has decreased an average of 3-13% per decade, with the largest decrease occurring in the last ten years. A variety of factors can contribute to declining stocks, including biological or habitat constraints to freshwater productivity. Biological limitations to the production of sockeye salmon in Meziadin Lake have been the subject of fisheries management discussions for decades, and historically the limnology of Meziadin Lake was relatively well-studied compared to other systems in the region. In 2002, Fisheries and Oceans Canada (DFO) recommended that in years of low spawner abundance (<100,000), Meziadin Lake limnology should be assessed throughout the growing season and fall-fry abundance and age composition obtained to further explain factors affecting fry growth and survival (Bocking et al. 2002). However, despite recommendations in 2006 by DFO Core Stock Assessment Program to establish a comprehensive sockeye lakes research program throughout the BC north coast, many of these programs were discontinued. As a result, comprehensive seasonally-resolved limnology surveys in conjunction with an evaluation of production capacity have not been conducted on Meziadin Lake since 2001. The ongoing decline in sockeye salmon escapement to Meziadin Lake warrants updated information on potential limiting factors to freshwater productivity.
The objectives of our proposal are to identify potential limitations to freshwater productivity within Meziadin Lake by providing updated estimates of sockeye salmon production capacity and habitat status. To achieve these objectives, we will collect limnological, hydroacoustic, zooplankton population and limnetic fish data throughout the growing season and use a bioenergetics model to estimate net juvenile sockeye productivity and habitat carrying capacity. Results will also provide updated information on the evolution of limnological conditions throughout the growing season and how those patterns may influence short and long-term freshwater productivity, as well as inform future development of habitat benchmarks for Meziadin Lake.