Subsistence fisheries play a central role in the food security and socio-economic well-being of many Indigenous communities worldwide. However, because they are typically smaller in scale than commercial operations, they often lack access to the scientific information needed for sustainable management, despite facing similar biological complexities.
One such challenge is managing mixed-stock fisheries, where genetically distinct populations overlap in shared feeding grounds and contribute unequally to harvests. This complexity can enhance long-term catch stability through the portfolio effect, as asynchronous fluctuations in stock productivity buffer overall abundance. Preserving the genetic diversity that underpins this effect remains difficult, particularly for subsistence fisheries, which lack the tools available to larger-scale operations. As a result, Indigenous-led stewardship must navigate significant biological complexity to safeguard the long-term sustainability of these culturally important fisheries.
In the coastal Indigenous Cree communities of Eeyou Istchee (Quebec, Canada), subsistence fisheries target multiple anadromous populations of lake whitefish (Coregonus clupeaformis) and brook charr (Salvelinus fontinalis) during their summer feeding migrations. The extent of population overlap in this region, expected to be shaped by the spatial scale of migrations, remains poorly documented, leaving key aspects of marine population dynamics unresolved. This knowledge gap makes it difficult for Cree communities to assess whether a single management strategy can address the differing ecological and spatial dynamics of lake whitefish and brook charr.
In this Editor's Choice article, Bouchard and colleagues combined genomic tools (Genotyping-in-Thousands by sequencing, GT-seq) with Traditional Ecological Knowledge of fish distributions to unravel the contributions of distinct lake whitefish and brook charr populations to Cree subsistence harvests. Analyzing over 3,800 fish collected across five years along more than 400 km of James Bay's subarctic coastline, they provide the first high-resolution, landscape-scale insight into population overlap and contributions to fisheries, revealing patterns of migration and stock mixing critical for sustainable management. Their analysis shows that lake whitefish cover longer distances than brook charr during their migration, resulting in greater population diversity in mixed-stock samples. Despite these species-specific differences, both species exhibit consistent spatial patterns of stock overlap, with southern sites showing more similar compositions, suggesting broader inter-population mixing in this region. Overall, their findings indicate that intraspecific diversity is a defining feature of Cree coastal subsistence harvests and could help mitigate year-to-year fluctuations in the productivity of single stocks.
This study illustrates that even small-scale subsistence fisheries are ecologically complex, relying on both inter- and intra-specific diversity to maintain long-term stability. By integrating genomic analyses with Traditional Ecological Knowledge, Bouchard and colleagues demonstrate the power of collaborative approaches to uncover fine-scale population dynamics, offering insights that can inform the sustainable management of Indigenous and small-scale fisheries in other regions.
Read the full paper, A multi-species mixed-stock analysis reveals latitudinal differences in stock overlap with implications for supporting local indigenous fisheries, in ICES Journal of Marine Science.
