Investigating the sex-selectivity of a middle Ontario Iroquoian Atlantic salmon (Salmo salar) and lake trout (Salvelinus namaycush) fishery through ancient DNA analysis

Prior to European settlement, Indigenous peoples sustainably harvested Atlantic salmon (Salmo salar) and lake trout (Salvelinus namaycush) from Lake Ontario for centuries. Previous studies have suggested Indigenous peoples were able to maintain the productivity of Atlantic salmon and lake trout fisheries in the Great Lakes region through the use of resource management strategies. Since males tend to be the surplus sex among salmonids, one way in which Indigenous peoples could have managed Atlantic salmon and lake trout stocks was through the preferential harvesting of males. Here, we sought to investigate whether Indigenous peoples traditionally used sex-selective fishing to manage Lake Ontario Atlantic salmon and lake trout stocks. To address this question, we modified a DNA-based sex identification method developed for ancient Pacific salmonid (Oncorhynchus spp.) remains to make it applicable to archaeological Atlantic salmonid (Salmo spp.) and char (Salvelinus spp.) remains. This method assigns sex identities to samples through two PCR assays that co-amplify a fragment of the Y-specific salmonid master sex-determining gene (sexually dimorphic on the Y-chromosome gene) and an internal positive control, consisting of a fragment of the mitochondrial D-loop or nuclear clock1b gene. We applied this method to 61 Atlantic salmon and lake trout remains from the Antrex site (AjGv-38), a Middle Ontario Iroquoian (ca. CE 1250 to 1300) village located in the Lake Ontario watershed. Using this method, we successfully assigned sex identities to 51 of these remains (83.61% success rate), highlighting our method’s sensitivity and efficacy. Statistical analyses indicate neither the aggregate sex ratio nor the sex ratios obtained for the individual species were male-biased. This suggests Antrex’s Middle Ontario Iroquoian inhabitants probably did not practice male-selective fishing for Atlantic salmon or lake trout.