Chinook salmon predation by pumas in Patagonia: ecological implications of a novel trophic interaction

Invasive species can affect ecosystems by altering nutrient cycling, resource competition, predator-prey dynamics, and other ecological interactions. In Patagonia, invasive Chinook salmon (Oncorhynchus tshawytscha (Walbaum, 1792)) have established self-sustaining populations in numerous river basins over the past 45 years, transferring marine-derived nutrients into freshwater and terrestrial ecosystems. Opportunistic scavenging of salmon carcasses has been documented in Patagonia, but not active hunting by apex predators. Here, we document the first recorded instance of pumas (Puma concolor (Linnaeus, 1771)) preying on adult Chinook salmon in the Caterina River basin (Los Glaciares National Park, Argentina). Camera traps and field surveys revealed at least two juvenile pumas actively hunting salmon and leaving distinctive carcass remains. Spatial analysis showed puma activity concentrated near salmon spawning grounds, suggesting that pumas may respond behaviorally to seasonal salmon availability. This behavior, unreported in the scientific literature in the Northern Hemisphere despite sympatry between salmon and puma, may reflect differences in landscape structure, predator communities or prey accessibility. Our findings highlight the potential for invasive species to reshape predator ecology and nutrient flows in ways that both parallel and diverge from patterns observed in native ecosystems.