Impacts of a warming climate on Atlantic salmon mortalities in recreational fisheries

What is it about?

The average global temperature has consistently on the rise owing to climate change, and is projected to further increase by around 1.8 to 4 °C by 2100. This is especially concerning for organisms inhabiting both land and water. The Atlantic salmon, one such species of fish, is important for commercial, recreational, and subsistence fisheries. Thanks to its poikilothermic nature (an inability to regulate one’s body temperature metabolically, as seen in most fishes), the warming waters leave this fish particularly vulnerable, even during recreational catch and release fishing. The authors of this paper developed a model to predict the probability of mortality in caught and released Atlantic salmon in warming rivers. They used published data from Canada and other Atlantic countries to establish current species mortality rates, regional and temporal trends in river temperatures, and closure protocols owing to temperature changes.

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Photo by Hunter Brumels on Unsplash

Photo by Hunter Brumels on Unsplash

Why is it important?

Catch and release angling is considered sustainable for fisheries management, having minimal fish mortality after release. However, the decline in Atlantic salmon populations raises concerns regarding the suitability and perils of this practice in the midst of climate-induced temperature variations. Catch and release fishing in warm waters with low dissolved oxygen can completely exhaust the salmon during capture, and disrupt its physiological functions, either decreasing its chances of recovery upon release or making it more vulnerable to predation and diseases. KEY TAKEAWAY According to the model, a positive correlation is observed between the probability of Atlantic salmon mortality and water temperatures during catch and release. These mortalities are low at cool river temperatures (<12 °C) and increase with rising temperatures (>18 °C). Consequently, this study emphasizes the need to incorporate climate-responsive adaptive management for recreational catch and release fisheries. It also underscores the importance of educating anglers about best practices and ideal conditions for sustainable catch and release.