Media release

From: Springer Nature

Assessing the impacts of heatwaves on top marine predators 

The effects of 4 recent heatwaves in the Northeast Pacific on the distributions of 14 apex predator species — such as sharks, whales, seals and turtles — are modelled in a study published in Nature Communications. The findings may provide insights into how predator responses vary across marine heatwaves and may aid the development of tools to predict marine predator distributions in near real-time.

Marine heatwaves are extreme short-term warming events with widespread ecosystem and socioeconomic impacts. Previous studies have examined long-term redistributions of marine species in response to climate change. However, less is known about short-term responses to episodic events like marine heatwaves, limiting our ability to proactively manage their socioecological impact.

Heather Welch and colleagues used machine learning and data from tagged animals to understand how apex predators in the Northeast Pacific redistribute themselves in response to marine heatwave events. The authors modelled the effects of 4 recent marine heatwaves (in 2014, 2015, 2019 and 2020) in the Northeast Pacific on the distributional responses of 14 marine predators — including sharks, mammals, seabirds, turtles and tunas. Predator responses were found to be varied but highly predictable, demonstrating a capacity for early warning systems of heatwave impacts, similar to weather forecasts.

Some species experienced near-total loss of habitat, such as bluefin tuna and blue shark during the 2015 heatwave, while others experienced a two-fold habitat gain, such as California sea lion and elephant seal during the 2019 heatwave. Certain species also redistributed across jurisdictional boundaries with the USA receiving the largest influx of species during marine heatwaves. This could lead to new management risks and responsibilities but also economic opportunities. For example, 11–31% of albacore, bluefin and yellowfin tuna habitat shifted from Mexico to the US during the 2014 and 2015 heatwave events.

As adaptive management tools are needed to prepare nations and minimize future fishery conflicts, the authors also demonstrate a dynamic ocean management tool using their models that can produce daily predictions of the distribution for each species. This early warning system would allow for proactive responses to new human-wildlife conflicts and changes in the availability of marine resources.