In a new study published in Conservation Biology, an international team of over 300 marine scientists from 51 countries – including BioSS researcher Phil Bouchet – has identified and assessed the major threats that need to be addressed to support the conservation of marine megafauna worldwide.

The research assessed the vulnerability of 256 marine megafauna species including whales, sharks, bony fishes, sea turtles, seabirds, polar bears, seals, and sirenians (dugongs and manatees), to 23 threats that originate from human activities. These threats were classified into four categories, including climate change, coastal impacts, fishing, and maritime disturbances, with major threats within these identified as temperature extremes, drifting longlines, and fixed fishing gear.

The study examined the severity (intensity of impact), scope (extent of exposure), and timing of expected impacts (present or in the future), using these to assign each threat an overall vulnerability score that builds on the existing extinction risk classification system underpinning the International Union for Conservation of Nature Red List.

The authors found that some threats such as fishing gear present a high severity, meaning they can cause steep population declines,, while others, such as climate change and plastic pollution, have a larger scope, meaning they can affect many populations of marine megafauna but may not always be directly associated with declining populations.

According to the results, about 40 per cent of species are highly vulnerable to at least one threat. Turtles and sirenians were vulnerable to at least one threat across each of the four threat categories while sharks and rays were especially impacted by fishing-related threats. In addition, temperature extremes and plastic pollution affected the largest proportion of species.

The study highlights the need for coordinated, multi-pronged conservation strategies to reduce the risk of global extinctions of marine megafauna species across the world's oceans.

Figure. (a) Average vulnerability scores per taxa for each threat considered in each category and (b) average certainty of expert timing, scope, and severity scores across all species per taxa for each threat (solid circles, threat with the highest overall average vulnerability or certainty; open circles, highest value per category for categories where no threat is among the highest overall; multiple solid circles for average vulnerability, more than one threat had vulnerability scores with overlapping confidence intervals with the threat that had the highest average vulnerability; gray squares, no species were rated as having vulnerability to that threat in that taxa; silhouettes [left to right], bony fishes, cetaceans, elasmobranchs, flying birds, polar bear, penguins, pinnipeds, sirenians, turtles; all, all species considered).

Further details can be found here:

VanCompernolle et al. (2025). Vulnerability of marine megafauna to global at-sea anthropogenic threats. Conservation Biology, e70147. https://doi.org/10.1111/1365-2656.70145