Sea creatures are more likely to become extinct the bigger they are. A new report, published in Science, highlights that the extinction pattern in the world’s oceans has switched from being either non-selective or only selective for small-sized species to a scenario where the bigger a species is, the higher the risk of becoming extinct. Not surprisingly, the authors believe that the underlying cause is human action.
Using a database of 2,497 extinct and living marine vertebrates and mollusc species, the report’s authors compared the traits of extinct animals with those of species currently under threat of extinction. The results reveal a strong association of body size to the probability of being threatened by extinction. In the words of Jonathan Payne, leading author of the study:
What our analysis shows is that for every factor of 10 increase in body mass, the odds of being threatened by extinction go up by a factor of 13 or so. The bigger you are, the more likely you are to be facing extinction.
The association applies to both molluscs and vertebrates, and it’s robust enough to hold a wide range of different data treatments, including variation in the threat level used to distinguish threatened and non-threatened species.
The numbers also indicate that the association is rather recent. During previous mass extinctions, body size was either not related to extinction patterns or small animals were at a higher risk. So what has changed?
Although the causes were not explicitly examined, the authors point to the role of human action as the most likely explanation for their observations. According to co-author Noel Heim:
We see this over and over again. Humans enter into a new ecosystem, and the largest animals are killed off first. Marine systems have been spared up to now, because until relatively recently, humans were restricted to coastal areas and didn’t have the technology to fish in the deep ocean on an industrial scale
Read on...Support us and go ad-free
Climate change does not seem to play an important role as a driver of extinction in the marine ecosystem. Instead, similar to what is happening to large land animals, human actions are more likely to blame.
Since large animals are usually found at the top of the food web, their loss can have dramatic consequences for the rest of the species in their ecosystems.
To prevent this, the authors call for new regulations to manage ocean resources like fisheries. They believe that we still have time to tackle the threat if we act fast. Unlike other worrying trends, such as ocean warming and acidification, fish populations have the potential to recover relatively fast. Payne says:
We can turn this situation around relatively quickly with appropriate management decisions at the national and international level.
Policymakers should take good note. Protecting these large species might be crucial to preserve the richness of our marine wildlife. We must take action while we can. We may not have a second chance.
Featured image by Ignacio Amigo for The Canary
We need your help to keep speaking the truth
Every story that you have come to us with; each injustice you have asked us to investigate; every campaign we have fought; each of your unheard voices we amplified; we do this for you. We are making a difference on your behalf.
Our fight is your fight. You’ve supported our collective struggle every time you gave us a like; and every time you shared our work across social media. Now we need you to support us with a monthly donation.
We have published nearly 2,000 articles and over 50 films in 2021. And we want to do this and more in 2022 but we don’t have enough money to go on at this pace. So, if you value our work and want us to continue then please join us and be part of The Canary family.
In return, you get:
* Advert free reading experience
* Quarterly group video call with the Editor-in-Chief
* Behind the scenes monthly e-newsletter
* 20% discount in our shop
Almost all of our spending goes to the people who make The Canary’s content. So your contribution directly supports our writers and enables us to continue to do what we do: speaking truth, powered by you. We have weathered many attempts to shut us down and silence our vital opposition to an increasingly fascist government and right-wing mainstream media.
With your help we can continue:
* Holding political and state power to account
* Advocating for the people the system marginalises
* Being a media outlet that upholds the highest standards
* Campaigning on the issues others won’t
* Putting your lives central to everything we do
We are a drop of truth in an ocean of deceit. But we can’t do this without your support. So please, can you help us continue the fight?