Extinction of Chondrichthyes

 The extinction of species is most often brought up when discussing climate change and the state of our environment. Human activity has caused so many extinctions that we are now in the world’s sixth mass extinction. The extinction of species can be caused by a variety of factors and can occur in many different places. However, this post focuses on the extinction of chondrichthyes in the world’s oceans. 

The abundance of many different chondrichthyes are not well documented, so many more chondrichthyes could be threatened without our knowledge. The class chondrichthyes includes sharks, rays, and chimeras. The knowledge on the extinction rate of many species in this class is data deficient which means that there is not enough information to determine the true status of these animals. 

There are regulations on how much these animals can be fished, and protections have been put in place. Still though, these different protections are very limited and varied. This study looked at 1,199 different species of chondrichthyes from 2013-2021; however, the knowledge of the extinction rate of many of these species observed in the study are data deficient. This data deficiency is not only harmful for scientific purposes, but it also makes it hard to ignite a sense of urgency in protecting these species. Correct information is necessary to implement relevant protections on chondrichthyes. 

Currently, one third of chondrichthyes are threatened globally. This number of threatened species of chondrichthyes has doubled since 2014. However, this jump in threatened species could be because there are now more accurate systems of taking data rather than the number of endangered species actually having doubled. Now, scientists need to discover how much of a change there actually has been in the number of threatened species to better be able to accurately determine the probability of an extinction. 

Extinctions are mostly because of overfishing, but they can also be caused by climate change, habitat loss, and pollution. While chondrichthyes are not always directly fished for, industrial fisheries often take up chondrichthyes as bycatch. Sustainable fishing practices can help with reducing bycatch, something that could drastically help threatened chondrichthyes recover. 

Species at shallower depths are more likely to be threatened than deepwater fish as they are easier to catch. However, deep water fisheries are expanding, increasing the chance of deepwater fish being caught as bycatch. There has also been significant biodiversity loss in the tropical coastal seas as fish are more likely to be threatened in the tropics and subtropics. The greatest threat is to fish living in coastal shelf waters. 

 The best way to prevent extinction is through protection programs and the spread of information on our oceans and their chondrichthyes. Species management will not only allow for continued fishing to sustain the economy, but it will also allow for the survival of more species and increased biodiversity. 

Currently, there is a high risk of extinction for chondrichthyes because of ineffective and minimal management. Reducing catch to sustainable levels and avoiding endangered species will allow for our oceans to maintain their biodiversity and many complex ecological systems.

Nicholas K. Dulvy, Nathan Pacoureau, Cassandra L.. Rigby, et al. “Overfishing Drives Over One-third of All Sharks and Rays Toward a Global

    Extinction Crisis.” Science Direct, vol. 31, Issue 21, 2021, pp. 4773-4787

Sharks:

“Snorkeler Suffers 'Suspected Shark Bite'.” BBC News, BBC, 2 Aug. 2022,  https://www.bbc.com/news/uk-england-cornwall-62400251.

Chimera:

Crampton, Linda. “Chimaera Facts: Strange Fish with a Cartilaginous Skeleton.” Owlcation, Owlcation, 23 Nov. 2012,

    https://owlcation.com/stem/The-Chimaera-Ratfish-or-Ghost-Shark-Strange-and-Cartilaginous.

Ray:

“Bat Ray.” Wikipedia, Wikimedia Foundation, 21 Oct. 2022, https://en.wikipedia.org/wiki/Bat_ray.