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Are Sharks Endangered & If So, Why?

Reading Time: 5 minutes

By Dr. Leonardo Guida, Australian Marine Conservation Society

 

Sharks have been on this earth for around 450 million years, that’s before the first tree ever sprouted from a seed (Xu et al. 2017)! They’ve survived five mass extinction events however the question we now ask ourselves is, will they survive Us? 

 

Sharks, rays and chimaeras are all cartilaginous (cartilage, the stuff your nose is made of!) fish, making them part of the same group of animals called ‘chondrichthyans’, but for simplicity we’ll refer to them here as ‘sharks’. This group of animals is the most endangered of all marine life. Consisting of around 1200 species, more than one third (37%) are threatened with extinction. In the last 50 years, numbers of oceanic sharks and rays have plummeted by 70% (Pacoureau et al. 2021).

 

Overfishing is the single biggest driver of extinction risk for sharks. Generally, sharks mature at 10 years old and produce 4-6 young every two years (Heupel et al. 2019). Put simply, we’re fishing them faster than they can replace themselves.

 

Are sharks endangered in Australia?

 

The short answer is ‘yes’. Australia is a shark biodiversity hotspot, with one quarter of the world’s species (328) calling our waters home. From a global perspective, Australia’s sharks are in a relatively good spot thanks to our geographic isolation, and relatively well-resourced and managed fisheries. However, 39 species in Australian waters are threatened with extinction, and a third (36%) of those species are endemic – that is, they’re not found anywhere else in the world but here (Kyne et al. 2021). Zooming in closer, we see there are significant problems in our own backyard.

 

What threats do sharks face in Australia?

 

Australia imports and exports shark fin, meat and other products like cartilage and oil (squalene)  for use in medicinal and cosmetic products. You may be shocked to learn that there are endangered sharks which are legally caught in Australian waters and traded for these products because of weak laws or a lack thereof. Endangered school (Galeorhinus galeus) and scalloped hammerhead (Sphyrna lewini) sharks (Kyne et al. 2021)are legally caught and traded for meat and fins because of a loophole in Australia’s national environmental laws, the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The category “Conservation Dependent” (CD) in the EPBC Act allows fish that would otherwise be ‘Endangered’ under the same law, to killed for sale, seemingly prioritising economic considerations over environmental. 

 

Some of the most endangered shark species are the endemic ‘Aussie’ species. For example, the Critically Endangered whitefin swellshark (Cephaloscyllium albipinnum) and Critically Endangered Australian longnose skate (Dentiraja confusa) (Kyne et al. 2021) are still legally fished for their meat at respective minimum averages of 1,390 and 1,820 individuals each year (Daley and Gray 2020) and there are no rules in place to to protect them. In eight years, the extinction risk of the whitefin swellshark jumped three categories from Near Threatened to Critically Endangered (Daley and Gray 2020).

 

Some of our most iconic, world-famous species are fully protected by law in Australia under the EPBC Act, meaning they can’t be fished. However, that doesn’t mean they’re out of the woods and recovering these endangered shark species requires ongoing monitoring of the populations and improving their on-water protection accordingly. Let’s take a quick look at some!

 

Why are whale sharks endangered?

 

Whale sharks (Rhincodon typus) are considered one global population and are Endangered due to fishing pressure (historical and current), although this now predominantly occurs outside of Australian waters (Kyne et al. 2021). Marine sanctuaries, and international laws have slowed their decline and in Australia, whale sharks are listed as Endangered on the EPBC Act. New research shows that more than 90% of the migratory paths of whale sharks overlap with major shipping routes and because they like swimming at the surface, ship-strikes could be playing a significant part in their ongoing global decline (Womersley et al. 2022). Whale sharks are a frequent visitor to the famous Ningaloo Reef in Western Australia, however nearby industrial ports and proposed expansions of ports and shipping activity place whale sharks at greater risk.

 

Why are great white sharks endangered?

 

Globally and in Australian waters, great white sharks (Carcharodon carcharias) are Vulnerable, one step away from Endangered (Kyne et al. 2021). Commercial fishing and targeted trophy fishing (for their jaws) in Australia were the primary drivers of their declines and the species has been nationally protected under the EPBC Act since 1999. Fortunately its protection now means their numbers in Australia have only recently stabilised from historical declines, with a current estimated population of ~2200 adults (Kyne et al. 2021). However, the species is still one of 19 target species which can legally be killed as part of Queensland’s Shark Control Program.

 

Why are grey nurse sharks endangered?

 

Grey nurse sharks (Carcharias taurus) consist of two populations in Australia, with the east coast population being Critically Endangered and the west coast population being Vulnerable (Kyne et al. 2021). On the east coast, there are estimated to be only around 2200 adults, having experienced dramatic declines and disappearance from some aggregation sites because of targeting by spear fishers in the 1960s and 1970s, as well as accidental capture in fisheries, and the shark control programs of New South Wales and Queensland (Kyne et al. 2021). Grey nurse sharks are super slow breeders, giving birth every second year to just two pups at a time (Kyne et al. 2021). Thanks to creation of marine sanctuaries around their aggregation sites and bans on targeting the shark, it is believed they may be recovering although it is yet to be quantified (Kyne et al. 2021). Unfortunately significant challenges still exist include the recent rolling back of protections of critical habitat at Montague Island in NSW and the impacts of climate change affecting their distribution and habitat.

 

How can we stop the decline and help sharks recover?

 

You’ve already made the first step, and that is by reading this article and becoming informed. Second step is to join us and over 70,000 people and become a Shark Champion, taking action to create environmentally sustainable fisheries and stopping shark culling in Australian waters once and for all. Healthy oceans need sharks. We are their biggest threat, but we’re also their only hope.

 

References

 

Daley R, Gray C (2020) ‘On-the-water management solutions to halt the decline and support the recovery of Australia’s endemic elasmobranchs.’ (WildFish Research Consultancy & Horizon Consultancy. Self published: Australia)

Heupel MR, Kyne PM, White WT, Simpfendorfer CA (2019) Shark Action Plan Policy Report. report NESP Marine Biodiversity Hub, Available at http://epubs.aims.gov.au//handle/11068/15377 [Verified 18 August 2020]

Kyne PM, Heupel MR, White WT, Simpfendorfer CA (2021) The Action Plan for Australian Sharks and Rays 2021. report NESP Marine Biodiversity Hub, Hobart.

Pacoureau N, Rigby CL, Kyne PM, Sherley RB, Winker H, Carlson JK, Fordham SV, Barreto R, Fernando D, Francis MP, Jabado RW, Herman KB, Liu K-M, Marshall AD, Pollom RA, Romanov EV, Simpfendorfer CA, Yin JS, Kindsvater HK, Dulvy NK (2021) ‘Half a century of global decline in oceanic sharks and rays’ Nature 589, 567–571. doi:10.1038/s41586-020-03173-9

Womersley FC, Humphries NE, Queiroz N, Vedor M, da Costa I, Furtado M, Tyminski JP, Abrantes K, Araujo G, Bach SS, Barnett A, Berumen ML, Bessudo Lion S, Braun CD, Clingham E, Cochran JEM, de la Parra R, Diamant S, Dove ADM, Dudgeon CL, Erdmann MV, Espinoza E, Fitzpatrick R, Cano JG, Green JR, Guzman HM, Hardenstine R, Hasan A, Hazin FHV, Hearn AR, Hueter RE, Jaidah MY, Labaja J, Ladino F, Macena BCL, Morris JJ, Norman BM, Peñaherrera-Palma C, Pierce SJ, Quintero LM, Ramírez-Macías D, Reynolds SD, Richardson AJ, Robinson DP, Rohner CA, Rowat DRL, Sheaves M, Shivji MS, Sianipar AB, Skomal GB, Soler G, Syakurachman I, Thorrold SR, Webb DH, Wetherbee BM, White TD, Clavelle T, Kroodsma DA, Thums M, Ferreira LC, Meekan MG, Arrowsmith LM, Lester EK, Meyers MM, Peel LR, Sequeira AMM, Eguíluz VM, Duarte CM, Sims DW (2022) ‘Global collision-risk hotspots of marine traffic and the world’s largest fish, the whale shark’ Proceedings of the National Academy of Sciences 119, e2117440119. doi:10.1073/pnas.2117440119

Xu H-H, Berry CM, Stein WE, Wang Y, Tang P, Fu Q (2017) ‘Unique growth strategy in the Earth’s first trees revealed in silicified fossil trunks from China’ Proceedings of the National Academy of Sciences 114, 12009–12014. doi:10.1073/pnas.1708241114

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