Updated: Jul 26
In recent years scientists have been becoming increasingly aware that the global declines in shark populations are completely unsustainable... As a group, sharks are thought to have declined by 70%, with some species suffering as much as a 90% reduction in their population size! If we are to turn this around, it will be critical that the general public understand the threats to sharks and support conservation initiatives. If we all work together, we CAN ensure that governments hear our concerns for sharks and move towards protecting them! So on this International Shark Awareness day, take steps to raise your own awareness and that of those around, to the serious plight of sharks!
Habitat Degradation Affects Sharks
Sharks have declined globally due to multiple threats from humans. Shark habitats have been completely decimated by humans dredging the ocean bottom for fishing, or to alter coastal geography for shipping routes or urbanisation. But their habitats can also be more insidiously degraded. Pollution - both litter and chemical pollutants - often find their way into the ocean and can poison or injure sharks, especially those living near to highly urbanised areas. Microplastics have been found to build up in shark tissues and lead to mortality and larger pieces of trash can wrap around sharks, causing serious injury or death. To learn more check out The Worst... Beware of the Plastics!. Sharks are also vulnerable to "ghost fishing"; when they are indiscriminately killed by fishing gear that has been lost or abandoned at sea. See Ghosts in the Ocean for more info. Habitats are also changed increasingly with climate change; the area covered by coral reef is decreasing, and waters are warming and becoming more acidic (Worm et al, 2013).
Sharks are Overfished
Yet, by far the greatest threat to sharks is their extraction in fisheries. Sharks have been specifically targeted by fisheries since the 1960s, as their meat, fins and oil were very valuable, and since the 1980s these fisheries have hugely expanded. It is estimated that millions of tonnes of sharks are "landed" (fished and brought into port) every year, but generally shark fisheries are very poorly regulated and it is thought that millions more tonnes are unreported or landed illegally. Sharks are sometimes finned at sea and their bodies discarded, which can skew landing figures and many small-scale or substance fisheries (aka "artisanal fisheries") do not report their landings at all. Whatsmroe, many sharks are killed as "bycatch" in fisheries targeting other commercially valuable species. To learn more, see A Fish Out of Water (Worm et al, 2013).
The United Nations Food and Agricultural Organization (FAO) reports that at least 63 million sharks have been landed annually since 2000 and it is often suggested that if we included illegal catches and unreported landings, it is more likely around 100 million sharks are killed in fisheries each year. However, a recent study (Worm et al, 2013), considering unreported landings and catches of sharks in artisanal fisheries, found that this figure is far too conservative and that it is likely that mortality is up to 273 million sharks every year!
"[Global shark mortality] estimated to range from 63 to 273 million sharks [annually]"
- Worm et al, 2013
The major concern for shark conservationists is their very poor ability to recover once their populations have declined. Unlike boney fishes, sharks are described as having "K-selected life history strategy"; long life-spans and a late age of maturity and thus, low "fecundity" (aka fertility) mean they have relatively few offspring over the course of their lives and the growth of their populations is incredibly slow. It is estimated that shark populations could take decades to recover to a healthy level even if their extraction was reduced to zero! (Worm et al, 2013)
A Team Effort
The FAO and other bodies launched the International Plan of Action for Sharks in 1999 (IPOA-Sharks), in order to manage shark fisheries and improve conservation of threatened species. The International Union for the Conservation of Nature (IUCN) also launched a specialist group for sharks. Many shark species are categorised as Endangered' by the IUCN and therefore, their international trade has been limited by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
But many different measures must be administered in cohort in order to bolster shark populations and these strategies must be implemented internationally. Catch limits must be set for especially threatened sharks, including localised spatial / temporal fisheries closures if populations are decimated in certain locations. Landings must be accurately reported and strictly limited based upon scientific advice. Illegal fishing must be policed and punishable by law, and illegal import / export of shark products must be more efficiently controlled. It will also be important to protect critical areas of habitat; creating shark sanctuaries and marine protected areas (MPAs), where shark fishing is completely banned.
I'm Worth It
Making all the nessary change will undoubtedly be very costly and involve an enormous amount of work, but we can achieve these goals if there is enough public pressure to drive government action. Therefore, that is why I believe that whilst all the aforementioned measures will be vital, in my opinion, the most important measure is improving education. It is vital that everybody understands the realty of shark declines and actively supports shark conservation. In several countries, public pressure has directly lead to finning bans! If we all come together and demand the protection of sharks, we can have a very real impact!
So share this blog with your friends, especially those who maybe don't understand or care about shark declines, and tell everyone you know why they should feel passionately about conservation!
You can get directly involved by:
Educating your children about sharks through Sharks4Kids or by encouraging them to watch nature documentaries.
Writing to your government to express your concern. Google who your representative is for environmental affairs or fisheries and write them a sternly worded letter! This might sound like such a small thing, but if every single one of us did this, they would have to listen!
Worm B, Davis B, Kettemer L, Ward-Paige CA, Chapman D, Heithaus MR, Kessel ST & Gruber SH (2013). Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy, 40, 194–204. Access online.