The life history traits of most shark species, including late maturity, slow growth rate low fecundity ( few offspring) make them particularly vulnerable to overfishing. A global analysis done in 2021, found that 32 % of the 1,199 species of shark, ray and chimaera that were assessed were critically endangered, endangered or vulnerable.
Listed below are the reasons why sharks are disappearing at an alarming rate.
Shark finning is the removal and retention of sharks while at sea. Once the fins have been removed the carcass (body) is thrown back into the ocean. Without fins, the sharks are unable to swim and pass water over its gills, which results in the death either from suffocation or predation by other animals. Shark fins are used in shark fin soup, a traditional Asian dish. This soup is among one of the most valuable fishery products in the world, with fins selling for more than $100 US/kg. This lucrative business has led to an estimated 26 million to 73 million sharks being killed every year to support this trade. Sometimes there is confusion regarding sharks fins and shark finning. Shark fins on the market did not necessarily come from finning, but they could have. Here are some definitions to help understand this issue.
Shark Finning: Removal and retention of shark fins and the discarding at sea of the carcass.
Shark Fin Trade: The global import and export of shark fins.
Shark Finning Ban: The act of shark finning is illegal in a region or country's surrounding waters.
Shark Fin Ban: Can include a ban on the sale, import, export and/or possession of shark fins.
Fins Attached: Means the entire shark must be landed and brought in to port.
Fishing is the most impactful practice for sharks and rays, mainly motivated by high consumption demand and technological development, which favors greater fishing effort and uncontrolled activity, resulting in overfishing and imminent collapse of populations. Although people have caught and consumed sharks for many hundreds of years, only in recent decades the demand for shark products has increased exponentially, creating a truly global market.
Today, industrial and artisanal fleets from all over the world supply traditional Asian markets for shark fins, including skate and ray fins. In addition, the shark meat trade is increasingly being diverted along separate supply channels to meet demand in growing markets such as Brazil and Mexico. This because a combination of demand growth and antifinning regulations intended to encourage the full utilization of carcasses has seen the market for shark meat expand considerably.
Sharks are caught as target or bycatch by a variety of fishing vessels, from local artisanal boats to industrial longline fleets. Typically, artisanal sector (e.g. small longliners and net fisheries) use ice for preservation and supposedly catch juvenile and neonate sharks for domestic consumption, while industrial gillnets and longliners, which catch mature sharks and use a freezer system to preserve the product, usually export these sharks (fins and/or meat) to other countries.
Furthermore, in some regions recreational fishing can be even more impactful for some shark species. For example, from 2013-2015 more non-dogfish sharks were killed in the United States by recreational fishing than by commercial fishing State of U.S. Fisheries, 2013, 2014, 2015).
Bycatch is the unwanted fish and other marine creatures caught during commercial fishing for a different species ( non target species). Many species of shark are caught as bycatch.
Habitat Loss and Degradation
Habitat loss occurs when an area is changed or degraded to a point where it can no longer serve as a home for the species that live there.
This loss can come from direct and indirect actions. Human activities including trawling, mangrove removal, coastal development, mining, aquaculture, and pollution are causes of habitat loss.
The release of greenhouse gases into the atmosphere is affecting oceans in various ways including coastal erosion, weather patterns, frequency of storms ( hurricanes), water temperature and sea level. This in turn has an impact on marine life, including sharks. These changes can influence migration, food distribution, reproduction, behavior and even size at birth.
EPAULETTE SHARK studies have shown that increased temperatures have sped up their growth rates. Pups hatch from eggcases earlier and are exhausted. It also indicates the risk for other species to be born weaker and smaller.
Marine Debris & Pollution
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Dulvy et al. 2021. Overfishing drives over one third of all sharks and rays toward a global extinction crisis. Current Biology, 31(21), 4773-4787.
Hammerschlag, N., McDonnell, L. H., Rider, M. J., Street, G. M., Hazen, E. L., Natanson, L. J., McCandless, C. T., Boudreau, M. R., Gallagher, A. J., Pinsky, M. L., & Kirtman, B. (2022). Ocean warming alters the distributional range, migratory timing, and spatial protections of an apex predator, the tiger shark (Galeocerdo cuvier). Global Change Biology, 28, 1990– 2005. https://doi.org/10.1111/gcb.16045
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Parton, K.J., Godley, B.J., Santillo, D. et al. Investigating the presence of microplastics in demersal sharks of the North-East Atlantic. Sci Rep 10, 12204 (2020). https://doi.org/10.1038/s41598-020-68680-1
S. Niedermueller et al., “The shark and ray meat network: A deep dive into a global affair 2021” (World Wildlife Fund Mediterranean Marine Initiative, Rome, 2021).
Shiffman, D. S., Macdonald, C., Ganz, H. Y., & Hammerschlag, N. (2017). Fishing practices and representations of shark conservation issues among users of a land-based shark angling online forum. Fisheries Research, 196, 13-26.
Wheeler, C.R., Rummer, J.L., Bailey, B. et al. Future thermal regimes for epaulette sharks (Hemiscyllium ocellatum): growth and metabolic performance cease to be optimal. Sci Rep 11, 454 (2021). https://doi.org/10.1038/s41598-020-79953-0
How does habitat loss affect sharks and rays - https://saveourseas.com/worldofsharks/threats/habitat-loss