"The shark fin trade is notoriously secretive. But we were able tap into fin auction records and convert from fin sizes and weights to whole shark equivalents to get a good handle on the actual numbers," says lead author Shelley Clarke, Ph.D, an American fisheries scientist based in Hong Kong and Japan.
A team of researchers calculated the number of sharks represented in the fin trade using a unique statistical model and data from Hong Kong traders. When the figures were converted to shark weight, the total is three to four times higher than shark catch figures reported to the United Nations Food and Agricultural Organization (FAO).
"Without any real data, numbers as high as 100 million had been floating around for a while, but we had no way of knowing whether or not this was accurate," says Ellen Pikitch, Ph.D., co-author and executive director of the University of Miami's Pew Institute for Ocean Science. "This paper, which produces the first estimate based on real data, shows that the actual number of sharks killed is indeed very high but is more likely to be in the order of tens of millions, with a median estimate of 38 million sharks killed annually."
Concern about the shark finning trade has grown over the past few years as demand has surged beyond sustainable levels for slow-to-produce shark populations and without regulation in most countries. Three shark species are listed on the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES), and 20 percent are threatened with extinction according to the 2006 Red List of Threatened Species.
Used in shark fin soup, a delicacy served at Chinese weddings and other celebrations for centuries and more recently at business dinners in Southeast Asia and the Pacific Rim, fins are the most valuable part of the shark, which typically are sliced off as the shark, sometimes still alive, is thrown back into the ocean. The shark fin trade appears to be keeping pace with the growing demand for seafood--up five percent per year in mainland China. Determining whether shark populations can continue to withstand the magnitude of catches estimated by Clarke and her team depends upon the size and status of each population.
"One of the most productive sharks is the blue shark, and it appears that the catch rate is near the maximum sustainable level," says Clarke. "But such assessments were not available for other, less productive shark species. It is quite likely that sustainable catch levels have already been exceeded in some cases."
The United Nations FAO compiles catch records for sharks and other fish, based on information submitted from member countries. Where possible, the FAO attempts to verify the accuracy of the figures, but verification often is not practical. Many sharks may be recorded as unidentified fish and thus not be recognizable as sharks in the FAO records.
"Due to the low value of shark meat in many markets, shark fins may be the only part of the shark retained, and often these fins are not recorded in the catch log or when landed at ports. I knew we had to somehow access the major markets if we were to accurately estimate the number of sharks killed," says Pikitch, who initiated the project.
International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
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24.03.2017 | Physics and Astronomy