Bycatch, major consequences
Last month, the press released a new assessment of the conservation status of sharks. We learned that 17 of the 58 species studied are now classified at risk of extinction by the IUCN (International Union for the Conservation of Nature). An alarming, yet « not surprising » figure for Nicholas Duvy, co-chair of the IUCN Shark Specialist Group and Canada Research Chair tier II in Marine Biodiversity and Conservation at Simon Fraser University. In particular, overfishing, which is preventing sharks with slow growth to reach sexual maturity. But also the bycatch and ghosts fishing. A problem resulting in the decline of populations and which offers no economic benefit. The flesh of the species caught is also not consumed since most of these bycatch are often discarded, dead or dying.
Too many bycatch
This term « bycatch » refers to the capture of non-target species. A problem largely due to the lack of selectivity of modern fishing methods. Among them, many turtles, dolphins … and also sharks. According to the Food and Agriculture Organization (FAO), bycatch may account for 1/3 of the global catch. In other words, the estimate ranges from 17.9 million to 39.5 million, averaging 27 million tonnes out of 94 million tonnes of fish caught per year. The constraint of census of these catches, applied to the tuna boats, allowed the scientists to have a more precise idea since about ten years. Another problem is the ghost fishing. Which is the fact that fishes are trapped by objects abandoned or thrown into the sea, by accident or not (ropes, pieces of nets, traps, traps of breeding …). They become, after their first use, deadly objects. To give a concrete example, let’s take the trawl. The most used fishing method in the world. There are 3 types: the pelagic trawl, for fish in open water; the bottom trawl, targeting species evolving, as the name suggests, close to bottom; and the beam trawl. The latter targets flatfish, shrimps … (new methods are being tested to reduce its impact). According to IFREMER (French Institute for Research into the Exploitation of the Sea), the first type announced above entails an accidental capture of cetaceans (studies are underway to develop acoustic or mechanical devices to reduce catches). The second, it causes a lack of selectivity in the species caught (not to mention the deterioration of habitats and organisms placed on the bottom). Finally, the latter has a very strong impact on the seabed because of its weight and the network of channels. It is also weakly selective, especially with regard to juveniles.
As stated earlier, some studies are underway to try to limit the significant and problematic impact of these catches. Organizations also offer solutions and guides for professionals, also visible as tools of understanding by the general public. For example, the WWF (World Wildlife Fund), worked on the implementation of a TED (Turtle Excluder Device) net on tropical shrimp trawlers, with the CRPEM (Regional Committee) Maritime Fisheries and Marine Farms) of French Guiana. This device is composed of a grid installed in the narrow part of a trawl which allows to release sea turtles (as well as other large marine species and objects), by an exit hatch while retaining and improving the quality shrimp caught. The effectiveness has been proven. As can be read on the WWF website, a trawl with a properly used TED avoids catching nearly 97% of marine turtles in the tropical shrimp fishery. In 2019, FAO published a « Guide for the Reduction of Bycatch in Trawl Fishing for Tropical Shrimp ». The latter is available for reading online. It includes the « types of sharks and rays encountered » by fishermen. All are on the IUCN Red List: the Whale Shark (Rhincodon typus); the Giant Manta Ray (Manta birostris); the Sea Devil (Mobula mobular); Scalloped Hammerhead shark (Sphyrna lewini), Silky Shark (Carcharhinus falciformis), Oceanic whitetip shark (Carcharhinus longimanus), and Mako shark or Shortfin mako shark (Isurus oxyrinchus).
Legal measures necessary for the protection of species
The Convention on the International Trade of Endangered Species (Convention on International Trade in Endangered Species of Wild Fauna and Flora), or the Washington Convention, entered into force on 1 July 1975. The latter is an intergovernmental agreement ensuring that international trade in specimens of wild animals and plants does not threaten the survival of the species to which they belong. Thus, CITES controls and regulates the international trade of these specimens, listed in its Appendices according to the degree of protection required. They are three in number. The first concerns species threatened with extinction. International trade is therefore prohibited unless the importation is not for commercial purposes. For example, this is allowed if the goal is scientific. In this situation, on an exceptional basis, the transactions take place on the condition that they are authorized by the issuance of an import and export permit (or a re-export certificate). The second concerns species that are not necessarily currently threatened with extinction but that could become so if the trade was not controlled. In this one are includes « look-alike species ». In other words, those whose commercialized specimens resemble those of species listed for conservative purposes. International trade in Appendix-II registrations may be authorized and must be covered by an export permit or a re-export certificate. Authorities issuing these permits should do so only if the established conditions are met and if they are satisfied that this will not affect the survival of the species in the wild. Appendix-III covers species already listed at the request of a Party that already regulates trade and needs the cooperation of other Parties to prevent its illegal or unsustainable exploitation. International trade in specimens of listed species is permitted only on presentation of previously issued permits or certificates.
Proposal to amend the mako shark (Isurus oxynchirus) and the small porbeagle shark (Isurus paucus) at COP18
The International Conference Center of the Bandaranaike Memorial in Colombo (capital of Sri Lanka) will host the CITES COP18. The 183 Parties (182 countries plus the European Union) will respond. An eighteenth session that could become the most important in the history of CITES. The number of items on the agenda has increased by 20%. Indeed, no less than 57 nominations (a record) and 107 working papers will be presented. Among the proposals this year are the trade in shortfin mako shark or mako shark (Isurus oxyrinchus) species and the small porbeagle shark (Isurus paucus). Indeed, this amendment includes the small porbeagle shark because, as specified in the eligibility criteria: « Specimens of the species are marketed in a form that makes them similar to specimens of a species listed in the Appendix-II ». This proposal is absolutely necessary and major in the Atlantic and the Mediterranean. Thus, protection measures for sharks and rays in specific Regional Fisheries Management Organizations (RFMOs) would progress. This species meets the listing criteria of Appendix-II because international meat and fin trade is an important driver of unsustainable and largely uncontrolled fisheries. The latter caused a decline in populations in all the oceans of the world. And the numbers are cold: the porbeagle population has been depleted around the world with a 60% decline in the Atlantic over 75 years.