Scientists warn about the need to preserve sharks

Near 40 Biological Sciences professionals, specialists in different aspects of the biology of sharks and other fish, expressed their concern about irresponsible and illegal attitudes like those shown in a recently released video, in which recreational fishermen exhibit a catch of 8 specimens of “Escalandrún” (sand tiger shark), one of the most threatened species of the Argentine Sea.

Sand tiger shark (Carcharias Taurus). © Luis Lucifora

On January 11, a video showing what appear to be recreational fishermen in a rigid inflatable boat, with an illegal catch of 8 sharks of the species commonly known as sand tiger shark (Carcharias taurus) in waters off Mar Chiquita, province of Buenos Aires, was broadcasted by the media and in social media.

In principle, the catch shown in the video is illegal because it violates Articles No. 217/2007 and 78/2014 of Buenos Aires province. These regulations establish that captured sharks of the species sand tiger shark (Carcharias Taurus), Bacota (Carcharhinus brachyurus), Leopard (Notorynchus cepedianus), Hammerhead (Sphyrna zygaena) and Cazón (Galeorhinus galeus) have to be returned to the sea, limit the number of rods per fisherman and also stipulate how fishing rods should be assembled. In addition, resolution No. 04/2013 of the Federal Fisheries Council is still valid, and it establishes that commercial fishing vessels can not land sharks longer than 1.6 meters in any Argentinian port.

These regulations are intended to preserve and make sustainable use of large sharks populations of the Argentine Sea. They are based on scientific knowledge of the biology of these species in Argentine waters accumulated over many years, which indicate that these sharks have a very low reproductive rate and that their populations have suffered severe declines. The sand tiger shark, or “escalandrún”, is a shark of seasonal occurrence that moves between Argentina, Brazil and Uruguay, so it is affected by fishing activities in these three countries. Female sharks reach their reproductive age at 14-15. Once they reached the reproductive age, they give birth to two offspring, with a maximum frequency of once every two years. The coasts of Buenos Aires are very important in the life cycle of this species, since it is believed that they mate in these waters, and that is fundamental for the preservation of the species. The latest scientific analysis indicates that the abundance of this species has decreased drastically in Argentina. In fact, the population of this shark shared between Argentina, Brazil and Uruguay was listed as “Critically Endangered” by the International Union for the Conservation of Nature, which is the main international organization dedicated to the evaluation and preservation of biodiversity.

Sand tiger shark (Carcharias Taurus). © Luis Lucifora

The sand tiger shark is a harmless species of shark that feeds on medium-sized fish (mainly hake, sea bass, narrownose smooth-hound, rays) and its teeth are not adapted to cutting prey in pieces. For this reason, sharks usually swallow their prey in one piece and do not feed on prey bigger than the size of their mouth. The same applies to bait on fishing hooks. Consequently, the hook usually gets stuck in their internal organs (stomach, liver, esophagus, heart), causing serious injuries that question the survival of individuals returned to the water. To prevent these injuries, responsible shark fishermen follow the recommendations of the current regulations and place a medium buoy (about the size of a grapefruit) about 25-30 cm from the hook to stop sharks from swallowing the hook. This grants them more chances of survival when being released. It is also advisable to use circle hooks, which are more prone to hook onto the mouth, minimizing sharks’ internal damage.

The undersigned are Biological Sciences professionals who specialize in different aspects of the biology of sharks and other fish. We want to express our concern regarding the irresponsible and illegal acts such as those shown in the above mentioned video, which, unfortunately, continue to occur every summer. For all these reasons, we urge all fishermen to comply with the current regulations and we strongly recommend that they use capture techniques that minimize the negative impact on sharks. In addition, we ask the authorities to carry out the necessary controls to make sure regulations are obeyed. Finally, we ask all citizens to make responsible use of natural resources; the preservation of sharks, the marine ecosystem and, ultimately, of our own species, depend on the actions of each one of us.

SIGNERS

From the Forum for the Conservation of the Patagonian Sea we support the statement prepared by numerous specialists from the main academic institutions and organizations in our country, among them, Wildlife Conservation Society, Temaiken Foundation and Argentine Wildlife Foundation, members of the Forum. With the advice and participation of local scientists and experts from the member organizations of the Forum, from the Forum we developed workshops and regional discussion sessions to evaluate the conservation status of species from the Patagonian Sea, including sharks. The indicators generated are key to evaluating management and conservation actions tending to safeguard the natural capital of species in our region.