No matter how deadly and powerful they seem. Neither does his lineage go back millions of years. The great white shark, the hammerhead fish or the oceanic shark cannot counter human commercial pressure: uncontrolled fishing has put half of the oceanic shark species in danger of extinction. Its global abundance in open waters has fallen by 71% since 1970, according to a scientific analysis just published in Nature.
The collapse of these sharks and also of the pelagic rays coincides with the accelerated increase in fishing pressure. The researchers recall that commercial catches of these varieties have tripled in half a century, which means that three quarters of the 31 species of both families, that is, 24 varieties, have fallen into the category of “endangered” of the International Union for Conservation of Nature (IUCN).
“Oceanic rays and sharks are at exceptionally high risk of extinction, much greater than, say, a species of bird, mammal or frog,” explains Nicholas Dulvy, professor at Simon Phrase University.r from Canada, one of the institutions that make up the Global Shark Trends Project, responsible for the study.
Overfishing of these animals has followed a clear pattern of “serial depletion”. The first to fall have been the largest sharks that were already in a bad situation by 1980. Then came the decline in the populations of medium-sized species and now it has spread to the smallest. “All oceanic shark and ray species except one have seen their level of abundance decimated” throughout this time, states this work.
The market is thinning. Especially from 1990 onwards, the fishing industry soared its catches to satisfy the demand for fins, oil, meat and gill rakers. The data are very clear since, if in 1980 “there were only nine species in danger” and two thirds were in an acceptable state, currently the tables have been turned and three out of every four varieties are officially threatened.
The European Union fleet of vessels alone catches 56,000 tonnes of sharks and rays in the North Atlantic. “One of the main problems is that it is very difficult to take protection measures for sharks without affecting the catches of other species,” they admit to the European Commission. In the central and southern part of the ocean, most catches occur when looking for other species, explains the EC. All in all, this “accessory” fishing amounts to some 31,000 tons in those latitudes. Fishing for oceanic sharks is prohibited in the southeast Atlantic.
Spain, as the leading European fishing power, is not immune to this circumstance. Last fall, the Ministry of Ecological Transition stopped the sale of about 600 tons of porbeagle, considering that the quota of catches initially admitted by the Ministry of Agriculture and Fisheries in the North Atlantic (just over 900 tons) exceeded the international marketing limit of this species –which is threatened– decreed by Industry and Commerce at 350 tons. A discrepancy that the employers’ association Cepesca considers could lead to the “collapse of the longline fleet.” Meanwhile, the porbeagle (Isurus oxyrinchus) it is still anchored in the classification of “in danger of extinction”.
The problem with sharks and rays is that, as they are usually slow growing and few young, they are very susceptible to overfishing. In fact, scientists have evaluated up to 11 different types of threats, including “human disturbances” and adverse weather events. However, above all, the “fishing and capture of biological resources” is repeated.
In addition to the case of the iconic white shark – which has precisely slowed its path to disappearance since its capture was prohibited in some marine areas – some sharks that were abundant in almost all marine latitudes have experienced such a “dizzying reduction” that are currently in danger.
A great predator, crucial for the balance of ecosystems, like the ocean shark is in a “critical” state. Just like the hammerhead shark. The pelagic fox with its very long tail fin, the wolf shark, the aforementioned porbeagle or the black porbeagle are also advancing towards extinction. The list is very long.
The problem is that these animals do not have a very good image and their slide towards disappearance goes unnoticed despite the fact that they have an essential function for the sea to be a fishing ground for life (on which the economy and food of many populations depend). “Oceanic rays and sharks are vital to the health of vast marine ecosystems, but because they are hidden beneath the ocean’s surface, it has traditionally been difficult to assess and monitor the status of their populations,” admits Nathan Pacoureau, lead author. of this research.
By areas, if populations have stabilized in the Atlantic, always at low levels according to the study, after years of continuous decline, in the Pacific a drop in abundance of 67% has been calculated and even worse in the Indian Ocean where the collapse it is “steep and continuous” as the decline reaches 84%.