Modern methods of fishing are pushing some species of whales and dolphins towards extinction
Almost a dozen species of small cetaceans are on the road towards extinction. An international group of scientists, including Morigenos, reviewed the current status of small cetaceans globally. The main reason for the worrisome status of most of them are the fishing nets that catch and kill hundreds of thousands of marine mammals each year.
Whales and dolphins lived alongside human fishers in coastal seas and rivers for thousands of years. But after World War II, the nets made of cotton and hemp were replaced by cheaper and more durable synthetic nets. These gill-nets do not require large boats or expensive equipment, which makes them very attractive to small-scale coastal fishermen worldwide. But this durability also makes these nets a deadly trap for many species of whales, dolphins, other marine mammals and sea turtles, which often do not notice them and cannot escape from them once caught.
For the past 30 years, researchers and conservationists have been trying to develop nets that the animals could successfully avoid or break out of, but so far a good solution has not been found. They also called upon governments of several countries to adopt stricter measures on the use of such nets, but these measures are difficult to implement in practice, especially in third world countries. Unfortunately, things are not simple, since millions of people worldwide depend on small-scale coastal fishing, especially in poorer countries.
Of course, fishing is not the only or main threat to all species of whales and dolphins globally. Issues are very species-, country-, and area-specific. But generally speaking, gill-nets are the main threat to marine mammals globally, particularly in Africa, Asia and South America, although Europe is not exempt.
The new review study reports that 11 species of small cetaceans are dangerously close to extinction. The study, which also involved Tilen Genov from Morigenos, was published in the international scientific journal Endangered Species Research. The scientists reviewed information on population sizes, trends and bycatch levels globally. The river dolphin baiji in China is almost certainly extinct. The vaquita, a species of porpoise found only in the upper Gulf of California in Mexico, currently numbers fewer than 19 animals and is literally on the brink of extinction. The long-term prospects for the Atlantic humpback dolphins, found along West Africa, are rather grim. The outlook is also rather poor for the Māui dolphin, found only off New Zealand, as well as for the Taiwanese humpback dolphin, the Yangtze finless porpoise, three species of Asian river dolphins, and the Baltic Sea harbour porpoise. In all these cases, gillnets are the biggest threat.
“Many of these species will vanish unless gillnets are eliminated”, said Robin Baird, a cetacean expert at Cascadia Research Collective, USA, who was not involved in the study. But that will take “political courage,” he stressed, because governments will have to make unpopular decisions, such as enacting no-fishing conservation zones and enforcing strict bans. Unfortunately, he said, at this point that is the only way “to keep these species and populations from going extinct.”
Tilen Genov from Morigenos said: “Slovenia, fortunately, isn’t part of this statistic. Bycatch of dolphins in fishing nets does occur here, but appears relatively rare. When it does happen, the fishermen typically contact us themselves. We have a very good collaboration with them. We also currently have no indication of any dolphin population decline.” He added: “Of course, as researchers we do not only care about dolphins, as we are well aware that the right solutions need to be good for people and endangered species alike. But this will take a lot of effort, collaboration and innovation.”
The study is freely available at the following link: https://www.int-res.com/abstracts/esr/v40/p285-296/