The fifteenth meeting of the Conference of the Parties to the United Nations Convention on Biological Diversity (COP15) officially opened in Kunming, Yunnan. The international community has high hopes for this conference, hoping that the conference will promote the construction of a post-2020 global biodiversity governance system and reverse the trend of accelerated loss of global biodiversity as soon as possible.

Among these, the issue of marine biodiversity has become an urgent topic.

↑Marine biologist Christopher Halley photographed mussels "cooked" by heat waves this summer on the coast of British Columbia, Canada.

In recent years, scientific research has continuously pointed out that climate change has seriously affected marine biodiversity on a global scale, and biological extinction began in the ocean; (Click here to read: 55 million years ago Mysterious high temperature event)

The 2021 Nobel Prize in Physics has been historically awarded to the field of atmospheric and oceanic sciences for the first time...

Recently, Red Star News talked with the World Conservation Union (IUCN) Nick Dulvey, co-chair of the IUCN Shark Expert Group, and many other marine biologists discussed the current status of marine life and the global efforts needed to protect marine biodiversity.

Overfishing and climate change are driving a large number of marine life to extinction

In January this year, Dulvey and Nathan Pacullo, a marine biologist at Simon Fraser University in Canada, jointly released A study shows that shark and ray populations have plummeted by 71% in the past half century since 1970. Not only that, three-quarters of shark species are endangered. Such a result made everyone, including professionals, feel "very shocked".

Dulvey told Red Star News that at this rate, many shark and ray species in the ocean may completely disappear within 10 to 20 years. Immediate global action is needed to ensure "a brighter future" for these animals.

↑Since 1970 to the present, the number of sharks and rays has plummeted by 71% in the past half century.

Pacuro added that they recently published the results of a new analysis in the journal Current Biology. According to the IUCN "Red List of Endangered Species" standards, more than 37.5% of the world's cartilaginous fishes (sharks, rays, chimaeras, etc.) are in danger of extinction.

"In a new global analysis, we assessed 1,199 species of sharks, rays and chimeras and found that 391 (32%) met the criteria of vulnerable, endangered or critically endangered. This is our assessment of cartilaginous fishes The second global assessment found that twice as many species are threatened than in the first analysis in 2014 (181 species). Warm-water, coastal sharks and rays are most at risk, with more than three-quarters of them at risk. Tropical and subtropical species are threatened," he explains.

↑Strays in the aquarium. According to Visual China

And behind this, human fishery production is one of the most important reasons. Research shows that almost all (99.6%) cartilaginous fish species in global waters have been affected by fishing, and among the 391 species of cartilaginous fish that are facing threats of extinction, overfishing is the common main risk faced by all species. Sharks and rays are particularly vulnerable to overfishing because they grow slowly, Pacullo explained.

In addition, approximately one-third of threatened cartilaginous fish species are threatened by habitat degradation, primarily caused by development (25.8%) and agriculture/aquaculture (9.5%).

↑Schematic diagram of the global ocean warming rate from 1960 to 2016.

Another important reason is global warming. According to the duo's research, global warming is affecting 10.2% (40 species) of threatened cartilaginous fish species. As heat waves sweep across the world this summer, another study also pointed out that heat waves have had a huge impact on marine life. It is estimated that 1 billion marine life has died from the high temperature on the coast of Vancouver alone.

Pacuro analyzed that climate change threatens marine ecology mainly through the following two channels. First, the risk of extinction of coral reef-associated marine species increases due to loss and degradation of marine habitats due to reduced coral cover due to bleaching and disease risks.

Secondly, rising seawater temperatures will lead to an increase in ocean acidity, and the oxygen content in seawater will also gradually decrease, making it no longer habitable. Some temperate species, such as the spiny ray (Amblyraja radiata), are declining at equatorial borders as rising water temperatures drive them out of their native habitats and even kill them. A previous scientific study showed that if the situation is not improved in the future, most organisms in the ocean will become extinct in 2100.

↑Global warming has reduced the area of ​​coral coverage, leading to the loss and degradation of marine habitats.

Dulvey said that scientific research has revealed an increasingly grim reality, that is, sharks and other cartilaginous fish species have become one of the most threatened animal lineages, and their extinction rate has approached that of terrestrial vertebrates. . The increasing likelihood of extinction of marine life suggests that marine ecosystems may face a future similar to that of terrestrial biodiversity. On land, the pressure of human production activities has led to the disappearance of many species and may make the earth facing the sixth mass extinction.

Sharks are heading towards "functional extinction". How will it affect marine ecology?

At the same time, over the past four years, American marine biologists Demian Chapman and Mike Hesas have used baits to remotely control water in 58 countries and regions around the world. Under the Camera (BRUV), a massive global shark survey was conducted. The results showed that of nearly 400 coral reefs around the world, no shark was found in 20% of the places.

Hesas said that this data itself clearly shows the seriousness of the problem. Chapman believes, "This is definitely a crisis." Not only that, this crisis is different from the past. Two marine biologists came up with the term "functional extinction" during their investigation.

↑Demian Chapman and Mike Hesas conducted a massive global shark survey using the Baited Remote Underwater Camera (BRUV).

The so-called "functional extinction" means that once the number of sharks is not large enough, they will no longer be able to play an important role in controlling the numbers of other marine life.

Dulvey said that as top predators, sharks play a vital role in the marine food chain. They can control the number of small predators and are very important to the marine ecosystem. In addition, they transfer nutrients from the surrounding seawater to the reef, as well as nutrients from the surface water into the deep ocean.

As a result, declining shark numbers not only risk species extinction and marine ecological imbalance, but also waste opportunities for sustainable fisheries, tourism and long-term food security. The simultaneous death of many marine species affects not only marine life, but also land life, from birds that feed on marine life to humans who operate fisheries and eat seafood.

Pacuro said that the sharp decline in shark numbers is undoubtedly like "an expanding black hole in the marine ecological chain." However, due to the huge scale and complexity of the marine food chain, there is currently no clear answer to what consequences the reduction in shark numbers will have on the marine ecosystem.

↑As apex predators, sharks play a vital role in the marine food chain.

But the far-reaching effects of "predatory species depletion" are becoming increasingly apparent in marine ecosystems. For example, declines in the abundance of predatory sharks and tuna are associated with increases in the abundance of medium-sized predators such as bony fish and smaller sharks, suggesting that the basic functions of these marine food chains are changing.

Dulvi and Pacullo told Red Star News that the current situation of sharks and rays has sounded the alarm. The most irreversible feature of the global biodiversity and climate crises combined is the loss of uniquely adapted populations and species.

Protecting global marine biodiversity is urgent but not easy

Dulvey said that this is not the first warning about the serious decline in global shark numbers. The first time in 2014 Global assessments highlight that one in four species is already threatened. However, due to mankind's insufficient understanding of marine ecology and the difficulty of protecting marine life, it does not seem to be easy to "turn the tide".

↑On April 22, 2021, in Dubai, United Arab Emirates, a group of environmentalists are releasing small sharks and other marine species bred in aquariums into the open sea.

“On land, we can monitor every bird with a tracker and set camera traps to capture the rarest land animals. In most cases, we have been able to track birds, mammals , the loss and recovery of species such as frogs and plants, and determining whether a species is safe. Habitat loss and degradation due to development, fire and deforestation can also be monitored regularly via satellites,” he explains. It is extremely difficult to assess changes in biodiversity status, and we have not yet achieved the goal of measuring population and species depletion through fishing mortality maps.”

So, in the face of such a severe situation, What should we do?

Dulvey said that countries around the world are falling far short of heeding scientific advice, fulfilling treaty obligations to end unsustainable development, protecting critical habitats and prioritizing the protection of cartilaginous fish species. He believes that now, there is an urgent need for countries around the world to unite and immediately implement sound fisheries management measures around the world, such as restricting the fishing of endangered sharks and rays and related trade activities, establishing marine reserves or setting up establishments in sea areas with frequent shark activities. No-fishing zones, etc., to prevent population collapse and “immeasurable” consequences to related ecosystems.

“This is also a response to climate change and will ensure improved ecosystem functions and fishery yields,” Durvey said.