Can the Yangtze River’s fishing ban keep the next “white dragonfly”?

Recently, China’s Ministry of Agriculture and Rural Affairs issued a circular, said that from January 1, 2020, the Yangtze River basin 332 nature reserves and aquatic species resources protected areas to completely ban production fishing; Almost at the same time, The Holistic Environmental Science published an online paper, “What lessons the extinction of the white stork has left on the conservation of the Yangtze River” (hereinafter referred to as “The Extinction of the White Stork”), which said that the rare species of the Yangtze River in China, the Yangtze River, was presumed extinct in 2005-2010.

Source: Yuan Yixue Han Tianqi, China Science Journal

“The number of not into the pond, the fish is invincible food also. “The Yangtze River was once the most abundant basin of freshwater fish in China, now, the Yangtze River fish, such as the white herring, the white porpoise, the Yangtze River herring and so on have declared “functional extinction”, more and more Yangtze River fish are on the verge of extinction.

Exhausted and fishing is no fish, the Yangtze River fishing ban will keep us the next “white dragonfly”?

What is functional extinction?

“White slug extinction” newsletter author, china’s Academy of Aquatic Sciences Changjiang Institute of Aquatic Research researcher Wu Qiwei said in an interview with the media, “White slug extinction” is based on the results of the model calculation, the model is mainly based on the past literature and researchers recorded in recent decades of fishing records, in addition, also based on 1981 – There were 210 sightings in 2003, which led to the inference that the white stork was extinct between 2005 and 2010.

In September 2019, the International Union for Conservation of Nature (IUCN) organized a team of experts in Shanghai to assess the extinction of the Yangtze River, a unique species and national-level conservation animal.

Experts from the Institute of Aquatic Biology of the Chinese Academy of Sciences, led by Cao Wenxuan, a member of the Chinese Academy of Sciences, have for years called for a fishing ban on the Yangtze River.

Liu Huanzhang, a team member and researcher at the institute, told China Science Daily that it was prudent to declare a species extinct. “The traditional standard for IUCN is that no biological individual has been seen in 50 years, and now the academic community has acknowledged that there is ample evidence that the species have disappeared. “

But Mr Liu admits that negative evidence is difficult to prove.

“We’ve seen a species that can confirm its existence, but we can’t see a species that can’t logically put it into being non-existent, and it’s much more difficult to prove species extinction.”

So at present, the academic community often said that ‘functional extinction’ is to some extent a compromise wording, the conclusion of the functional extinction of the white slug is not a problem in the academic community. “

Despite their reluctance to accept, “everyone respects the IUCN’s evaluation model and experts”.

The academic team that published the paper, the Yangtze River Fisheries Research Institute of the China Academy of Aquatic Sciences, never gave up on pursuing the white slug. In 2017, the hospital led a survey of the Yangtze River’s fishery resources and environment.

During the survey, the researchers divided the Yangtze River into a grid of 20 kilometers to gather relevant information. Despite filtering the Yangtze River like a sieve, the researchers found no trace of the white slug.

As for the causes of extinction, the paper notes that low reproduction rates may be the main reason. Since the Yangtze River white stork is not kept in captivity and no living tissue is preserved, it is considered extinct according to the IUCN Red List.

Yangtze River fish in urgent need of protection

The authors also called for the extinction of the Yangtze River’s white slugs to be caused by multiple causes, indicating the urgent need to protect endangered Yangtze River fish.

Such fears are not unreasonable, and the Chinese and Yangtze River dragonflies, which share the same species as the white dragonflies and also live in the Yangtze River basin, face the same dilemma.

In order to protect these three species, the State as early as 1983 to include them in the List of Priorities for the Protection of Wildlife.

In 1989, these three species of mackerel were again included in the National List of Key Wildlife Protection, the first level of priority protection of animals.

According to the findings of the Institute of Aquatic Biology of the Chinese Academy of Sciences, from 1997 to 2017, the number of spawning spawning in the Yichang River section of the lower reaches of Gezhouba was gradually reduced, and the spawning time was postponed from the end of October to the end of November, and the number of spawning spawning was reduced from 2 times per year to 1 time per year.

In 2013, 2015, 2017 and 2018, there was no spawning activity in the Yangtze River.

In 2018, a survey conducted using underwater sonar at Yichang spawning site in the lower reaches of Gezhouba showed that the number of Chinese dragonflies was less than 20.

On January 3rd, the IUCN said via its official microblog that the final results of the ongoing comprehensive assessment of the Asia-Europe fish had not yet been released and that it was expected to update the Red List of Threatened Species during the World Conservation Congress in June this year, as well as officially release the results of the assessment and the corresponding level adjustments.

The ban on fishing in the Yangtze River is imperative

“Overfishing and baiting have long caused sustained damage to the ecosystem, biodiversity and fish resources in the Yangtze River basin. “

Liu Huanzhang explained that although the short-term fishing ban for several months a year can also play a role, but the fishing ban is too short to allow fish resources to recover, “often during the fishing ban has an effect, after the end of the fishing ban as usual or to carry out greater intensity fishing.”

Wang Yamin, an associate professor at Shandong University’s School of Oceanography, told the China Science Daily that the fishing ban is certainly beneficial to the restoration of fishery resources, but doubts are raised about whether the restoration of the Yangtze River’s ecological environment will play a decisive role, as there are more factors affecting the ecological environment of the Yangtze River.

“For example, the Yangtze River shipping and water conservancy projects have a relatively large impact on the yangtze river’s biology and ecology. “

In this regard, Liu Huanzhang said that the Yangtze River shipping, water conservancy projects and environmental pollution are the impact of the Yangtze River biological and ecological factors, “but governance needs to step by step, one aspect to carry out.”

The imposition of a fishing ban over a longer period of time would certainly have a great effect.

This effect refers to the increase in fish stocks and the overall population of species.

From the perspective of the overall ecosystem function of the Yangtze River, the fishing ban has a positive effect on the ecological protection and restoration of the Yangtze River water body, the maintenance of the ecological diversity of the Yangtze River and the improvement of the social ecosystem environment.

In Cao Wenxuan’s view, the reason for the temporary ban on fishing in the Yangtze River for 10 years, because many economic fish in the Yangtze River generally three or four years of sexual maturity, 10 years can allow the Yangtze River fish breeding 2 to 3 generations.

“The growth of stocks of this size will allow for a more significant recovery in fish stocks and, if the recovery is in good condition by then, appropriate use on a case-by-case basis.” “

Scientific planning of the Yangtze River fishing ban model

How should the Yangtze River be banned? The controversy in the academic circles has focused on the use of lakes.

For a long time, the Yangtze River basin, large and small lakes are tongjiang lakes, connected with natural waters, rising water in summer, winter water level drop, fish in the Yangtze River and lakes exchange.

However, due to flood control and resource development and utilization purposes, the Yangtze River basin lakes began to build locks, and the Yangtze River barrier.

“The fish diversity of Tongjiang lakes is high, the ecosystem structure formed by long-term evolution is stable, and there is mutual adaptability between the Yangtze River. “

Liu Huanzhang said that after the construction of the gate, the diversity of fish, ecosystem structure has become incomplete, imperfect function, resulting in the Yangtze River basin lakes eutrophication, biodiversity decline and other issues.

If there is a common view on the issue of the Yangtze River main stream and tributary fishing ban, there is still controversy about whether the lakes in the Yangtze River basin can engage in fisheries and how to engage in fisheries.

At present, there are voices that the Yangtze River basin lakes should also be completely banned from fishing, but Cao Wenxuan stressed that the Yangtze River fishing ban can not be “one size fits all”, there are some lakes of the fishery model not only did not cause pollution in the Yangtze River basin, but also the whole lake ecological cycle and water purification play a positive role.

From the scientific point of view, the best model of the Yangtze River fishing ban is to carry out a permanent fishing ban in national nature reserves, key basins and key waters can be used to a certain extent according to certain patterns, in lakes, reservoirs and other man-made waters, under reasonable scientific management, there can be a certain fishing industry.

At the end of December 2019, the Guidance on Promoting the Development of Large Water Fisheries proposed that under the new era, we should change the development mode of large-surface fisheries, realize the full integration of ecological protection and fishery development of large surface water sand, and promote the coordinated development of water ecology, production and life.

“Due to water, land, and time-based conditions, the goal of ecological protection and restoration in the Yangtze River basin is finally achieved.” Liu Huanzhang said.

Related papers information:

https://doi.org/10.1016/j.scitotenv.2019.136242

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