The first net cage breeding finless porpoise returns to natural waters

  Researchers hope to use this to accumulate experience for finless porpoise population conservation and artificial conservation

Babe in the cage jumped out of the water. Photo by Ding Zeliang

  The Yangtze finless porpoise is unique to my country's freshwater dolphins. Because of its scarcity, it is called "the giant panda in water". Cage rearing and breeding are a means of conservation, and ultimately hope finless porpoises return to nature and participate in natural population breeding.

  Beijing News July 6, Beibei finless porpoise left his parents and lived "home" for 4 years. It was released into the natural waters of the old road of Swan Chau Yangtze River, to greet the future journey alone, and to find new partners.

  Hao Yujiang, Ph.D., Institute of Hydrobiology, Chinese Academy of Sciences, said that as the first finless porpoise to breed in cages, Babe returned to natural waters. Researchers hope to use this to test whether finless porpoises born in an artificial environment can also adapt to the wild environment and accumulate experience for finless porpoise population protection and artificial conservation techniques.

The finless porpoise once rescued has a "child"

  The Yangtze finless porpoise is unique to my country's freshwater dolphins. Because of its scarcity, it is called "the giant panda in water". According to the 2017 scientific research, the number of finless porpoises in my country is only 1,012.

  The 4-year-old babe is a female finless porpoise. It is round and weighs 60 kilograms. It is experiencing the "tail" of puberty. Unlike other finless porpoises, Beibei is the first finless porpoise born and raised in an artificial cage environment. On May 22, 2016, Beibei was born in the cage of the Hubei Changjiang Swan Island Baiji Dolphin National Nature Reserve. Its father was raised every day in the cage environment after the rescue of the Swan Island old ice disaster in 2008.

  The cage is located in the waters on the north bank of the central part of the Swan Island Old Road, with an area of ​​225 square meters and a net clothing depth of 7 meters. It was originally designed as a temporary rescue facility for finless porpoise rescue.

  In 2008, most areas of southern my country suffered from extreme cold weather for a long time, which caused the Swan Island to freeze. It is understood that Swan Chau's old path was formed in 1972, and there has never been ice in history before. After freezing in 2008, the finless porpoise breathed out to break the thin ice layer. Because the finless porpoise's skin is very delicate, the edge of the broken ice layer is as sharp as a knife for them.

  During the ice disaster that year, researchers collected five specimens of dead finless porpoises, including two pregnant female finless porpoises. "The skin on their stomachs was cut by a sharp weapon, and was obviously scratched by the broken ice." Hao Yujiang recalled that there were still some scratched finless porpoises who were treated in time and their skin healed quickly. Too. "We chose two small male finless porpoises, named Tiantian and Zhouzhou respectively, to try to rescue and raise them in cages."

  In 2010, the protected area introduced a female finless porpoise into the cage from the old Swan Island, named E'e. The "love crystal" of Tiantian and E'e is Babe.

More than two months of "wild training" to learn their own fishing

  Although Tiantian and Zhouzhou are well adapted to life in cages, researchers still need to "examine" whether they can return to the wild after artificial rearing and domestication. In 2011, through soft release, Zhou Zhou returned to his old hometown of Swan Chau. Together with the release, there was also the finless porpoise Abao who had been kept in the Baiji dolphins in the aquatic institute of Chinese Academy of Sciences for 7 years.

  Three months later, the scientific researchers were glad to find that the finless porpoise, which had lived in an artificial environment, still has the ability to survive in the wild. "In 2015, when we checked for finless porpoises, we found that A Bao returned to the old home of Swan Chau and participated in breeding. His grandchildren have reached 10 finless porpoises, and there are two'great-grandchildren'."

  Hao Yujiang said that cage breeding and breeding are a means of conservation, and ultimately hope that finless porpoises return to nature and participate in natural population breeding. Today, the 4-year-old Babe has also reached the best moment to be released. "Before one year old, finless porpoises cannot leave their mothers due to nutritional needs. At a larger age, finless porpoises must learn survival skills from their mothers, such as fishing, detecting the surrounding environment, etc., so releasing them too early is not conducive to the lives of animals. The shellfish is close to sexual maturity, and if it continues to be raised in the cage, it will be impossible to participate in the breeding of the population."

  Unlike Zhou Zhou and A Bao who were born in the wild, Babe has never lived "independently". In order to make it suitable for the natural water environment in advance, the staff conducted "wild training" for Beibei for more than two months. In the past, Beibei was used to eating frozen fish. It first needed to gradually adapt to the taste of live fish and learn to actively fish.

  "This domestication process is more difficult than imagined." Hao Yujiang admitted that Beibei did not adapt at first, and did not have the desire to take the initiative to fish. Feeding live fish sometimes became angry and refused to eat. "We thought of a lot of ways, and we have experienced repetitions in the process." This further enriched the scientific researchers' understanding of the learning ability of the finless porpoise. "Tiantian and E'e have another baby this year. We may have to redesign the domestication process of this newborn finless porpoise. If the ultimate goal is to release it into the natural environment, it may be necessary to domesticate its catch at an earlier stage. Fish capacity."

  For four years, Beibei has lived in a small cage. In order to make it familiar with the wide water surface of the old road, the staff of the reserve also set up a fence of 20,000 square meters to allow it to swim in the waters close to the natural environment.

Can be identified later by the built-in label

  The repatriation was originally scheduled to take place on July 8, but due to heavy rain, the water level of Swan Chau's old road increased, and the installed adaptive fence was almost completely submerged, so the repatriation was advanced to July 6. Researchers hope to use this to accumulate experience for finless porpoise population conservation and artificial conservation.

  "Once animals are placed in the wild, it is difficult to track them, and there are great technical difficulties in long-term tracking." Hao Yujiang said that Beibei has a built-in tag implanted on it, and scientific researchers will later identify Beibei based on this. "We will also conduct an overall monitoring of the finless porpoise in the old area. In the future, if the babe is caught, the scientific and technical personnel can identify it through the label scan code and genetic samples and understand its survival status."

  The recent heavy rains in the south have an impact on the finless porpoise's "ride the wind and waves"? Hao Yujiang said that finless porpoises are aquatic mammals. They are not afraid of water, and will not have much impact on the whole. However, if the flood is particularly large, the woodland around the road is submerged, and the finless porpoise enters the woodland area, which may cause stranding, or the finless porpoise may enter the low-lying area through the breach of the embankment with the flood, which will cause a fatal threat to the finless porpoise. "But this probability is relatively low, because finless porpoises are very intelligent animals and will actively avoid these areas."

  In addition, as the water level rises and the continental beach is submerged, prolonged immersion will rot the continental beach plants, have a certain impact on the water quality of the old road, and may also affect the health of fish and finless porpoises to a certain extent. Wind and rain are often accompanied by thunder and lightning, and the violent stimulation of natural phenomena may also affect newborn finless porpoises.

  Hao Yujiang said that various protected areas will strengthen inspections, and the patrols formed by civil organizations and fishermen will also play an important role. Once relevant conditions are discovered, they will be reported to the protected areas or scientific researchers in time to strive for timely treatment.

 -Conversation

  The threat of finless porpoise population survival

  Beijing News: What is the current population of finless porpoise?

  Hao Yujiang: Judging from the situation of several scientific investigations, the total number of finless porpoises was 1800 in 2006 and 1045 in 2012. The population showed a rapid decline from 2006 to 2012. The number of inspections in 2017 was 1012, that is, from 2012 to 2017, the population was relatively stable. Statistically speaking, there is no significant difference between the two data.

  Although the rapid decline of finless porpoise populations has been contained, the threat of population survival still exists, and the protection situation remains grim.

  Beijing News: What caused the rapid decline of the finless porpoise population from 2006 to 2012?

  Hao Yujiang: Fishery activities and the encroachment of the Yangtze River coast are the main reasons. The overall reason is that the environment of the Yangtze River continued to deteriorate at that time and for some time before.

  From 2012 to 2017, the reason why the rate of population decline was contained is that on the one hand, there may be factors of the population's own changes, on the other hand, it is also because after the results of the 2012 survey came out, it gave everyone a strong signal that the population of finless porpoises has declined. Too fast. The national agricultural department has issued a series of finless porpoise protection measures, and private groups have established patrol teams, which have played a role in promoting the ecological protection of the Yangtze River.

  Beijing News: How to carry out finless porpoise protection work?

  Hao Yujiang: Overall, the finless porpoise protection strategy has not changed much from decades ago. One is in situ conservation or nature conservation, which is to establish nature reserves in its main habitats, so that natural populations can be effectively protected or restored.

  The second is ex-situ conservation. Ex-situ conservation areas are a very important supplement to nature protection, especially during the period when the overall ecological environment of the Yangtze River tends to deteriorate in general, this work is particularly urgent. In 1990, the aquatic institute of the Chinese Academy of Sciences and other units first started the ex-situ conservation of the Yangtze finless porpoise in the old road of Swan Chau. At present, there has been an ex-situ conservation group of about 80 finless porpoises in the Yangtze Swan Chau Baiji National Nature Reserve.

  Then there is artificial breeding, which may not be a very important means of conservation, but its support for scientific research and public education cannot be ignored.

  Beijing News: What are the prospects for finless porpoise protection?

  Hao Yujiang: At present, the ecological environment of the Yangtze River and the protection of aquatic organisms are developing in a good direction. For example, the state officially implemented the 10-year Yangtze River Fishing Prohibition Plan from January 1, 2020. This is a big move, and it is very good news for the conservation of the Yangtze River’s living biological resources. At the same time, the state's efforts to improve the coastline of the Yangtze River are gradually increasing. Some illegal docks have been cleared and demolished, and a large number of natural coastlines have been restored. This will play a positive role in the restoration of the ecological environment of the Yangtze River. In addition, the state's control of sewage discharge from factories along the Yangtze River is becoming stricter. I am personally optimistic about the prospects for the protection of the Yangtze finless porpoise and other Yangtze aquatic life.

  Beijing News reporter Zhang Lu