Report on the investigation of finless porpoise: stone slope protection leads to the decline of habitat quality of finless porpoise
Xinhuanet Beijing, November 24 th In 2017, the Yangtze finless porpoise ecological science expedition team sailed for 1,300 kilometers and recently arrived at the Wuhan Fishery Wharf of the Yangtze River Office. At this point, the investigation of finless porpoises in Wuhan-Yichang River section ended. Today (November 24), the expedition team will set off from Wuhan again to conduct a round-trip inspection from Wuhan to Shanghai.
Preliminary confirmation of 70 records of 102 finless porpoises.
During the investigation from Wuhan to Yichang, the expedition team found the Yangtze finless porpoise 59 times and 165 times, and the preliminary analysis of acoustic monitoring data confirmed 70 times and 102 times (note: 70 times refers to the number of finless porpoises observed; 102 times refers to the sum of the number of finless porpoises observed in these 70 times. This result is significantly higher than the number of observations in this region in 2012, which is equivalent to the observation results in 2006.
The relevant person in charge explained that at present, this is only a preliminary observation result, and the specific population estimation will be analyzed and compared as a whole after the whole investigation.
Finless porpoises are relatively concentrated and increasingly spotted.
As for the distribution pattern of finless porpoises, the results of this investigation are basically the same as those in 2012 and 2006, showing a trend of relatively concentrated distribution and increasing spotting.
According to the relevant person in charge, on the whole, the Yangtze section of Honghu Nature Reserve, the waters 30 kilometers above and below Jingjiang Gate in Jianli County, Yichang City and the waters under Gezhouba are the areas with high distribution density of finless porpoises. Among them, the distribution of finless porpoises in the upper and lower waters of Jingjiang Gate (above the mouth of Dongting Lake) is the most dense, and the witness rate is significantly higher than that of the previous two investigations.
It is worth noting that finless porpoises were found in the waters near Xinchang Town and Tashiyi Town in Shishou Nature Reserve. Previously, the Yangtze River freshwater dolphin survey in 2006 and 2012 failed to find the distribution of finless porpoises in Shishou Nature Reserve. A group of 3-4 finless porpoises have been living in the waters of Yichang Yanshouba since 2008, and this small group has been discovered again in this investigation.
In addition, the expedition team found a group of about 8-10 finless porpoises in the waters near No.1 lock 500 meters below Gezhouba. According to Yichang Fishery Administration, this finless porpoise group swam in the spring of 2017 and has been settled here ever since.
At the same time, the expedition team used fishery speedboats to inspect many navigable braided rivers, and found three finless porpoises in the waters of Guanzhou braided river in zhijiang city. The relevant person in charge explained that this shows that the Chajiang River is also an important water area where finless porpoises inhabit, which is of great significance for comprehensively grasping the distribution waters and overall quantity statistics of finless porpoises.
"Stone slope protection leads to the decline of finless porpoise habitat quality"
Judging from the overall environment of the current investigation, the above-mentioned person in charge analyzed that many scattered small docks have disappeared, and some regional beaches have also been naturally restored. However, the clear water discharge has obviously scoured this area, and a large area of bank collapse can be seen. In order to stabilize the river and waterway regulation, a large number of riprap revetment or continent protection have been carried out in this area. The natural muddy or sandy shoal waters turn into hard slope protection and steep bank, which may lead to the decline of habitat quality of aquatic organisms such as finless porpoises. Unmanned aerial vehicle remote sensing was used to monitor the beach environment along the Yangtze River. After the expedition, all aspects of information will be integrated to make a comprehensive assessment of the status quo of the finless porpoise’s habitat.
In addition, during the inspection from Yichang to Wuhan, a total of 1986 sailing cargo ships were counted, with an average of nearly 50 cargo ships passing by every half hour, with a high density. The above-mentioned person in charge believes that this will obviously increase the survival pressure of the Yangtze finless porpoise. The expedition team also recorded a total of 353 fishing boats in this section of the river. The overall density is not high, and the main operation method is gill net.