Presumably, everyone has more or less heard of China's "water treasure" - the Chinese sturgeon.
On July 21 last year, the IUCN announced"China's national treasure wild Yangtze white sturgeon"Extinct. Even more distressing is the fact that 23 of the world's 27 species of sturgeon are threatened with extinction and 17 are listed as critically endangered by the International Union for Conservation of Nature (IUCN).
What kind of fish is this?Why does it affect the hearts of environmentalists at home and abroad?In this issue, let's talk about sturgeon.
Sturgeon refers to the fish of the order Sturgeon, also known as Chinese sturgeon, eel, and sturgeon, which belongs to the order Sturgeon of the class Bony Fish. Sturgeon is one of the earliest extant vertebrates, mainly distributed in the lower reaches of the Jinsha River to the estuary of the main stream of the Yangtze River in China, and is found abroad in the mouth of the Han River and Lijiang in North Korea, and in the western part of Kyushu in Japan.
Sturgeon is a demersal fish, which is a carnivorous fish, mainly feeding on river benthic animals in freshwater, and fish in the ocean, followed by crustaceans, and less molluscs. The survival water temperature of the sturgeon is 0 37, and the suitable water temperature for growth is 13 25, because the sturgeon is a large migratory fish, it begins to go up the river to the upper reaches of the Yangtze River in the summer and autumn of each year to spawn, and after the eggs hatch, the young sturgeon returns to the ocean along the river.
Since 1983, tens of millions of captive-bred Chinese sturgeons have been released from different research institutes and institutions in China. Even in Hubei, Sichuan, Shandong, Yunnan and other provinces, special flowing water aquaculture areas have been established. In Yunnan, Guizhou, Jiangxi and other provinces, the abundant mountain spring water in the mountainous areas is also used to build sturgeon breeding ponds near the water source by taking advantage of the characteristics of good water quality, high dissolved oxygen and large drop.
The commercial use of farmed sturgeon in the sturgeon farming areas of these provinces has also been successfully realized, and excellent economic benefits have been achieved.
However, with the increasing domestic requirements for aquaculture sewage treatment and discharge, whether it is commercial farming or public welfare release, sturgeon farming areas have to consider more environmentally friendly ways to breed sturgeon, and in recent years, some sturgeon farming areas have begun to pilot the use of factory circulating water systems to breed sturgeon.
Recirculating aquaculture system (RAS). Composed of purification system, temperature control system, aeration system and sterilization and disinfection system, the system can be designed according to the growth Xi, required environment and water quality requirements of different species, so as to realize the artificial breeding of sturgeon across seasons and regions.
First of all, in the construction of ponds, the fish ponds for recirculating water sturgeon farming can be made of round polymer plastic, PP ponds, or they can also be made of concrete materials. Pool depth 1 1About 5 meters, the water depth is 06-1 meters. It can rely on the geographical terrain to build an indoor environment, and it is generally recommended to use a steel structure workshop or a frame workshop.
Secondly, in the treatment of source water, whether groundwater or surface water is used, the water quality should be monitored and treated before entering the fish pond. If it is groundwater, it is necessary to strictly check whether the minerals in the water, such as arsenic, mercury, iron, manganese and other elements exceed the standard;In the case of surface water, in addition to monitoring the minerals in the water quality, the water needs to be sterilized to prevent harmful bacteria from mixing into the fish pond and causing fish diseases.
Of course, harmful minerals can be built into a static pond and sprinkled with drugs that can react with them in the water, so that they can be turned into powder and precipitated at the bottom of the pool. Generally, the clear water from the static pond surface can be introduced into the fish pond.
Thirdly, the optimal water temperature for sturgeon is 20 22, and the water temperature of the fish pond can be constant by using temperature control equipment. In addition, because the sturgeon is a bottom-dwelling fish, the dissolved oxygen requirements for water quality are higher, so the aeration cone can be used to aerrate the water at the back end of the water treatment, and at the same time, the aeration equipment is installed at the bottom of the fish pond to increase the amount of dissolved oxygen in the pond.
Finally, sturgeon in the juvenile stage have phototaxis, and when adults switch to benthic habitat, phototaxis disappears. Therefore, it is advisable to avoid direct sunlight in the fish pond, which is why it is recommended to keep sturgeon indoors.
In conclusion, the use of factory circulating water system to breed sturgeon can not only improve the efficiency of sturgeon farming, but also reduce the environmental load. We also expect that with the increasing improvement of the design and equipment research and development of domestic circulating water systems, we can participate more in sturgeon farming and make this endangered species "live" again!