Swimming naked craps in Qinghai Lake
The chemical characteristics of the Qinghai Lake: the water with high hardness, low oxygen, generally in summer is greater than winter, surface is more than bottom and without anaerobic layers. Second, elements of biological nutrients in the lake, the nitrate content is very low, but with high iron and high silicate content, which indicate that the elements of biological nutrients in the lake are lower. Among them, the environment for growth and development of diatoms is proved by high silicon content.
Seaweed is a kind of Phytoplankton, the type and quantity of phytoplankton in Qinghai Lake
are not many, of which the most are diatoms, they almost occupied every corner of the bottom in the whole lake, some attach to the surface of the filamentous algae, and some attach the surface of the bottom silt. There also have some other kinds of seaweed, such as Green algae, cyanobacteria and algae in Qinghai Lake, except diatoms. Don’t underestimate these seaweeds, they prove the basic food for living of naked carp in the lake, so lake become more active and with full vitality.
Qinghai Lake is a typical constructed lake, once connected with the Yellow River, but later the water can’t flow into the Yellow River for the uplift of RiYue mountain, gradually it became a closed inland lakes with high salty, so the naked carp was appeared which was the unique creature in lake. The naked carp is a unique kind of large-scale commercial fish, a valuable rare aquatic animals, an important animal to protect. The body type was slight aside, with rounded head and proper mouth, but the naked body without scales. Actually , the ancestor of naked crap have scales, later because of increased altitude and radiation, lower water temperature, so their body’s condition can’t suit for this harsh environment. Therefore , on one hand they increased fats under their skins to add the amount of surface mucus secretion glands to regulate the osmotic pressure, precipitated harmful substances which erode the body and hindered particles which impede breathing, reduced water friction, Prevented the death caused by fluid solidification; on the other hand, changed environment promoted the naked crap to drill holes and rock crevice to prey, so the scales were not necessary to their flexible bodies. Therefor , the protecting function of scales gradually weakened until to disappear.
Because of different ages and physical development stage, the naked craps in Qinghai lake have consisted different ecological groups, they feeding, cruising, wintering or breeding eggs in the lakes and rivers, never stopped, even in winter they also constantly swimming and searching food in deepwater.
The group multiplication of naked craps through two processes of growth and reproduction to achieve. So the rivers along the Qinghai Lake have become the reproduction sites, such as Buha River, Shaliu River, Haergai River, Ganzi River, Baha Ulan River, and because of the relationship between ancient Qinghai Lake and the Yellow River, the source of fishes in Qinghai and Yellow River are similar, and the members of some fish in Qinghai can be find the same or similar to species in the Yellow River.
Buha River is the largest river injected into the Qinghai Lake, which is located at the northwest of Qinghai Lake, the river’s area nearly half of the Qinghai Lake. The Buha waters show the shape of branch, both banks tributaries asymmetry, the right bank relatively short, the left relatively dense, with many tributaries and abundant waters.
May to July, naked craps enter the spawning period, tireless fish together in entrance of Buha River, that’s a spectacular scenes. When the little fish are born like branches spread out in Buha River tributaries and streams of water, after growing older they will follow the water swimming into downstream to Qinghai Lake. This is a difficult process, there also has the risk of death, but they have to do this. This scene also known as "migration."
The Buha River entrance is not far away from Bird Island, when sun shines in summer, you can see the scene that survived fish through hardships scrambling to Qinghai Lake with thinner body under the crystal clear water, that’s like every homesick person walking on the way home.
Naked carp often inhabits in fast-flowing, gravel-covered river or small lakes with marshes , or shallow stage with slow water or more eroded stuff, they scrap the seaweed as food from the stone, such as filamentous algae, shrimp hook, plant debris and other benthic organisms. Because it locates at plateau with an altitude over 3000 meters, the highest monthly average temperature have never reached 15 centigrade, five months of the year are freeze period, moreover, the food can provided for naked craps reduced with the constantly increased salinity, colder water and less plankton species. Therefore, the growth period of naked craps is slower, no significant changes in body growth stage, so there has a saying "growing 0.1 catty in a year, growing one catty in ten years". From the point of physical and chemistry to analysis, Qinghai Lake is shortage of nutrition, the food available to naked craps are less, so the living condition of naked craps in Qinghai Lake is more difficult than the lower altitudes areas.
Artificial restocking station of naked craps was built by the Ministry of Agriculture, the State Planning Commission in Shaliu Riverside in Gangcha County, covering (about 12,667 square meters), there are 571 square meters for fish hatchery workshop, Kinship naked craps holding tanks and micro-circulation water fish breeding ponds have 3000 square meters and other ancillary facilities, it is the public welfare institutions under the govern of rescue center of naked craps. It charges important responsibility of the quality rescue, proliferation discharge, fisheries resources and ecological Environment census detection.
Up to now, the station has been increased the number of large-sized naked carps about 7million to discharge.From 2007, a total number about 34 million have been discharged. So this guaranteed source and quality of the egg, and in the spawning rivers they made water forecast and annual monitoring of resources to improve and supplement the basic database of fishery resources in Qinghai Lake.