Many people will think that Qiandao Lake is a naturally formed lake, but in fact it is not, on the contrary, Qiandao Lake is the largest artificial lake in China's Yangtze River Delta, and its other name is "Xin'anjiang Reservoir". It took 5 years to build in 1960, the entire reservoir has a storage capacity of 17.8 billion cubic meters, when it is at the highest water level, there will be thousands of road bridge islands, so it is called Qiandao Lake.
Qiandao Lake is one of the highest quality lakes in China and a first-class water body of the country, so Qiandao Lake shoulders the heavy responsibility of supplying water to surrounding cities. As an artificial ecological lake, Qiandao Lake has naturally become a well-known fishing and breeding area in the country, and the silver carp and bighead carp produced are of extremely high quality, and have been loved by the market for many years.
<h1 class="pgc-h-arrow-right" data-track="32" > water conservation and fishing</h1>
Qiandao Lake promotes the development model of "water conservation fishery" with characteristics, that is, to maintain the ecological environment of Qiandao Lake through the mode of "water retention with fish" and "water with fish". The fish species in the entire Qiandao Lake area are quite rich, reaching 114 species, which directly drove the local industrial and economic development of 5 billion yuan in 2019. Therefore, the fishery of Qiandao Lake can be said to have a considerable economic value.
On December 1, 2020, the local fishing team fished in the southeast lake area of Qiandao Lake, harvesting more than 10,000 kilograms of silver carp and bighead carp, and the first fishing in 2021 was more than 30,000 kilograms of silver carp and bighead carp. According to the current organic fish farming model, it is conducive to the formation of a good ecosystem and the real realization of fish water conservation.
<h1 class="pgc-h-arrow-right" data-track="37" > historical legacy</h1>
However, the current sustainable fishery development model of Qiandao Lake has not been formed since the beginning of the establishment of the reservoir, but has only been proposed in recent years. When the Xin'anjiang Reservoir was first built, local fishermen basically farmed economic fish such as sea bass and catfish through cages. The biggest problem with this farming model is that the bait and fish manure are not cleaned up, which directly pollutes the local water quality, resulting in the beginning of the emergence of water eutrophication in Qiandao Lake.
Not only that, the development around Qiandao Lake, such as the establishment of tourist attractions, the construction of orchards, tea gardens, etc., has also inadvertently had a certain impact on the water quality of Qiandao Lake.
A series of operations have led to a significant decline in the water quality of Qiandao Lake, the problem of local eutrophication of water bodies, and some algae have begun to proliferate abnormally. In the 20 years from 1980 to 2000, there were three cyanobacterial blooms in Qiandao Lake.
In addition to the impact of temperature and environmental changes, the inappropriate stocking of human species can be said to be the culprit of cyanobacterial blooms. The abundance of nutrients and salts in the water will promote the proliferation of cyanobacteria, spirulina, etc., and then cause the saprophyll plants in the water to begin to rot, age and die. We will feel that there is a layer of oil film covering the surface of the water, and the fishy smell is very obvious. This eutrophication of water bodies can also lead to a further decline in fishery production.
<h1 class="pgc-h-arrow-right" data-track="45" > strengthen supervision</h1>
The contamination of water from an important source of domestic water for residents is a big deal. After the discovery of unusual water eutrophication, the fisheries of Qiandao Lake also began to regulate the stocking and fishing of fish, prohibiting any unit or individual from fishing silver carp in the water, after all, they are mainly hunting these algae, and their presence can effectively reduce the excessive eutrophication of algae in the water.
However, the process of water eutrophication has not stopped there. There are still abnormal algae growth in many areas of the Xin'anjiang Reservoir, and the risk of large-scale blooms is still relatively large. Now Qiandao Lake proposed to retain water with fish is actually the same reason, the appropriate fish species can effectively alleviate the problem of water eutrophication.
This model of water conservation with fish is indeed more sustainable and ecologically friendly. However, it cannot fundamentally treat the problem of water eutrophication, and can only be said to control the density of algae. Because the changes in the water quality and environment of lakes are the root causes of water eutrophication.
In fact, most of the well-known lakes in our country are facing the problem of water eutrophication, and it is a stubborn disease that is difficult to eradicate. If the algae in the lake is not monitored in real time, harmful algae are likely to erupt suddenly.
For all lake management, it is important to pay attention to the prevention and management of water eutrophication. It is necessary to establish a relevant pre-mechanism for monitoring algae and take timely measures to avoid large-scale bloom events. Secondly, it is also necessary to standardize the stocking and breeding of fish in lakes, reasonably determine the proportion of stocking, and give full play to the water retention function of organisms.
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