"We're going to make a home for the native fish in the reservoir." The staff of the Xianlin Reservoir called, "Do you want to come and see?" ”
Of course it depends.
Today (March 31st), the smoke and rain are misty, and the Xianlin Reservoir in the west of Hangzhou City is hidden in the green mountains, quiet and beautiful.
On the shores of the cove, staff are busy "making homes" for the indigenous fish.
Together with the Xianlin Reservoir, the person responsible for the "home" project for indigenous fish is Chu Chenjiang, a staff member of the Fisheries Institute of the Hangzhou Academy of Agricultural Sciences.
Chu Chenjiang said, "Settling down is actually putting an artificial fish nest in the reservoir." "To put it bluntly, the artificial fish nest is to make an artificial delivery room for the fish."
Artificial fish nests, put into the Idle Forest Reservoir, hope that the fish can go to the inside to lay eggs, help them naturally reproduce and grow the family.
12 artificial fish nests, lined up on the shore. Chu Chenjiang said that this year is the first test, and no one can understand the rules, so they use all the ways they can think of.
There are 12 artificial fish nests, all of which are pvc control frameworks.
Divided into sizes, the big one is 4 meters * 2 meters, the small one is 4 meters * 1 meter, one is wide, one is narrow, Chu Chenjiang said, the density is not the same, you can grope, these fish like to be dense, or looser.
On the artificial fish nest, both plastic brushes and palm slices are installed.
Sub-materials. Under the frame, half tan, is hung with palm flakes, and half is green plastic brush. They all act the same way, "mimicking" plants so that fish can spawn inside. Chu said that both materials are soft and will not hurt the fish. But which effect is good, you have to try it to know.
Also divided into depths. Chu Chenjiang said that the green brush into the water is about 2 meters long, and the palm flakes are about 1 meter. Then, in order to know how deep the fish like to spawn in the water, the artificial fish nest has made a more three-dimensional "double-layer deluxe version", the two layers are bound together, and the deepest after entering the water is up to 4 meters, and then you can see which depth has the most eggs.
The staff used bamboo poles to sink the palm slices into the water as much as possible
Do all fish run to artificial nests to spawn? Chu Said, No.
In simple terms, fish spawning can be divided into three categories. Submerged, such as bream, step fish, fish eggs will sink to the bottom of the water; floating, such as the four major families of "grass carp", fish eggs will float to the surface.
There are also sticky eggs, such as carp, crucian carp, tuantou bream, etc., when they lay eggs, they must be attached to aquatic weeds, and the eggs can adhere to aquatic weeds and then slowly hatch.
Chu Chenjiang said that there is no particularly good "midwifery" means of submerged water and floating, but for sticky eggs can be used as artificial fish nests, so this time it is specially made for them 12, try it.
The artificial fish nest was ready, and at more than 2 p.m., braving the rain, the staff placed the artificial fish nest in the Xianlin Reservoir.
12 artificial fish nests, one in groups of four, one large and one small, are placed on three fixed points in the Xianlin Reservoir.
I followed the first installation team and got on a workboat, dragged four artificial fish nests to the stern, and ran deep into the Xianlin Reservoir. Arriving at the mouth of a bay with a depth of more than ten meters, the staff said, this is it.
In order to fix the artificial fish nest and bind the two ends, the staff climbed to a height of 5 meters on the shore and tied it to a tree.
From the top of the boat to the shore, a staff member jumped to the shore, dragged the rope to climb to a high place, climbed about 5 meters high, found a strong tree, tied it tightly, and fixed the end of the artificial fish nest.
Jump off the boat, drive to the other end of the shore, dock again, climb high, tie tightly. One end and one tail are fixed, and a row of artificial fish nests is fixed in this position.
Why do you have to climb at least 5 meters high?
Yang Ning, a staff member of the Xianlin Reservoir, said that the existing water level of the Xianlin Reservoir is 64 meters, and the normal water storage level should reach 70 meters, and the water level will rise, and the height should be reserved.
The artificial fish nest was fixed, and the green plastic brush, after entering the water, quickly stretched out, standing in the water like a huge water grass; the palm slices were still floating on the surface of the water, and the staff took out bamboo poles and pounded the palm slices under the water, saying that when it sucked up the water, it would sink.
The artificial fish nest is installed, and every 3-4 days, the staff will come to check it. See if there are any fish spawning, if you have some, collect some, bring them back for testing, and see what kind of fish eggs they have.
Installed artificial fish nests.
Now it is good, just in time for the breeding period of fish, wait until the end of May and the beginning of June, Chu Chenjiang said, the mission of the artificial fish nest is almost completed, then it is necessary to carefully count it, do data analysis, which size, which material, which depth, which kind of fish has the most eggs.
"The first trial this year, it's a bit more troublesome." Chu Chenjiang said that it will be convenient in the future, for example, in the future, the family of which fish in the Xianlin Reservoir wants to be larger, there is no need to breed and release, as long as it is liked, set up more than a few man-made fish nests to help it reproduce naturally.
Why put fish in the reservoir?
Standing at the edge of the Xianlin Reservoir, the Chucheng River let me look along the shore, and the circle was full of plants, trees and grasses. Chu Chenjiang said that when the water level rises, the plants that can now be seen by the naked eye will flood into the water in the future, and after a long time, they will rot.
Too many plants rot in the water, which will make the water rich in nutrients. If people go to tidy up a little bit, it is a very large project. But at this time, the fish can help.
For example, the yellow-tailed carp. It is a benthic fish, the bottom of the reservoir of attached algae, humus and organic debris, they are eaten in one bite, can decompose and consume the bottom of the reservoir organic matter and algae, so as to ensure water quality safety. Therefore, since last year, 120,000 yellow-tailed catfish have been stocked in the Xianlin Reservoir.
The setting up of artificial fish nests and the proliferation and stocking are all to make the fish family help make the water quality better.
In 2019, the Fisheries Institute did an aquatic biological resources survey in the Xianlin Reservoir, and there were 19 species of fish in the Xianlin Reservoir, mainly for crucian carp and catfish, such as horsefish, broadfin carp, river sand pond fish, etc., with a total of about 250,000 fish.
Moreover, the survey shows that the aquatic ecosystem of Xianlin Reservoir is still in the early stage of development, the abundance and biomass of plankton fluctuate greatly, and in the process of succession from terrestrial ecosystem to aquatic ecosystem, large benthic communities have not yet been constructed.
The establishment of artificial fish nests can promote the natural proliferation of indigenous fish species in the reservoir and promote the establishment of the entire fish community, thereby increasing the stability of the water ecosystem of the idle forest reservoir.
A few days ago, 7,000 small fish fry had just made their home in Danong Port in Jianggan District. In addition to them, Hangzhou's breeding and stocking activities have also begun this year.
The Hangzhou Fishery Station reported a figure that from January to December 2020, the number of fish fry stocked in Hangzhou's major rivers will reach 100 million!
Most of these 100 million are "four big fish" bluefish, grass carp, silver carp, bighead carp; as well as bream, bream, flower fish bones, bare lip fish, Chinese river crab, Chinese turtle, etc., basically achieving full coverage of Hangzhou's important fishery waters.
Why are so many fry stocked every year?
It can improve water quality and enhance the water environment. For example, silver carp, bighead carp, etc., for every 1 kilogram, can eat 30-40 kilograms of algae.
Replenish and restore fishery resources. Only by putting more can they "live" again. For example, the yellow croaker, which is on the verge of being "extinct", can be caught again in the past two years.
Help fishermen continue to increase their income. For every 1 yuan invested in fry, fish worth about 8.85 yuan can be fished.
Correspondent | Yang Ning