Measures for Fisheries Reconstruction after Rain and Snow freezing disaster in South China

Since the beginning of January 2008, the freezing weather of rain and snow has had a serious impact on fishery production in many provinces and cities in southern China. According to incomplete statistics, the loss of frozen fish and shrimp in southern provinces exceeds 10 billion yuan. In view of this, this paper puts forward some measures and suggestions for the reconstruction of freshwater fisheries after the rain and snow freezing disaster in the south for reference.

The type of disaster

In terms of aquaculture species and regions, the current disasters are mainly divided into the following types:

1. Tilapia aquaculture: tilapia aquaculture has suffered the heaviest losses in the cold wave this winter. Tilapia raised in ponds with a depth of less than 2.5 meters in some major producing areas such as Guangdong and Guangxi are basically frozen to death (except covered greenhouses and some cold-resistant species).

two。 Mandarin fish culture: the main problem in mandarin fish farming is that all feed fish freeze to death, resulting in tens of thousands of tons of mandarin fish in ponds without feed fish to eat.

3. Other high-quality fish: some poor cold-resistant high-quality fish, such as Thai bamboo shoot shell, Australian bamboo shoot shell, gem perch and some estuarine fish, also suffered heavy losses in this cold winter.

4. Macrobrachium rosenbergii aquaculture was seriously affected, and Penaeus vannamei also suffered losses to a certain extent.

5. Traditionally cultivated mud carp: due to a long period of low temperature this year, coupled with a lot of cold rain, most of the fish froze to death.

6. The destructive power to the seedling production field: the severe cold almost causes most of the freshwater seedling farms in the south to suffer losses to varying degrees, which will bring pressure to the next step of resuming production.

Measures for disaster reduction and resumption of production

The purpose of the measures for disaster reduction and resumption of production: (1) to ensure that the farmers affected by the disaster have a stable income in the year of resumption of production. (2) to put production into normal operation as soon as possible. (3) to increase effective social supply and alleviate the upward pressure on social food prices as a result of the disaster.

1. Resumption of tilapia production

The main results are as follows: (1) the overwintering seedlings should be released to improve the growth rate and try to be put on the market earlier. When the water temperature is stable above 18 °C, the seedlings can be released. It is suggested that 700g / mu can be stocked and the market specification of more than 500g / tail can be developed from August to October.

(2) early reproduction, early bidding, early listing, and strive for three crops in two years. Nursery farms covered with plastic greenhouse or other thermal insulation facilities can strive for early propagation of tilapia seedlings, release standard coarse seedlings, and strive for listing as early as possible in the same year (October to November). At the same time, the matching seedling cultivation techniques of several ponds were used to strive for the listing of three crops of tilapia in two years.

(3) after freezing, fish are prone to water mildew, so do not use drugs indiscriminately, especially malachite green and gentian purple, so as not to cause product quality and safety problems and affect the development of the whole industry.

two。 Resumption of production of mandarin fish

(1) early breeding of common carp and crucian carp to solve the problem of mandarin fish feed fish.

(2) to collect three dace (mud carp, Thai wild dace and Murray Gallagra dace) in reservoirs or deep ponds as parent fish, strengthen cultivation, and strive to restore production to the normal level in the fry farm as soon as possible.

3. Other high-quality fish can be adjusted, such as snakehead (raw fish), @ # @ 243fish @ and other fast-growing species on the market, so that the fish farm can operate normally.

4. During the process of resuming production due to the freezing death of a large number of mud carp in the fishing ponds where the four major domestic fish are raised, the stocking amount of grass carp and crucian carp can be increased appropriately, so that the total yield can be maintained.

Management measures of resuming production in early spring

With the passing of the severe winter, the current temperature and the water temperature of the pond will rise slowly. With the rise of temperature and the alternation of cold and warm air flow in early spring, the daily management of ponds should be done in the following aspects:

1. Frozen fish in the pond should be fished out in time, can be used as fruit and other planting base fertilizer, or for harmless treatment, the edge of the pond should be disinfected with quicklime and bleach.

two。 When the weather is sunny, the water level of the pond can be lowered appropriately to accelerate the rise of the water temperature of the pond.

3. When the southeast wind and rainy time are long and the water temperature is 16 ℃ ~ 22 ℃, the naked-bellied flea in the pond is easy to breed in large numbers, which is very easy to cause anoxic flooding in the pond, which should be paid close attention to. Once found, it should be controlled by trichlorfon or trichlorfon in time. At the same time, start the aerator to increase oxygen.

4. When there is a high temperature in a sunny day, the aerator can be turned on at noon to speed up the heating of the pool water and increase the amount of dissolved oxygen in the pool water.

5. Early spring is the season for the onset of protozoa, such as rotifer, bell worm, etc., should be checked frequently, once found, timely treatment, so as not to send bacterial diseases.

Suggestion

The loss caused by this low temperature disaster weather is huge, which has exposed the weak side of applied basic research. In the future, research and investment in the following aspects should be strengthened:

1. Strengthen the research on the breeding, popularization and application of cold-resistant varieties.

two。 Strengthen the infrastructure of the pond. For example, some reformed ponds with a depth of 3 ~ 4 meters have suffered minor losses in this frost disaster. Therefore, it is necessary to strengthen the transformation of the pond.

3. The mechanism of disaster prevention and mitigation, including meteorological, administrative directors, scientific research institutes, universities and other technical departments, should be further improved to deal with disasters.