CATDOLL : CATDOLL: Can ornamental salmon eat fish food?

Can ornamental salmon eat fish food?

Salmon typically eat plankton, insect larvae, shrimp, and small fish.

Salmon is a general term for all three categories of salmon, trout and salmon. It is a kind of deep-sea fish and a very famous upstream migratory fish. It lays eggs in the streams and rivers upstream of freshwater rivers and returns to the ocean for fattening after spawning. It is often used for food and has high nutritional value and therapeutic effects.

In the breeding of salmon in running water, the bait is completely fed by hand. It is best to make these baits into particles of suitable size and scientific formula, and the particle size of the bait should be adapted to the size of the fish. The feed ratio is mainly animal feed, including: fish meal, fermented blood meal, meat and bone meal, meat meal, yeast, animal offal, etc.; supplemented by plant feed, including: soybean meal, soybean meal, wheat bran, wheat flour, corn meal, grass meal, etc. In the fry stage, the diameter of the bait should be controlled at 0.5 mm; in the fry stage, the diameter of the bait is about 3-4 mm; in the adult fish stage, the diameter of the bait can be increased to 8 mm.

When feeding, we should prevent the fish from being overfed or underfed. At the same time, we should also flexibly control the feeding amount according to the weather changes, water temperature in the pond, water quality changes, the size of the fish, and the feeding conditions of the fish on that day to prevent water pollution caused by overfeeding.

Fish feed is generally prepared by mixing rice bran, bran, bean cake, fish meal, barley, yeast powder, straw powder, corn flour, sweet potato vine powder, green fodder and other ingredients. Different flavors of fish feed need to be prepared according to different fish species. Common fish feed formula: bran, fish meal, bean cake, barley, green fodder. The main raw materials of fish feed are imported fish meal, soybean grains, crude fiber, vitamins, corn, etc.



Fish bait can be earthworms, raw fat cubes, leeches, dough, fish eyes, fish intestines, rice grains, river shrimps, meat maggots, cornworms, chewing bubble gum, water earthworms, grasshoppers, small fish, and chicken intestines as bait.

No, after all, it is for fish to eat, so people should try not to take it.

No, after all, it is for fish to eat, so people should try not to take it.

What are the main problems facing the water environment of inland fisheries in my country at present? What effective countermeasures should be taken?

Main problems facing the ecological environment of my country's fishery waters

Environmental pollution has caused a serious decline in the quality of my country's aquatic products. Monitoring results show that some shellfish products in my country contain toxic substances such as petroleum hydrocarbons, arsenic, cadmium, and mercury; aquatic products caught near the coast, in inner bays, estuaries, and inland farmed aquatic products are contaminated by heavy metals such as polycyclic aromatic hydrocarbons, mercury, and cadmium. The imminent outbreak of red tides has led to frequent occurrences of paralytic shellfish poisoning and diarrhoeal shellfish poisoning in some areas. In 2001, my country's shellfish, shrimp and other aquatic products were rejected by the European Union and other countries due to substandard toxin and drug residue indicators, causing great losses to my country's aquatic product trade and also had a bad impact on the reputation of my country's aquatic products in the international market.

Affected by environmental pollution and engineering development and construction projects such as reclamation, land reclamation, damming, and sand extraction, many excellent spawning grounds, seedling grounds, fattening grounds, and breeding grounds have lost their fishery functions, the fishery ecological environment has been severely damaged, the proliferation and recovery capacity of fishery resources has declined, and the main economic aquatic biological resources have declined to varying degrees. The types of fish caught in important fishing areas are becoming increasingly single, and the catches are gradually evolving towards younger, smaller, and lower quality. The resources of most traditional high-quality fish species have declined significantly, making it difficult to form a fishing season. As my country's most important fishery production base, the Bohai Sea had an average unit net production of 221 to 43 kg/net/hour in 1959, and the output of major economic fish species reached 138.8 kg/net/hour. By 1998, the output had dropped by nearly 90%, and the output of the main species of fish was 11.18 kg/net/hour. In the 1950s and 1960s, the catch in the East China Sea was mainly high-quality bottom fish, and high-quality fish accounted for 48.3% and 55.4% of the total output, respectively. By the 1980s, the proportion of high-quality fish had dropped to 30.4%. The annual production of the four major carps in the Yangtze River has dropped from 20 billion in the 1970s to more than 1 billion at present. The spawning grounds of the four major carps have almost disappeared due to pollution and environmental changes. The spawning grounds of shad have also ceased to exist. The resources of many rare fish have been greatly reduced. (V) Biodiversity has been destroyed, seriously endangering the material basis for the survival and development of the fishery industry. The pollution of the habitat environment of aquatic biological resources has led to changes in the composition and structure of aquatic organisms, which are specifically manifested in the continuous decline of economic animal and plant resources, the single structure of aquatic biological populations, and the serious destruction of aquatic biodiversity to varying degrees. Monitoring data show that the number of rare and endangered species of aquatic animals in my country has increased year by year, important economic fish such as large yellow croaker and croaker have seriously declined, and the resources of the three major hairy clam farms in the Bohai Sea are close to exhaustion. In inland waters, the number of aquatic wildlife species and the amount of resources are also on the decline. Some rare species are on the verge of extinction. The Baiji dolphin, known as the "Goddess of the Yangtze River", is now less than 100, and precious economic fish such as the Yangtze River white sturgeon, shad, and Songhua River whitefish are hard to find. The latest data shows that almost all aquatic mammals and a considerable number of aquatic amphibians are endangered. There are currently 92 endangered species of freshwater fish, accounting for 10% of the total number of freshwater fish. These endangered fish mainly include 52 species of carp, 11 species of catfish, 5 species of sturgeon, 6 species of salmon and trout, and 18 other species (including eels). Aquatic biodiversity is the material basis for the survival and development of the fishery industry. The decline in biodiversity will shake the material basis for the development of the fishery industry.

The pollution faced by fishery waters mainly comes from the following three aspects:

First, urban life pollution and industrial pollution

With the gradual implementation of the economic development strategy, new cities are rapidly formed in the surrounding areas. A large amount of domestic sewage is discharged every year, and the urban sewage treatment capacity is limited. In addition, the processes used by most sewage treatment plants cannot meet the requirements of phosphorus removal and nitrogen removal, causing offshore pollution. The amount of sewage discharged from washing vegetables, washing clothes, flushing toilets, etc. in life is gradually increasing, causing the pollution of the water environment of the drawdown zone by domestic water to gradually increase. In order to achieve the rapid economic development of the drawdown zone area of ​​the reservoir area, it is necessary to accelerate the construction of infrastructure for domestic sewage treatment in the drawdown zone area of ​​the reservoir area and reduce the discharge of pollutants. The formation of the drawdown zone is due to the seasonal fluctuation of the reservoir water level, which will cause many negative effects on the soil in the drawdown zone area. It is mainly because the pollutants in the reservoir water are continuously enriched in the soil through a series of physical and chemical changes. This will affect the physiological properties of the soil. When the soil is flooded, the nutrients and pollutants in the soil will be dissolved and adsorbed in the water body. It is a complex process.

According to the State Oceanic Administration's 2006 China Marine Environmental Quality Bulletin, the Bohai Sea was seriously polluted in 2006, with an area of ​​about 20,000 km2 that did not meet the clean sea water quality standards, accounting for 26% of the total area of ​​the Bohai Sea. Marine pollution mainly comes from land-based sewage discharge and artificial aquaculture. In 2006, the areas of seriously polluted, moderately polluted, slightly polluted and relatively clean sea areas in the Bohai Sea were about 2,770, 1,750, 7,370 and 8,190 km2, respectively. The areas of seriously polluted and slightly polluted sea areas increased by about 1,000 km2 compared with 2005. Compared with 2002, the areas of slightly polluted, moderately polluted and severely polluted in the Bohai Sea increased by 5,230, 1,290 and 1,760 km2, respectively, an increase of 2.4 times, 2.8 times and 1.7 times, respectively.

Due to the long coastline, many rivers flowing into the sea, rapid industrial development along the rivers, weak environmental protection awareness in some places, incomplete sewage treatment facilities and centralized sewage treatment sites, pollution accidents caused by upstream industrial and domestic pollutants to the marine environment occur frequently. In particular, the land-based pollution caused by rivers at the junctions of counties and provinces is very prominent.

Due to the massive discharge of land-based pollutants, the ecological environment of fishery waters has deteriorated. According to relevant data, the seawater quality of about 206,000 km2 of offshore waters exceeds the first-class seawater quality standard, and its area has expanded by nearly 100% compared with the early 1990s. The area of ​​waters that meet the second-class seawater quality standard is 102,000 km2, the area of ​​waters that meet the third-class seawater quality standard is 54,000 km2, and the area of ​​waters that meet the fourth-class and super-four-class seawater quality standards is 50,000 km2. Inland, the total amount of sewage received by 22 cities along the Yangtze River in the mid-1970s was 14.365 million tons per day, and it soared to 40 million tons in 1996. According to statistics, there are more than 10,000 pollution sources in the entire Yangtze River basin, and 12.2 billion tons of wastewater are discharged into the river every year. The annual sewage reception of the Yellow River was 1.85 billion tons in the 1970s, which increased to 2.17 billion tons in the 1980s and soared to 3.26 billion tons in the 1990s. At present, 82% of rivers and lakes in the country are polluted to varying degrees. The water quality of rivers flowing through cities and lakes in urban areas and suburbs is even worse. According to the figures recently released by the Ministry of Environmental Protection: the total daily sewage discharge in the country has reached 130 million tons, more than 80% of which is directly discharged into rivers, lakes and reservoirs without any treatment, and 78% of rivers flowing through cities have been polluted. Environmental pollution has caused the spawning grounds, feeding and fattening grounds and fishing grounds of some important economic fish to be polluted.

Chemical plants, pesticide plants, paper mills, and industrial wastewater discharge are important factors causing marine pollution. The most important pollution is lead and cadmium pollution. It mainly comes from industrial wastewater and waste residue. Lead can degrade soil fertilizer efficiency and reduce soil quality, thus preventing crops from growing effectively and smoothly. In addition, after being absorbed by crops, these harmful elements will be transmitted to the human body through the food chain in the ecological balance. Cadmium has the characteristics of stable accumulation and difficulty in elimination in the environment. It is enriched through the food chain and causes chronic poisoning in the human body. Cadmium pollution may eventually cause "Itai-itai disease". Studies have reported that the results of evaluating heavy metal pollution status through various methods show that the main pollution factor is cadmium, and the order of ecological risk influencing factors is cadmium>zinc>lead>copper>chromium. The order of potential ecological risk factors is cadmium>zinc>lead>copper>chromium. In addition to the serious threat to fishery resources caused by the oil field drilling platform along the coast, the oil field development has led to the busy trade and transportation of oil products, and also increased the frequency of oil spills in ship accidents.

The occupation of traditional fishing waters by reclamation affects fishery production. At present, the reclamation speed in our province is fast, the area is large, and the scope is wide. There is no detailed reclamation plan, total control, and annual control indicators. The construction of dumping areas for marine projects, with the increase of marine projects, the occupation of dumping areas and the impact of silt caused by dumping on the fishery ecological environment are becoming more and more serious. The impact of the construction period and scrapping period of marine engineering projects such as ports on the fishery ecological environment. At present, the sewage management of marine engineering projects and supporting projects during the use period is relatively standardized, but there are certain problems in the supervision during the construction period and scrapping period of the project.

The second is the pollution caused by the aquaculture industry itself.

Due to the unreasonable development and utilization of marine aquaculture, the local ecological carrying pressure is relatively large, which has a certain impact on the quality of seawater. The direct discharge of aquaculture wastewater has caused a certain increase in the content of nitrogen, phosphorus and other substances in the seawater. Land-based pollutants are the main factor in river pollution, which in turn affects the quality of the marine ecological environment. Therefore, the control of land-based pollution and the solution of river pollution are the key to protecting marine resources and environment. There are 47 major rivers flowing into the sea in our province. Many reservoirs need to be built in the upper reaches of the rivers flowing into the sea due to industrial, agricultural and domestic water use. In addition, the drought in the north in recent years has caused a large amount of water consumption for river irrigation, and the river's own runoff is insufficient.

It is generally believed that the feed coefficient of farmed shrimp is between 1.2 and 1.5, that is, 1.2kg to 1.5kg of compound feed is needed to grow 1kg of shrimp. The conversion and utilization rate of organic matter in feed by shrimp is about 20% calculated by dry matter, and about 80% of the dry matter of feed enters the breeding environment. These substances enter the breeding pond in the form of shrimp excrement and leftover bait. Unlike general farmed fish, since shrimp usually hold and bite feed while swimming, feed particles are very wasteful due to breakage, dissolution and discarding. However, shrimps have short intestines and digest and excrete quickly, so the digestion and absorption rate of feed is also low. Experiments show that only 75% of the feed fed to shrimps is eaten by shrimps, and the rest is lost in the breeding pond in the form of leftover bait (about 15%) and dissolved (about 10%). 5% of the nitrogen in the feed eaten by shrimps is assimilated by shrimps, and 15% is discharged through feces, of which 5% of the nitrogen is directly discharged in the form of ammonia nitrogen and 8% is discharged in the form of organic nitrogen. Every kg of feed consumed by shrimp produces about 0.27 kg (dry weight) of feces, 0.25 kg of suspended particles and 6.12 g of ammonia nitrogen. When studying the metabolic load of solid waste in artificially fed shrimp ponds, Yang Yiping et al. found that 30% of the feed could not be used by shrimp and settled at the bottom of the pond. The shrimp production in my country's coastal areas is 800,000 tons, and the amount of residual bait discharged into the marine environment is also considerable. Some of these organic pollutants are transformed into phytoplankton, protozoa, zooplankton, microorganisms and other organisms and enter the recycling, while some remain in the water and bottom as dissolved and solid substances.

The residual bait and feces produced during the aquaculture process accumulate and decompose on the seabed, increasing the content of organic matter and sulfide in the sediments, and aggravating the pollution problem of aquaculture itself. The sludge in the artificially fed shrimp pond contains 62% to 68% N. The N and P nutrients dissolved from the residual bait are the main sources of pollution for the shrimp aquaculture water environment and its adjacent sea areas. Studies have found that the flux of C and N in the lower sediments of salmon cage aquaculture areas is very small. Only about 10% of organic matter can be decomposed each year, and 79% of C and 88% of N deposition (equivalent to 23% of C and 21% of N in feed input) will accumulate at the bottom and cannot be used by organisms. The organic and inorganic wastes produced by aquaculture can directly cause an increase in the organic load in the bottom sediment of the aquaculture pond and eutrophication, such as increased BOD and hypoxia. Other impacts include acidification of pond soil, reduced biodiversity, increased pathogens, algal blooms, etc., which may eventually lead to the failure of shrimp aquaculture.

Intensive farming achieves high output through high-density centralized feeding and high-intensity feeding. The output of pollutants in the farming process itself mainly includes leftover bait, feces and excrement, etc. These pollutants either cause the water quality of the farming system itself to deteriorate, or pollute coastal waters through the discharge of aquaculture wastewater, and even cause eutrophication. The health of the farming process is as important as the health of the farmed products, which has been widely recognized.

Mariculture destroys the ecological balance of the ocean.

Due to the sharp decline in marine fishery resources, the marine aquaculture industry has developed rapidly. In the past 20 years, the global marine aquaculture output has increased at an annual rate of 10%. The nutrients such as nitrogen and phosphorus contained in the leftover bait and feces during aquaculture, as well as suspended particles and organic matter, will become a source of pollution for eutrophication of water bodies, threatening the survival of fish and shrimp and affecting the marine catch in the Bohai Sea. In addition, intensive net farming adopts high-density stocking, increased use of drugs, and large amounts of exogenous feed, resulting in increased excrement, and a sharp increase in the content of nutrients such as nitrogen and phosphorus and organic matter in the water. Through the study of material balance in intensive shrimp ponds, it was found that only 10% of nitrogen and 7% of phosphorus were absorbed during the farming process, and the rest entered the environment in various forms.

The nitrogen and phosphorus content and oxygen consumption in the bottom mud of the aquaculture area are significantly higher than those in the surrounding water sediments. The accumulation of leftover bait and excrement in the bottom sediment promotes the enhancement of microbial activity and accelerates the regeneration of nutrients. At the same time, the sedimentation and decomposition of dead organisms during the aquaculture process increase the oxygen consumption in the bottom mud, and toxic substances such as hydrogen sulfide and ammonia are produced under anaerobic conditions.

The impact of aquaculture on marine life is also reflected in the impact of escaped fish on nearby marine life. Escaped fish from marine aquaculture may have side effects on the spread of diseases, changes in the genetic composition of wild populations, and may transmit local epidemics to wild populations.

Third, poison invasion plagues the marine aquaculture industry

The invasion of some viruses has also greatly affected the survival of marine life in the Bohai Sea, among which the most typical one is shrimp poison. Since the virus exists in the cells of animals, it is difficult to cure it. In addition, it can spread vertically and horizontally, making many organisms become virus carriers, such as the thick crab and Artemia in Tianjin, which increases the transmission route and is difficult to effectively control, restricting the development of fisheries. It is estimated that if it can be reasonably developed and utilized to reduce the spread of shrimp diseases, it is estimated that the aquatic output of the Bohai Sea will reach 7 million tons in 2010. For example, blindly increasing the breeding density will lead to the occurrence of diseases of breeding species. For example, due to long-term unreasonable high-density breeding and other reasons, in June 1993, a large-scale shrimp plague broke out in coastal aquaculture. The affected breeding area accounted for 76% of the total shrimp breeding area in the country at that time, and the production was reduced by nearly 120,000 tons. The direct economic loss was 3.5 billion yuan, and the indirect economic loss reached 8.6 billion yuan.

Intensify water pollution control, control the quantity of inputs, and protect the ecological environment of aquaculture waters.

Fish cannot live without water. Water is the first element of aquaculture. The quality of water is related to the level of aquaculture output and the quality of aquaculture products. Good water can produce good fish and achieve high yields. According to the current environmental conditions of aquaculture waters, it is necessary to prevent pollution from industrial, agricultural and domestic sewage, and at the same time prevent aquaculture pollution. First, it is necessary to strictly control sewage pollution of aquaculture water bodies. Industrial wastewater and urban domestic sewage must be treated and discharged in compliance with standards to prevent pollution and fish death. Second, it is necessary to use aquaculture inputs scientifically to prevent aquaculture pollution caused by excessive and excessive inputs. Reservoirs that are drinking water sources must be completely banned from input (banning bait, fertilizers, and medicines) to ensure water supply needs and ensure the safety of residents' water use; large lakes and large reservoirs must be banned or partially banned from input. Large lakes must maintain a considerable number of aquatic plants, especially submerged plants, to maintain Class II-III water quality; small and medium-sized lakes and reservoirs must also limit inputs to strictly prevent eutrophication of water bodies and maintain Class III water quality. By banning or limiting fishing, we will do our utmost to protect the environment of lakes and reservoirs, the quality of aquatic products and the ecological balance.

We should strictly control overfishing, protect offshore and shallow-water fishery resources, actively develop offshore and deep-sea fishery resources, and steadily develop offshore fisheries. The development of Bohai Sea fishing should adopt the strategy of "protecting near and fishing far", and adopt the strategy of "guaranteeing the bottom and supplementing the table" in fishing objects and arrangements. At present, the focus of Bohai Sea pollution control is to strengthen the treatment of industrial wastewater directly entering the sea, pollution control in the sea areas adjacent to large and medium-sized cities, and pollution control in river basins entering the sea. The total amount of pollutant emissions and the total amount of major pollutants are determined based on the environmental capacity of the Bohai Sea, as well as the standards for land-based sewage discharge into the sea, and the pollution emission problem is solved through the reasonable planning and use of capacity resources. Therefore, a new fishery environment in the Bohai Sea can be recreated, such as building artificial reefs and planting mangroves. Artificial reefs are artificial structures set up in waters to improve the habitat of aquatic organisms, hinder destructive fishing behaviors, and provide fish and other organisms with places for foraging, reproduction, growth and development, so as to achieve the purpose of protecting and increasing resources and improving the quality of fish catches.

In the past 20 years, many coastal countries have deployed artificial reefs. Among them, in recent years, the national and local governments of Japan have invested about 60 billion yen each year in the construction of artificial reefs, with a construction scale of about 6 million m3. The main purpose of building artificial reefs in the United States is to develop recreational fishing, while the Bohai Sea is to better ensure the quality of Bohai Sea fisheries and the sustainable use of resources. The total amount of pollutant emissions and the total amount of major pollutants and the standards for land-based sewage discharge into the sea are determined based on the environmental capacity of the Bohai Sea, and the pollution emission problem is solved through the reasonable planning and use of capacity resources.

Emphasis on development and protection. The scientific concept of development is used to guide regional economic and social development, ignoring the laws of nature and carrying out predatory development of the natural resources of Honghu wetland. Decision-makers should have a correct understanding of the laws of changes in the lake's ecological environment, abide by the natural laws of the ecosystem, and continuously increase the intensity of lake development while increasing protection efforts.

The protection and governance funds are fully guaranteed. The pollution sources accumulated over the years have not been effectively controlled, resulting in serious degradation of ecological functions. Although rescue protection has been proposed, the resettlement pressure of fishermen and their production and lifestyle have not been effectively improved, and the results of the demolition of fences are facing new challenges. In addition, the investment in ecological restoration and governance funds is seriously insufficient, and the management funds are not guaranteed, so there is a potential rebound threat to the governance results.

The science and technology of ecological environment governance must keep up. Ecosystem governance must address both the symptoms and the root causes, but protection and governance technologies are relatively backward. The current comprehensive governance plans and measures are not scientific and comprehensive enough. Some measures can only address the symptoms but not the root causes, and even have serious side effects. This is mainly manifested in weak scientific and technological strength, lack of scientific research funds, and backward governance measures. Scientific utilization and scientific and technological management urgently need to be strengthened.

There is a lack of effective management and operation mechanism and legal support for water protection and development. Joint development and joint protection are required between upstream and downstream and between regions. At the same time, management departments and local governments form a unified planning scheme on the idea of ​​protection and development, emphasizing collective interests. The water conservancy, environmental protection, agriculture, forestry, fishery, tourism, transportation, land and other departments involved in management each administer according to their own responsibilities and form an effective consultation and communication mechanism.