CATDOLL : CATDOLL: The best time to fish for dace in spring

1. The best time to fish for dace in spring

Fishing should be done when the water temperature is highest each day.

The climate change in spring is more obvious, and we can also see it from the temperature difference between morning and evening. Therefore, if you want to catch earth carp in the spring, in addition to finding the fish layer, you need to grasp the golden fishing time every day. In layman's terms, it is to find out when the water temperature is higher that day. Generally speaking, in clear weather, 10 am to 13 pm and 15 pm to 16:30 pm are the golden time periods for fishing earth carp. Why do you say that? Strictly speaking, if you want earth carp to bite, the water temperature needs to reach above 14 degrees Celsius. So, we need to understand that although the sun comes out very early in spring, it takes a certain amount of time for the water temperature to rise in natural waters. Liangzi usually starts to bite around 10 o'clock when fishing in the spring. This also needs to be determined according to the current actual situation.

2. Hybrid breeding

2. Hybridization method After the parents are determined, the hybridization combination method used is also related to the success or failure of breeding. Commonly used hybridization methods include single hybridization, composite hybridization, backcrossing, etc.

1) Single cross is the hybridization (single cross) between two varieties, represented by A×B, and its hybrid offspring is called single cross. Because it is simple, easy and economical, it is the most widely used in production. Generally, the first generation of hybrids is used, such as Fengli and Fushouyu.

2) Composite hybridization is a breeding method that uses more than two varieties and crosses them more than twice. If single cross cannot achieve the expected trait requirements of breeding, composite hybridization is often used. Its purpose is to create some hybrid original groups with a rich genetic basis, so that better individuals can be selected from them. Composite hybridization can be divided into three-way cross, double cross, etc. Three-way cross is a hybrid of a single cross species and another variety, which can be expressed as (A×B)×C, such as (purse red carp×Yuanjiang carp)×scattered scale mirror carp-three-way hybrid carp. Double cross is a hybrid of two different single cross species, which can be expressed as (A×B)×(C×D) or (A×C)×(B×C), such as (blue carp×Nile carp)×(Mozambique carp×Nile carp).

3) Backcrossing is a breeding method in which the hybrid offspring is further hybridized with one of its parents to strengthen the characteristics of a parent in the hybrid generation. When the purpose of breeding is to introduce one or several economic characteristics of a group B into another group A, backcrossing breeding can be used. For example, dace has many excellent characteristics, but cannot tolerate low temperatures and needs genetic improvement. You can first hybridize the low-temperature tolerant Xianghua dace with dace, and then backcross the hybrid offspring with dace. The backcross offspring continue to be backcrossed with dace for multiple times. The selection of backcross offspring must focus on the target trait of cold resistance, so as to eventually breed a new variety of cold-resistant and excellent dace. 1) Preparation before hybridization First of all, you must be familiar with the reproductive habits of various fish. On the one hand, we need to understand the sexual maturity season, reproductive season, egg properties, sexual cycle, spawning period, protection of eggs and offspring and other habits of fish related to reproduction; on the other hand, we need to understand the requirements of fish for external conditions during the reproductive period, such as water temperature, light, flow rate, bottom quality of spawning grounds, fish nests, feed, etc. Secondly, we need to adjust the sexual maturity age of the parents, and ensure that the parents to be hybridized meet in the reproductive season by means of staged feeding and creating different external conditions.

2) Choose an appropriate fertilization method for hybridization. In the early stage of hybridization, when sexual maturity and the reproductive season are approaching, male and female fish must be kept in separate ponds to avoid self-mating. The fertilization method is determined according to the specific situation. Natural spawning and fertilization are generally used for hybridization between species. Artificial insemination is used when natural reproduction and hybridization are not possible (see Chapter 4 for specific operation methods).

3) Recording, labeling and management When hybridizing fish of different varieties (or species), records must be kept. The records include parental traits and related information, hybridization method, hybridization time, survival rate of each period, etc., for reference. After the fry are put into the pond, the test pond must be labeled and registered, indicating the fertilization date and the names of the parents. Management should be strengthened during the breeding period, and special attention should be paid to avoid mixing between different hybrids. If hybrids are accidentally exiled to natural waters such as rivers and lakes, it will cause irreversible serious consequences such as genetic mixing of natural populations, affecting the effective use of natural resources.

4) Accelerate the breeding process. It often takes 10 generations from hybridization to the breeding and promotion of new varieties, so it is necessary to accelerate the breeding process. You can use off-site generation, such as establishing a fish breeding base in Hainan Island, breeding in the north and raising in the south, to shorten the breeding time. You can also use greenhouses and artificial climate chambers to increase the generation. When the scale of the breeding base required is not large, this method can accelerate the breeding process.

5) When the individual selection method is used for the selection of hybrid offspring, the selection generally starts from the second generation, because the second generation has the largest variation range, and it is expected that a suitable variant can be selected from it. By the third generation, it is basically possible to determine whether there is hope of breeding a variety. By the fifth generation, most traits and families are quite stable, and the variety can be determined at this time. When the group selection method is used, generally no individual selection is performed before the fifth generation, only group selection and mixed breeding are performed. Individual selection begins from the fifth to the eighth generation to establish the family and determine the variety.

1. Application conditions: When the traits of the two parents basically meet the breeding goals and their advantages and disadvantages can complement each other, single cross can be used. When the breeding goals are higher than the requirements, and the single cross offspring cannot meet them; or when one parent has very outstanding advantages but also obvious disadvantages, and one hybridization cannot overcome the disadvantages, multiple cross can be used.

2. Trait separation generation: Since at least one of the parents of the polyhybrid is a hybrid, trait separation will occur in the polyhybrid F1.

3. Breeding process: Multiple cross breeding can provide more types of variation than single cross breeding, but its genetic basis is more complex, the traits stabilize more slowly, and the breeding period required is longer.

4. Hybridization workload: Since the multiple cross separation generation appears in F1, and F1 seeds are obtained by artificial hybridization, if you want to obtain a segregated population of single cross F2, the hybridization workload will be dozens of times greater.

III. Regulations on the Protection of Aquatic Resources

Chapter I General Provisions Article 1 In accordance with Article 6 of the Constitution of the People's Republic of China, which states: "Mineral deposits, watercourses, state-owned forests, wastelands and other marine and terrestrial resources are owned by the whole people" and Article 11, which states: "The state protects the environment and natural resources and prevents pollution and other public hazards", these Regulations are formulated in order to breed and protect aquatic resources, develop the aquatic industry and meet the needs of modernization. Article 2 All parents, larvae, eggs, spores, etc. of aquatic animals and plants of economic value, as well as the water environment on which they breed and grow, shall be protected in accordance with the provisions of these Regulations. Article 3 The State Fisheries Administration, the fishery headquarters of each sea area and the revolutionary committees at all levels in the localities shall strengthen the organizational leadership of the breeding and protection of aquatic resources, fully mobilize and rely on the masses, and conscientiously implement these Regulations. Chapter II Objects of Protection and Principles of Harvesting Article 4 The following important or precious aquatic animals and plants shall be given priority protection.

1. Fish

Marine fish: hairtail, large yellow croaker, small yellow croaker, blue sea cucumber, sardines, Pacific herring, herring, red sea bream, black sea bream, two-spined sea bream, red snapper, pike, flounder, plaice, sole, stone grouper, cod, dogfish, golden threadfish, pomfret, anchovy, white croaker, yellow croaker, mackerel, mackerel, mackerel, and conger eel.

Freshwater fish: carp, black carp, grass carp, silver carp, sturgeon, redfin sturgeon, dace, crucian carp, shad, mandarin fish, bream, bream, salmon, Yangtze sturgeon, Chinese sturgeon, white sturgeon, naked carp of Qinghai Lake, anchovy, whitebait, river eel, yellow eel, and carp.

2. Shrimp and crab

Prawns, hair shrimps, green shrimps, hawk claw shrimps, Chinese mitten crabs, swimming crabs, and blue crabs.

3. Shellfish

Abalone, razor clams, cockles, oysters, clams, scallops, river clams, clams, variegated clams, green mussels, purple mussels, thick-shell mussels, pearl oysters, and river clams.

4. Seaweed

Nori, kelp, agar, seaweed, kelp, and Eucheuma.

(V) Freshwater edible aquatic plants

Lotus root, water chestnut, and water caltrop.

(VI) Others

White-fin dolphin, whale, giant salamander, sea turtle, hawksbill turtle, sea cucumber, squid, cuttlefish, turtle, and soft-shell turtle.

The revolutionary committees of provinces, autonomous regions and municipalities directly under the Central Government may make necessary additions and reductions to the key protected objects according to the local aquatic resources. Article 5 The catchable standard of aquatic animals shall be based on the principle of sexual maturity. Specific catchable standards (length or weight) and the maximum proportion of the part of the catch that is smaller than the catchable standard shall be stipulated for various fishing objects. When fishing, a sufficient number of broodstock shall be retained to ensure that the resources can grow steadily.

All kinds of economic algae and freshwater edible aquatic plants should be harvested after they grow up, and attention should be paid to retaining seeds and plants, and reasonable rotation should be taken. Article 6 All localities should adopt various measures according to local conditions, such as improving water conditions, artificially releasing seedlings, releasing fish nests, flooding rivers with seedlings, rescuing young fish, transplanting and domesticating, eliminating enemies, introducing and planting, etc., to increase aquatic resources. Chapter III Prohibited fishing areas and fishing periods Article 7 For certain important spawning grounds, wintering grounds and juvenile feeding grounds of fish, shrimps and shellfish, reasonable prohibited fishing areas and fishing periods should be stipulated, and all operations should be prohibited, or the types of operations and the number of fishing gears for certain operations should be restricted according to different situations. Article 8 All rivers that are spawning and migratory channels for fish, crabs, etc. shall not be blocked for fishing, and a certain width of channel shall be left to ensure that a sufficient number of parents go upstream or downstream to spawn and reproduce. It is even more forbidden to intercept fish and crab larvae and spawning and migratory parents at the gates, and a fishing period should be stipulated when necessary. Those who catch fish fry and crab fry for aquaculture production needs must obtain approval from the fishery departments of provinces, autonomous regions, and municipalities directly under the Central Government and operate in designated waters and within designated time periods. Chapter IV Fishing Gear and Fishing Laws Article 9 The minimum mesh (foil) size of various major fishing gears shall be specified according to different fishing targets. The minimum mesh size of motor wheel trawl, purse seine and motor sail trawl shall be specified by the State Fisheries Administration.

It is prohibited to manufacture or sell fishing gear that does not meet the regulations. Article 10 Existing fishing gear and fishing methods that are harmful to resources should be treated differently according to the degree of their harm to resources. Those that are less harmful to resources should be improved in a planned and step-by-step manner. Those that are seriously harmful to resources should be prohibited or eliminated within a time limit. Before they are completely eliminated, their operating locations and time should be appropriately restricted.

Small-mesh nets for catching small mature fish and shrimp are only allowed to be used in designated waters and at designated times. Article 11 It is strictly prohibited to use explosives, poison fish, abuse electricity to catch fish, and conduct knocking (zhougu) operations and other acts that seriously damage aquatic resources. Chapter V: Maintenance of the Water Environment Article 12 It is prohibited to discharge pollutants and wastes such as sewage, oil, and oily mixtures that are harmful to aquatic resources into fishery waters. All industrial and mining enterprises must strictly implement the "Trial Standards for the Emission of Industrial "Three Wastes", "Radiation Protection Regulations" and other relevant regulations issued by the state.

When it is necessary to inject drugs into fishery waters for sanitation and epidemic prevention or to eliminate pests and diseases, the reproduction and protection of aquatic resources should be taken into consideration. Rural immersion should be concentrated in designated waters. Article 13 When constructing water conservancy projects, attention should be paid to protecting the environment of fishery waters. When dams are built in the migratory channels of fish and crabs, fish-passing facilities should be built accordingly. For completed water conservancy projects that hinder the migration and spawning of fish and crabs, the fishery department and the water conservancy management department shall consult and open the gates to admit fish or capture fish for transplantation in a timely manner under the conditions of permitted water level, water volume and water quality.

Reclamation of tidal flats and lake beaches must be carried out in a planned and coordinated manner without damaging aquatic resources.