Growing American paddlefish in aquaculture

American paddlefish is one of the new interesting objects of aquaculture. Sturgeon fish is much easier to grow than regular sturgeon. It is necessary to consider in more detail what kind of fish the American paddlefish is, how to feed it in a pond, where the American paddlefish can be grown and bred, what the fish farmer needs to take into account when choosing a reservoir, methods of growing it, and much more.

Content

• Description of the American paddlefish fish
•  What kind of fish is American paddlefish?
•  American American paddlefish
•  American paddlefish spawning
•  How quickly does a American paddlefish grow in a pond?
•  What do American paddlefish eat?
•  Benefits of raising American paddlefish in aquaculture
•  Advantages of growing American paddlefish in polyculture
•  Dangers of raising American paddlefish in a pond
•  Where can American paddlefish be raised in a pond?
•  Requirements for a pond when growing American paddlefish in a pond and its reproduction
•  Oxygen requirement of the American paddlefish
•  Wintering of American paddlefish
•  Requirements for reservoirs when breeding American paddlefish (broodstock)
•  Artificial breeding of American paddlefish
•  Selection of American paddlefish eggs
•  American paddlefish fertility
•  Artificial fertilization of American paddlefish eggs
•  Incubation of American paddlefish eggs
•  Raising American paddlefish larvae
•  Transportation of American paddlefish larvae

 

Description of the American paddlefish fish

What kind of fish is a American paddlefish?

What kind of fish is American paddlefish? The American paddlefish fish has many names: American paddlefish, American paddlefish, American paddlefish, American paddlefish and many others. The American paddlefish belongs to the American paddlefish family Polyodontidae from the order Sturgeon and includes 2 genera and 2 species.
Where is the American American paddlefish found? American American paddlefish (Polyodon spathula), living in the Mississippi basin (USA) and in other rivers flowing into the Gulf of Mexico.
Where is the Chinese American paddlefish found? Psephur, Chinese American paddlefish (Psephurus gladius) - in the Yangtze basin. Unlike other sturgeons, the American paddlefish has no bugs on its body.

American paddlefish

The American American paddlefish is the most studied. This is a fairly large valuable commercial fish, the length of which reaches 2 m, weight - 83 kg, having a protruding body equipped with a long (up to 1/3 of the total body length) rostrum (nose part), reminiscent of an oar, which is where the name of the fish comes from, and a heterocercal tail. The back is dark gray, the abdomen is light, the mouth is non-protruding, in front of the mouth there are two antennae 3-4 mm long, adults have no teeth, juveniles have many small teeth.
The natural range of the American paddlefish extends over 2 thousand km in the direction from south to north of the United States. American paddlefish fish are adapted to different habitat conditions - from reservoirs in the subtropical south to those located in a sharply continental climate in the north. American paddlefish migrate from rivers to lakes and back, and in the spring - upstream.

American paddlefish Spawning

How do American paddlefish spawn? The reproduction of American paddlefish in natural conditions has been poorly studied. When the water temperature reaches 10-12°C, it begins to migrate to spawning sites - to sections of the river with a strong current and a pebble bottom. Spawning occurs at a depth of 2-12 m at a water temperature of 13-16 C. Female American paddlefish do not spawn annually. In American paddlefish fish, at a water temperature of 14-21 C, embryonic development lasts 170-260 hours. In larvae, the rostrum is absent and begins to grow in fry weighing 0.5-0.7 g.
Puberty occurs depending on climatic conditions: in males - at the age of 6-8, in females - 7-14 years. In the ponds of the Krasnodar region, males mature in the 6th year of life, females in the 11th.
The American paddlefish has pronounced sexual dimorphism. During the prespawning period, the rostrum, head, and sometimes the body of males are covered with a pearly rash and are rough to the touch; The area of the genital opening in females is smoothed and compacted, in males it is surrounded by raised papillae.
We'll talk about how to breed American paddlefish in a pond below.

 

 

How quickly does a American paddlefish grow in a pond?

American paddlefish are large, fast-growing fish. Under natural conditions, rapid growth of juvenile American paddlefish followed by a slowdown was observed. In the first year of life it reaches 25 cm, 2 years - 60, 3 years - 75, 4 years - 100, 12 years - 115, 14 years - 127 cm. At the age of 20 years, a American paddlefish can reach a length of over 2 m. When growing a American paddlefish in the pond it grows very quickly, despite the fact that the growing conditions did not allow the growth potential to be fully revealed.
In American paddlefish, the growth rate in the Krasnodar Territory was the following: the length of American paddlefish underyearlings reached 6-7 cm, the average weight was 670 g, two-year-olds -3.4 kg, five-year-olds -7-8 kg. In favorable conditions, the increase is 6.9 kg in one summer, in less favorable conditions - 3 kg.
The growth rate of American paddlefish in the Moscow region is as follows - the average weight of American paddlefish is: two-year-old - 0.9; three-year-olds - 1.8; four-year-olds - 2.8; five-year plans - 3.3; six-year-olds - 5.5; seven-year-olds - 6.5 kg.
In the conditions of pond farms in Belarus, American paddlefish fingerlings can reach 0.1-0.2 kg, two-year-olds - 1.0-1.5 kg, three-year-olds - 2.5 kg, four-year-olds - 4.1 kg. Without the cost of concentrated feed, the fish productivity of American paddlefish is more than 100 kg/ha.
Thus, the American paddlefish can be recognized as one of the fastest growing pond fish. But as it is easy to notice, with the movement to the north, the growth of American paddlefish when grown in the pond is decreasing.

What does American paddlefish eat?

What to feed American paddlefish? Throughout its life, the American paddlefish feeds on plankton, mainly lower crustaceans, as well as phytoplankton and detritus; cases of predation are also known.
The American paddlefish feeds on plankton as an adult. The rapid growth of the American paddlefish is determined by the American paddlefish's high ability to filter plankton due to the extensive area of the filtration plate, twice as large as that of the bighead carp.
For sustainable growth of American paddlefish, it is necessary that the food supply in the ponds be stable. Favorable feeding conditions that ensure good growth of American paddlefish are considered to be an average seasonal biomass of zooplankton in ponds of at least 15 g/m3. To feed American paddlefish in a pond, the pond can be fertilized, and mineral fertilizers are applied in dissolved form, since American paddlefish are able to filter out undissolved fertilizer particles and swallow them, which can lead to the death of the fish.
Organic matter is also used for fertilizer - semi-rotted manure in an amount of up to 1.2 t/ha per season and dried aquatic vegetation mowed in the pond. Organic matter can be repeatedly added to the pond in small portions. Also, to feed American paddlefish, protococcal algae (genus Scenedesmus and Clorella) and a mother culture of D. magna and D. longispina can be introduced into the pond.

Benefits of raising American paddlefish in aquaculture

There are many positive qualities to raising American paddlefish in a pond, such as:

•  The American paddlefish has a very high growth rate,
•  The American paddlefish has tasty meat, characteristic of the beluga, given that the catch of the latter is prohibited, American paddlefish meat will always be in demand in the market.
•  American paddlefish caviar is close in quality to sterlet caviar, which makes it possible to set up a farm for obtaining American paddlefish caviar; from a female weighing 10 kg you can get 0.5-0.9 kg of caviar, and from a female weighing 18 kg - 1.5-1 .8 kg of American paddlefish caviar.
•  American paddlefish can be grown in ponds, in complex-purpose reservoirs (CPR), including cooling ponds for energy facilities.
•  Cultivation of American paddlefish can easily be incorporated into many polyculture options with other fish.
•  The American paddlefish's nutritional spectrum allows it to be grown at a lower cost than other sturgeons. When raising American paddlefish, you can completely dispense with artificial feed.
•  When grown in the conditions of Belarus, no diseases were observed in American paddlefish fish.
•  breeding American paddlefish in captivity is a complex but possible matter, which can form its own special niche - the production of fish seed material for commercial farms.

Benefits of growing American paddlefish in polyculture

 

Cultivation of American paddlefish in inland waters can be carried out in polyculture with silver carp and carp. So polyculture will allow:
1) carry out biological reclamation of excessively eutrophicated water bodies;
2) eliminate biological interference in the operation of power plants and water treatment plants, as well as other enterprises in whose technological processes water plays a very important role.

Fish farming in such reservoirs can be managed, since neither silver carp and carp, nor American paddlefish find conditions for reproduction in these reservoirs, and the number of their herds is regulated by constant stocking and catching. Therefore, it is recommended to raise American paddlefish in specialized farms, consisting of reservoir reserves for keeping the breeders, a specialized reproduction complex with ponds for keeping the breeders and raising fingerlings, and an incubation shop, which can also be used for the artificial reproduction of other fish species.

Dangers of Raising American paddlefish in a Pond

In its homeland, in the Mississippi basin, the main enemies of American paddlefish are lampreys, as well as the parasite Marsipometra sp. When starting to grow American paddlefish in ponds, you should remember the following:

•  For juvenile American paddlefish weighing up to 500 grams, fish-eating birds (black-headed, little and glaucous gulls) are dangerous, and up to a weight of 2 kg they can be hunted by birds such as herring gull, great cormorant, gray heron, white and black storks, osprey, sea eagle white-tailed, black kite.
•  When raising American paddlefish in a pond, it must be protected from poachers.
•  small semi-aquatic predatory animals, as well as frogs, are dangerous for juveniles.
•  Before introducing American paddlefish into a reservoir, you should pay attention to the presence of three-spined stickleback; its young in the summer can be dangerous for the American paddlefish; they can injure its filtering apparatus, pharynx and anterior parts of the digestive tract, which will negatively affect its growth.
•  Severe blooms of blue-green algae can also pose a danger.
•  If there is a lot of filament in the pond, the fry may become entangled in it. To combat filamentous algae, a suspension of phosphogypsum and a solution of copper sulfate are locally added to ponds.

 

Where can you grow American paddlefish in a pond?

 

The most favorable climatic areas for growing American paddlefish are the North Caucasus; American paddlefish in Ukraine can grown throughout the territory, but the most favorable conditions for American paddlefish are in Ukraine in the south; American paddlefish can be grown in Moldova, that is, territories belonging to fish farming zones V-VI. There are opportunities for growing American paddlefish in Kazakhstan and Central Asia.
In the middle zone, it is advisable to use cooling ponds for breeding American paddlefish. In the conditions of Belarus, American paddlefish were raised in ponds in fish farming zones III and II, which corresponded to the Minsk and Gomel regions.
Breeding material of American paddlefish can be grown in ordinary carp ponds with a good bed layout, ensuring complete drainage, with independent water supply and discharge.
American paddlefish can be grown together with breeding stock of herbivorous fish - black and smallmouth buffalo, black carp, carp and channel catfish. Due to possible competition in nutrition, it is advisable to exclude bighead carp from the polyculture, and if this is not possible, reduce the planting density of both species.

American paddlefish are more demanding on the oxygen regime than carp and herbivorous fish: the oxygen content in water when growing American paddlefish must be at least 5 mg/l.

Wintering of American paddlefish

American paddlefish winter safely in ordinary carp wintering grounds. It is better to winter it separately from other species. When fishing nursery ponds in the fall, it is possible, provided that American paddlefish are constantly selected, to use commercial fish catchers. The American paddlefish is the first to roll into the fish catcher, before the silver carp.

Requirements for reservoirs when breeding American paddlefish (broodstock)

Is it possible for American paddlefish to breed in ponds? The following preliminary requirements for complex-purpose reservoirs (IRP) suitable for raising American paddlefish broodstocks have been determined:

•  reservoir area from 100 to 2000 hectares;
•  the depth of the non-freezing water layer must be at least 1.5 m;
•  absence of pollution of the reservoir by industrial, agricultural and other wastewater;
•  compliance of the hydrochemical regime with environmental quality standards established by fish farming and biological standards for pond farms.
•  To ensure normal growth and development of fish, the average biomass of zooplankton should be at the level of 3-5 g/m3.
•  The area occupied by macrophytes should not exceed 15-20% of the water area.
•  American paddlefish should be reared together with silver carp. The planting density of American paddlefish fingerlings (yearlings) is no more than 50 pcs/ha. To suppress excessive vegetation, grass carp are planted in the reservoir.
•  American paddlefish are easily caught by net fishing gear, so fishing in mother waters should be prohibited.

 

Artificial breeding of American paddlefish

American paddlefish breeding begins with the selection of producers.
In the conditions of the North Caucasus and areas with a similar climate, the following indicators of the average mass of American paddlefish breeding material (in kg) can be recommended: 0+ - 0.1; 1+ -1.5; 2+ - 3.5; 3+ - 5.5; 4+ - 7.5; 5+ - 9; 6+ -10.5; 7+ -11.5; 8+ -13; 9+ -14.5. Starting from age 5+, the growth in males is 50% less than in females.
The yield of American paddlefish should be: fingerlings from grown juveniles (average weight 150 mg) - at least 70%; yearlings from wintering grounds - 80%; two-year-olds - 90%; older age groups - at least 95%.
The assessment of American paddlefish breeders and repairs is carried out annually in the spring (in the Krasnodar Territory in the second half of March - early April). The capture of American paddlefish from wintering ponds is carried out by water using a hamsoros seine. Fish are taken from the seine using fabric sleeves 1.3-1.5 m long, placed on one side on a metal hoop with a diameter of 35-45 cm (when carrying spawners weighing more than 15 kg, sleeves with a larger diameter are used). It is not recommended to carry fish by hand (without sleeves) to avoid injury. Captured breeders are transferred to a stretcher with water, equipped with tarpaulins. fish; stretcher length - at least 1.5 m, width -40-45 cm.
The caught fish is inspected, weighed, and the necessary measurements are taken. Individual indicators that are taken into account during grading and used for further breeding work include sex, age, group, mark (individual or group), the degree of expression of sex characteristics and readiness for spawning, and average weight.
Determination of individual indicators is mandatory for producers and the senior repair group transferred to the broodstock.
There are several marking methods that are quite suitable for American paddlefish: marking with silver nitrate solutions, “soft” thermal branding, cryobranding (with a brand cooled to a low temperature), and special dyes. The simplest and most reliable way is to apply marks by cutting the fins. Hanging tags should not be used when working with American paddlefish, as they are lost during fishing.
In females, a sign of readiness for spawning is the presence of a convex, saggy abdomen, and in males - a nuptial plumage in the form of a pearl rash. Some males are fluid. A biopsy is used to assess the readiness of females for spawning. To do this, with a stainless steel probe (Fig. 56, a) at an acute angle to the surface of the body, a puncture is made in the abdominal cavity to a depth of 6-8 cm and several oocytes are removed (Fig. 56, b). This does not harm the fish, and the wound will heal quickly. The oocytes obtained in this way are immersed in boiling water for 1-2 minutes. The eggs removed from boiling water are cut with a safety razor blade along the animal-vegetative axis. The location of the germinal vesicle (nucleus) determines the degree of maturity. In females ready for spawning (IV stage of maturity), the nucleus, visible even when observed with the naked eye, lies close to the shell. Externally, such eggs have a well-defined animal pole, an elastic shell, and are colored dark gray.

Females with oocytes with a nucleus located in the center are placed in pre-spawning ponds for holding and used for reproduction later, while those with oocytes with signs of degeneration (impaired pigmentation, weak shells, etc.) are not used for work and are sent for feeding.
When selecting males, preference is given to individuals that have a well-defined nuptial plumage and fluid reproductive products. It should be noted that many males have milts with low sperm concentrations, but these can also be used for reproductive purposes. Non-breeding males are used as reserves or planted in summer brood ponds.
Pre-spawning maintenance of American paddlefish spawners is carried out in small, easily fished ponds (area 0.1-0.2 ha, depth 1.5-2 m). Ponds should be well designed, drain quickly and refill quickly. A prerequisite is a good oxygen regime - a drop in oxygen content below 5 mg/l is unacceptable. The planting density of producers is up to 500 pcs/ha.
To maintain spawners after injection, it is advisable to use earthen spawning cages used for herbivorous fish. The area of such cages is 15-20 m2, depth 1-1.5 m. You can also use concrete pools and commercial cages installed in ponds and other bodies of water (cage area - at least 20 m2, depth - 1.5-2 m; pool area -15-20 m2, depth -1.5-2 m). Planting density of producers - 1 specimen. for 4 m2.
Work on artificial breeding of American paddlefish begins when a stable water temperature reaches 13-15°C. To stimulate the maturation of producers, the pituitary glands of sturgeon fish are used. To reduce the intensity of post-injection inflammatory processes, penicillin is used (50 thousand ME per fish). When working with females, a double injection is used: preliminary - 0.9-1 mg/kg of pituitary substance and resolving - 6-8 mg/kg. The interval between injections is 24 hours.
Males are given one injection (3-4 mg/kg) before the permissive injection in females. Injection is carried out in a canvas stretcher or directly in cages or pools, after which females and males are kept separately.

 

Selection of American paddlefish eggs

In American paddlefish, at a water temperature of 14-16°C, females mature in 21-24 hours, at a temperature of 17-19°C, in 18-21 hours. A sharp decrease in temperature negatively affects the course of maturation - it delays ovulation and damages oocytes. When the expected period of maturation occurs, the female is removed from the water. After the fish has calmed down, massage the back of the abdomen. In ripe fish, when lightly pressed, caviar flows out of the genital opening, the quality of which depends on the correct timing of its receipt. It is necessary to choose a state when some of the oocytes have already ovulated and are in the body cavity, and the rest easily slide off the ovary. First, you should take a sample of caviar from the American paddlefish.
The female is wiped with a clean gauze cloth (or towel) and the selection of eggs begins. The first portion of caviar is filtered into a clean enamel basin. By straining, as a rule, it is possible to obtain 50-100 ml of caviar. With further periodic straining, approx. After about an hour, it is possible to get another 2-3 servings of caviar, 50-100 ml each, but the quality of the caviar decreases and a considerable amount still remains in the body cavity.
Considering the special value of the American paddlefish, intravital methods of egg selection should be used. After the first straining, the female is again placed in a cage or pool, then after 30-50 minutes she is caught a second time, subjected to anesthesia, placed on a table and wiped with a gauze cloth. Then, stepping back 1.5-2 cm from the dark strip running along the abdominal part of the body, an incision 8-10 cm long is made. The incision field is pre-treated with an alcohol solution of iodine. After this, the female is turned on her side towards the incision and the eggs are carefully taken into the basin with her hand.
The fish is held by two assistants during the operation. She usually acts calm. After the caviar is collected, the incision is sealed with catgut. Sutures are placed using a surgical needle and needle holder. At the end of the operation, the females are released into the pond. It is impossible to keep operated fish in cages and pools, since the seam and the walls are injured and wound healing occurs much more slowly. Typically, females tolerate the operation well - their survival rate after selection of eggs is at least 80%. The described method was first proposed by VNIRO employee I.A. Burtsny in 1987.
Nowadays they also use the S.B. method. Pillows, which consists of cutting one of the oviducts and straining out the eggs by massaging the abdomen in the direction from head to tail.

American paddlefish fertility

The fertility of females depends on their size and the conditions under which the fish are kept. In females with an average weight of 10 kg, fertility is 60-100 thousand eggs, weighing 18 kg - 170-200 thousand eggs. There are an average of 110 eggs in 1 g of caviar. The diameter of unfertilized eggs is 2.6 (2.2-3) mm.
The females from which the eggs were obtained miss one spawning season, that is, they can be used for new production only after two years.
Milk from males is expressed by light massaging. The semen is mostly watery, the color of serum. Sperm concentration is 0.48-0.8 billion/mm3, less often - 0.9 billion/mm3. Average ejaculate volume is 70 ml. The fertilizing ability of sperm at a water temperature of 14°C is maintained for 5-8 minutes. When stored in the refrigerator, sperm retains its fertilizing ability for more than a day.

Artificial fertilization of American paddlefish eggs

American paddlefish eggs and sperm are collected in dry vessels. Fertilization of eggs is carried out using a semi-dry method. Before fertilization, the cavity fluid is drained from the vessel with the eggs. A mixture of sperm from three males (depending on its quality, from four to 100 ml per 10 liters of water) is poured into a bucket of water, quickly stirred and poured into the caviar. The latter is thoroughly mixed with feathers for 3-5 minutes, after which the water and sperm are drained and the eggs are de-glued.
De-sticking is carried out in AOI devices using a talc suspension (100 g of talc, 9.5 g of table salt per 10 liters of water), as well as other de-sticking agents. A talc suspension is poured into the caviar and, while continuously stirring, the suspension is periodically added. The de-sticking process lasts about 40 minutes. After this, the eggs are washed with clean water and placed in incubators.

Incubation of American paddlefish eggs

Incubation of American paddlefish caviar is carried out in the same apparatus as sturgeon caviar (Sturgeon apparatus, etc.). 100-150 thousand eggs are placed in one apparatus. Avoid exposing the eggs to direct sunlight. The oxygen content during egg incubation should not fall below 6 mg/l. The optimal incubation temperature for American paddlefish eggs is within 14-18°C. At a water temperature of 13°C, embryonic development lasts 260 hours, at 18°C -113 hours.
The fertilization of eggs is determined at the stage of 4 blastomeres (at a temperature of 12°C after 6 hours from the moment of fertilization, at 14°C - after 4 hours, at 18°C - after 3 hours). During the incubation process, preventive treatment is carried out with dyes (malachite green, methylene blue), starting from the 2nd day of incubation - 1-2 times, exposure - 15-20 minutes. Dissolve 150 mg of dye in 60 liters of water.
Caviar can also be treated with formalin at a concentration of 1:500 -1:1000 with an exposure of 15 minutes.
After hatching, free embryos are siphoned from the apparatus and placed in flow-through trays, baths and pools.
Planting density for aging is up to 5 thousand pieces/m2. Depending on the water temperature, 8-10 days after hatching the larvae switch to a mixed diet.

Raising American paddlefish larvae

Ungrown American paddlefish larvae should not be planted in ponds for cultivation - the survival rate is too low.
It is believed that the survival rate of American paddlefish fingerlings when reared in polyculture in production ponds of fish farms from stocking with larvae weighing up to 30 mg is no more than 8.5%; from fry weighing 100–300 mg - about 30%; from fry weighing 600 mg - no less than 60%. Therefore, rearing of American paddlefish larvae is required.
American paddlefish larvae are reared in flow-through baths, pools, and trays. Planting density at the beginning of growing - 5 thousand pcs./m2, by the end - 2 thousand pieces/m2. Regularly selecting dead larvae, the juveniles are sorted by size (American paddlefish, like other sturgeons, exhibit cannibalism). For American paddlefish, the optimal temperature for growing larvae is 20-22°C. During the growing period, the larvae are fed with zooplankton, brine shrimp, etc. American paddlefish larvae prefer large forms of zooplankton. The availability of organisms is directly dependent on the size of the mouth opening. The larvae are grown over 10-15 days to a weight of 150 mg, maintaining the zooplankton concentration at 3-5 mg/l all this time. You can raise American paddlefish larvae on starter feeds used for other fish species, but when choosing one or another feed, you should take into account that American paddlefish eat food while it is in suspension and are reluctant to take food from the bottom.
To obtain American paddlefish larvae of greater mass, they are raised in pools for longer than 20 - 30 days, and fry weighing from 0.4 to 1.3 grams is obtained (the weight depended on the density of the larvae, the optimal density of American paddlefish larvae in the pools is 1.25 thousand pieces per 1 m2).

Transporting American paddlefish larvae

The larvae are transported in plastic bags with water and oxygen. The stocking density of ungrown larvae (weighing 10-15 mg) with a transportation duration of up to 24 hours is no more than 15 thousand pieces, juveniles weighing 100-150 mg - 400-500 pieces each. per package.
Commercial American paddlefish are transported at a water temperature of no higher than 15°C. The duration of detention in a canvas stretcher is no more than 5 minutes, transportation is up to 20-25 minutes (the latter is carried out in canvas vats). Up to 100 kg of fish are placed in 1-1.5 m3 of water. Transportation lasting up to 1.5-2 hours is carried out in live fish tankers with constant water aeration, transporting up to 120 kg of fish in one trip.