The article presents the results of approbation of the artificial nest-incubator of eggs "Salmo-3000" for the reproduction of salmon species of fish of the genus Salmo, tests were carried out in the r. Inder (White Seabasin). An original device was used, installed at the bottom of the river's threshold section. The nest design includes: the main body - a streamlined oval flattened container formed by three layered incubation trays and a lid; remote water intake / filter; connecting branch pipe with accessories for water distribution and discharge; elements fastening to the ground and a device for driving fasteners into the ground. The nest allows you to incubate fertilized eggs of Atlantic salmon or brown trout during autumn, winter and spring (autonomy for at least 8 months) and in summer (June) to obtain viable larvae that independently settle in the river threshold or are forcibly removed from rearing devices in the basins. During the test, the following advantages were revealed (increased capacity for incubated eggs up to 3,000 salmon / brown trout eggs per device, effective water distributor, grates that limit the eggs from washing out during laying, fixing rods made of fiberglass reinforcement that do not give oxidation, water intake / filter effectively cleaning and supplying water to caviar), and the disadvantage - the complexity and duration of the installation of the device, up to 60 minutes per device. In general, the hatching efficiency of larvae was 97.2% at partial load. The output of fry into the river was 96.0%. The device can be used to restore the abundance of Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.) in small rivers where hatchery reproduction is unprofitable for various reasons.

The result of an extra factory method of reproduction of a chum (Oncorhynchus keta) is presented. The method is tested in small tributaries river Mulka (bass. The Sea of Okhotsk, Strait of Tartary) and in Savushkin's river (bass. Sea of Okhotsk, Second Kuril passage). The original devices representing the flattened container in which in 6 tiers incubatory modules with flutes for caviar are placed are used. The nest allows to incubate during the winter the impregnated caviar of salmon species of fish and to receive the durable larvae which are independently settled in a threshold of the river or forcibly taken from devices in pools in the spring. The device has the increased capacity for the incubated caviar to 10000 berries of a chum on the device, the volume method of loading of caviar in the device is applied, time of equipment and installation of a nest to the river doesn't exceed 15 minutes. In general efficiency of hatching of larvae has made 96%. An exit of larvae has averaged 42,5%. At insignificant completion the device can be used for restoration of number of a chum and other salmon species of fish in the small rivers where factory reproduction is for various reasons unprofitable.

The outcome of a non-hatchery method for chum salmon (Oncorhynchus keta) reproduction is presented. The method was tested in small tributaries to Malka River (Sea of Okhotsk catchment, Tatar Strait). Specially designed incubation nests were deployed on the bottom of river stretches with rapids. Each device is a streamlined flattened vessel with two layers of incubation plates with wells for individual egg. There is a water inlet in the bottom of the device to secure continuous supply of fresh water; water with embryos’ waste products is washed out of the device through an outlet tube on the top. The nest allows incubating fertilized chum salmon eggs during the winter and get viable larvae in spring, who would then either disperse across the rapid by themselves or be taken out of the devices to be post-reared in pools. The trial revealed both strengths(higher capacity for the incubated eggs –up to 404 chum salmon eggs per device, slots in the bottom of the wells preventing eggs from falling through to the underlying collection chamber during incubation but at the same time allowing the movement of larvae to the collection chamber after hatching) and structural flaws (poor water flow in the cassette installation mode, as well as flow blockage by sand clogging the water intake pipe). Overall, the hatching rate was 97.8 %. Not more than 48.7 % exited the next as larvae. Mortalities were partially due to the blockage of flow through the devices as a result of a critical drop in the water level during the winter low water period, and to the high sediment load, up to 25 cm. Losses were higher, in some devices up to 100 %, in the nests with cassette-type installation. After a minor upgrade, the device can be used to restore the numbers of chum salmon and other Pacific salmon species in small rivers.

We experimentally studied the locomotor components of rheotactic response in three age cohorts (0+, 1+, 2+) of Altantic salmon and brown trout parr from, respectively, the Varzuga River main channel and tributary (Kola Peninsula, White Sea drainage basin). A specially designed hydrodynamic device permitting to regulate the current velocity from 0.05 to 0.9 m/s was used. There was no reliable difference between velocity thresholds for 0+ salmon and brown trout or for 1+ parr of the two species. For 1+ parr, however, the velocity threshold was lower than for 0+ parr in both species. Sensitivity to the current dropped sharply in 2+ parr, especially in brown trout. In brown trout aged 1+ and 2+, theindex of active rheotactic response, meaning that locomotion is activated to keep the position in the current, is reliably higher than in salmon. The critical rheotactic response index also differed among age cohorts, and brown trout parr excelled, withstanding current velocities of 80–90 m/s for several seconds. Differences in rheotactic response indexes apparently ensue from the hydrological, thermal and trophic conditions of habitats in the main channel and the tributary, which influenced the size and weight of parr in both species. The main channel is mostly inhabited by salmon parr, whereas the tributary is hometo brown trout parr, which grow faster owing to the better foraging conditions.

The outcome of a trial application of a non-hatchery method for the reproduction of brown trout, Salmo trutta L., in the Ulmosenjoki River (Lake Ladoga catchment) is presented. Specially designed incubation nests were planted on the bottom of a rapid section of the river. Each device is a streamlined flattened vessel with two layers of incubation plates with egg slots inside it. There is a water inlet in the bottom of the device to secure continuous supply of fresh water to the eggs; short tubes through which larvae can leave the nest are situated laterally. The nest allows for incubating impregnated brown trout eggs through the winter, yielding in spring viable larvae, which will then disperse around the rapid. The trials revealed both advantages (increased capacity for the incubated eggs) and structural shortcomings (poor flow at the lower incubation plate, hindering the exit of larvae). Overall, the nest’s hatching yield was 92–5 %, but no more than 70 % of the larvae exited the nest. Given a minor upgrade, the device can be used for restoration of brown trout stock in small rivers, where hatchery-based reproduction is for various reasons impractical.

There has been developed and approved new design for the artificial redd aimed for the incubation of fertilized eggs and development of larvae of Atlantic salmon under river conditions. A trial conducted in the River Indera (Kola Peninsula) in 2007 has shown that such artificial redds can be used for the intensive population of vacant rapids and rifts in salmon rivers. The efficiency of hatching and fry emergence calculated as a ratio between laid and lost eggs was 81-97%. ______________________________________________________________________________________