The results of the investigations on fat of the Atlantic herring Clupea harengus carried out in the BaltNIIRKH (Latvia) are presented. Data on the peroxide content in fat of salted Atlantic herring classified to various sorts based on the character of fat oxidation are given. | Published | Not Known

A method for increasing of the growth rate and the viability of salmon Salmo salar fry is described. The enrichment of the artificial feed with biologically active growth stimulators - the trace elements and the substances containing antibacterial compounds and phytoncides, is considered. The results of the experiments on the rearing of the 0-group salmon with different feeds are presented. The investigation allows a more precise definition of the ingredients in the artificial feed KRT that is used for salmon rearing in Latvia. | Published | Not Known

The methods of rearing of young North-Caspian (Acipenser gueldenstaedti Brandt) and Baikal (Acipenser baeri stenorrhynchus natio baicalensis A. Nikolski) sturgeons in the fish hatchery "Karli" (Latvia) are described. Data on the temperature regime of water during the rearing and on the changes in the weight and length of fish are reported. The feeding regime, ration and the technique of the artificial feeding are discussed. The results of the study showed that rearing of 5-8-gram young North-Caspian and Baikal sturgeons at high densities is possible on the feed mixture KRT-6 and stuffed spleen. | Published | Not Known

The results of the investigations on the smoltification conditions of salmon Salmo salar and sea trout Salmo trutta and the dynamics of their natural descent to the Baltic sea are described. Also, some smolt's features were studied. Applying the method of tagging and recaptures, the total salmon stock at the age of 1-4 years in the Salaca River (Latvia) was estimated at about 8500 specimen in 1964 and 9600 individuals in 1965. Both in 1964 and 1965 the 2-year-old fish were in majority. The increase in their number in 1965 can be explained with better feeding conditions in the season before the descent to the sea, as well as with favourable smoltification and migration conditions. | Published | Not Known

Salmon Salmo salar and lamprey Lampetra fluviatilis belong to important food fish in Latvia. For the investigations on the spawning migrations of salmon and lamprey the daily catches of these species in the rivers and their correspondence to the chief hydro-meteorological factors - the oscillation of water level in the lower reaches of the river, phases of the moon, and the hydrological background, were analysed. It was established that the daily catches mainly depended on the water level at the mouth of the river. The catches less depended on the phases of the moon and the hydrological background. In addition to the changes in the water level, the absolute height of water was important. In the case the water in the lower reaches of the river was lower of a critical level, the salmon and lamprey catches were absent. The above regularities could be applied for the composition of short-term forecasts (2-3 days in advance) on salmon and lamprey catches, if the prognoses on the water level in the river for a longer period were available. | Published | Not Known