K. A. Savvaitova

Variations of life history strategy of the arctic lamprey Lethenteron camtschaticum from the Utkholok River (Western Kamchatka)

Morphobiological traits of the lamprey from the Utkholok River (Western Kamchatka) are investigated for the first time. All present forms of lamprey (typically anadromous, anadromous early maturing forma praecox, resident) do not differ by diagnostic characters and belong to one species Lethenteron camtschaticum. Males prevail among mature specimens of various forms, smolts, and ammocoetes at later developmental stages. The forma praecox is represented by males by 92%. A hypothesis is suggested explaining the relationships of the forms and the mechanism of realization of different types of life history strategy in relation to energy resources of water bodies and the kind of feeding of different groups of ammocoetes (organic detritus or Pacific salmon carcasses decomposed after spawning).

On the problem of ratio of anadromy and residence in salmonids (Salmonidae)

According to published and original data, the anadromy and residence in salmonids (Salmonidae) are considered: within one population; in males and females; in different populations in the area of one species under natural conditions; outside of the natural area, at introduction; types of anadromy and residence in different species; causes and mechanisms of formation of anadromous and resident strategies; and applied consequences in the light of notions on formation of life strategies.

Diversity of life strategies and population structure of Kamchatka mykiss Parasalmo mykiss in the ecosystems of small salmon rivers of various types

The diversity of life strategies and population structure of Kamchatka mykiss Parasalmo mykiss in the ecosystems of small salmon rivers of various types are considered. Hydrogeomorphological differences of the model rivers Kol and Kekhta are found. The preferred habitats are investigated, and their area is determined. It is shown that, in the Kol River, the mykiss having a resident life strategy predominated, and in the Kekhta River—the mykiss with migratory strategy. The key parameter controlling the prevalence of life strategies in each river is the ratio of the area of spawning grounds to the area of feeding grounds and their productivity. The hypothesis is confirmed that, in complex river systems, due to the diversity of biotopes and a higher productivity, the food resources are sufficient for maturation of mykiss and for realization of the resident life strategy (without migration to the sea for feeding). In small rivers of the channel type with their insufficient food resources, the specimens having a migratory life strategy prevail.

Experimental Determination of the Life History Strategy of the Kamchatka Mykizha Parassalmo mykiss (Walb.) (Salmonidae, Salmoniformes) on the Basis of Analysis of the Sr/Ca Ratio in Otoliths

The life history strategy of mykizha salmon species in the Kamchatka Peninsula is characterized by significant diversity [1, 2]. Although the mykizha phenotypes with different types of life history strategy most frequently occur symmetrically in the rivers of the western coast of the Kamchatka Peninsula, their ratio in individual rivers is not maintained at a constant level but may vary from year to year depending on environmental conditions [2, 3]. It was suggested that, during the life of one specimen, its life history strategy may change from migratory to resident and vice versa [2, 4]. Similar transformations have been described in various species of salmonids [5, 6], and they are thought to be of epigenetic origin [1, 2]. The problem of interaction between the anadromous and resident forms of mykizha in the rivers of the Kamchatka Peninsula is the key problem of the structure of the species. To date, the life history strategy of mykizha has been studied mainly based on the analysis of scale structure [1, 2]. However, the possibility of subjective estimates is a serious disadvantage of this method. Therefore, it is particularly important to use accurate instrumental methods ensuring more reliable determination of the specific features of life history strategy of each fish specimen during its life cycle.

Population structure of arctic lamprey Lethenteron camtschaticum from the Kol River (Western Kamchatka)

Phenetic diversity is investigated and the taxonomic status of lampreys (Petromyzontidae) from the Kol basin (Western Kamchatka) is verified. Typically anadromous lamprey, anadromous lamprey forma praecox, resident lamprey, smolts, and larvae of lamprey are discovered and described. Their comparative analysis is made by standard morphometric characters. Differences between the forms by plastic characters depend on size and weight. No significant differences are found by major taxonomic characters between the forms of anadromous and resident lampreys which would indicate their taxonomic separation. Phenetic types of spawners are representatives of the population of one complexly structured species represented by life forms realizing different life history strategies (anadromous and resident), and belong to the species Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811).

On Joint Spawning of Anadromous and Resident Mykiss Parasalmo mykiss in Rivers of Western Kamchatka

The fact of joint spawning of anadromous and resident mykiss Parasalmo mykiss is reliably recorded in the basin of the Kol River (Western Kamchatka). The obtained data on relationships of these forms during spawning indicate to their conspecificity. This species should be protected as a whole, in all diversity of its forms.

Seasonal Races of Chum Salmon Oncorhynchus keta and Their Interrelations in Kamchatka Rivers

Dates of migration and spawning, size-age structure, and fecundity of seasonal races of chum salmon Oncorhynchus keta from the Kol River are reviewed, those of early summer, late summer, and autumn races, as well as localization and structure of their spawning grounds, bed-sediment particle size in the redds, hydrological and thermal conditions on spawning grounds, and meristic characters of races. Special traits of reproduction of seasonal races within the species range and in Kamchatka in particular are discussed. The number of seasonal races in rivers depends on the presence of various habitats suitable for spawning. In rivers with complicated hydrogeomorphological structure, the number of seasonal races increases. Variations of types of seasonal races in a particular river and in the whole species area are epigenetic, i.e., they depend on the hereditary genetic program and presence of conditions providing its realization via various channels.

Sexual Dimorphism and Some Special Traits of Spawning Behavior of the Arctic Lamprey Lethenteron camtschaticum

The sexual dimorphism and the role of secondary sexual characters in the spawning period of the Arctic Lamprey Lethenteron camtschaticum from the Utkholok basin (Kamchatka) are studied for the first time. The importance of the urogenital papilla in males and of the keel in females during egg fertilization and in construction of the redd is shown. By visual observations, underwater and above water videography, two forms of spawning behavior are revealed: group behavior in the current and paired behavior in the inshore part of the river, where the current is slower. The typically anadromous form, the anadromous forma praecox, and river lamprey reproduce together. The strategy of the spawning behavior is directed first of all towards better fertilization of eggs and finally towards reproductive success of the species.

Ecological analogies in the Pacific lamprey Lethenteron camtschaticum and the mykiss Parasalmo mykiss in Kamchatka

Ecological analogies between the Pacific lamprey Lethenteron camtschaticum and various species of salmonids (Salmonidae) are noted. Close analogies are found with the mykiss Parasalmo mykiss. The lamprey and mykiss are characterized by spawning in spring. In their populations there are specimens with anadromous and riverine life strategies. The mechanism of formation of life strategies seems to be similar in both species. The major role belongs to the trophic factor determining the level of energy resources necessary for maturation. Such analogies result from epigenetic changes in principal ecological parameters and are formed under the influence of similar environmental factors.

Population structure of the masu salmon Oncorhynchus masou from the Kol River (Western Kamchatka) and geographic variation in the species area

According to materials from original investigations in Kamchatka as well as published data, the population structure and geographical variation of the masu salmon Oncorhynchus masou are considered in the species area. The intraspecies structure, dates of their run to rivers, dates of spawning, traits of spawning, size-age and sex composition, fecundity, biological traits of parr, downstream migration of smolts are investigated. The relationship is shown between the manifestations of geographical variation of masu salmon and the factor of temperature. It is assumed that the global warming of climate would contribute to the advancement of this species to northern areas and to the increase in its abundance.