ISSN 1063-0740, Russian Journal of Marine Biology, 2017, Vol. 43, No. 1, pp. 57–64. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © O.Yu. Busarova, G.N. Markevich, R. Knudsen, E.V. Esin, 2017, published in Biologiya Morya.
Trophic Differentiation of the Nosed Charr Salvelinus schmidti
Viktorovsky, 1978 in Lake Kronotskoe (Kamchatka)
O. Yu. Busarova
*, G. N. Markevich
, R. Knudsen
, and E. V. Esin
Far Eastern State Technical Fisheries University, Vladivostok, 690087 Russia
Kronotsky State Nature Biosphere Reserve, Elizovo, 684000 Russia
University of Tromsø, Tromsø, N-9022 Norway
Russian Federal Research Institute of Fisheries and Oceanography, Moscow, 107140 Russia
Received May 19, 2016
Abstract⎯The nosed charr Salvelinus schmidti that inhabits the littoral zone of Lake Kronotskoe is divided
into two groups according to food preferences and parasite fauna. Fish of the first group (G) predominantly
feed on gammarids and are characterized by a high infestation with Cystidicola farionis, Cyathocephalus trun-
catus, and Crepidostomum spр. Fish of the second group (A) do not consume gammarids but feed mostly on
chironomid larvae and pupae and on mollusks; the predominant parasites are Phyllodistomum umblae and
Proteocephalus longicollis. The significant difference in the abundance of C. farionis, which remains in fish at
least for 2 years, is indicative of a long-term and persistent trophic diversification between the charr groups.
Moreover, significantly higher growth rates, a larger body size, and a longer lifespan are observed for fish of
group G. The feeding strategy of the nosed charr is maintained throughout the life and does not depend on
the sex of fish and their distribution within the littoral zone of the lake.
Keywords: feeding, indicator parasites, littoral, ecological groups of fish, trophic specialization
Lake charrs of the genus Salvelinus Richardson,
1836 are characterized by division into sympatric
groups with discrete phenotypes. The diversification is
generally associated with adaptations to the utilization
of different food resources and manifests itself in the
appearance of benthos-feeders and consumers of
other resources (predators, plankton-feeders) [35, 43,
52]. There are also reports of separation of benthivo-
rous charrs into several forms in a number of lakes.
Most often, this is connected with different depths of
habitat [50, 53]; however, some cases are known where
pairs of littoral benthivorous groups co-occurred.
Thus, in Lake Thingvallavatn in Iceland, two morphs
of benthivorous charrs with a similar diet occupy an
epibenthic biotope and space between the lava blocks
[41, 54]. In Norway, bottom-dwelling charrs in Lake
Fjellfrosvatn segregate into two groups that differ in
some morphological features and specialize in feeding
on gammarids or on other benthic organisms .
Specialized benthivorous charrs dwell in the
coastal zone of Lake Kronotskoe [12, 15, 28, 34].
Some authors consider them as a distinct species, the
nosed charr Salvelinus schmidti Viktorovsky, 1978 [15,
34]; while others consider them as a specialized form
of the Dolly Varden charr S. malma (Walbaum, 1792)
[4, 32]. A morphological peculiarity of the nosed charr
is the noticeably lower position of its mouth and the
distinctive overhanging of the upper jaw, suggesting
feeding specialization of this species . There is evi-
dence of the differentiation of nosed charr population
in terms of feeding [14, 28] and habitats [15, 34].
One of the methods for distinguishing the ecologi-
cal divergence of charrs is a combination of analyses of
their food composition and parasite fauna [41, 44, 47].
The analysis of parasite infestation allows evaluation
of the feeding habits of fish for a period from several
months to several years [7, 10–12, 18, 40, 46]. The
present study focuses on the feeding preferences and
parasite fauna of the nosed charr from Lake Kro-
notskoe and on verifying the hypothesis that different
steady trophic groups exist within the charr popula-
MATERIALS AND METHODS
Lake Kronotskoe is the largest freshwater body in
Kamchatka Peninsula; it is located at 370 m above sea
level and 40 km away from the eastern coast. The area
of the lake is 246 km
, the average depth is 58 m, and
the maximum depth is 136 m [1, 3]. There are approx-
imately 20 permanent tributaries, among them six riv-