New forms of char fish have been discovered in the Kronotsky Lake basin

New forms of char fish have been discovered in the Kronotsky Lake basin.

05.01.2023

The staff of the Kronotsky Reserve continues to study the mechanisms of fish speciation in freshwater reservoirs of Kamchatka. The scientists have recently summed up the results of the last field research season.

Kronotsky Lake is one of the most interesting objects for studying the formation of new fish species. During an extensive multi-year research program, the staff of the Kronotsky Nature Reserve and research institutions of the Russian Academy of Sciences described the unique char fish population in the lake. There are 8 isolated forms which differ in the nature of nutrition and body structure: long-headed, big-mouthed, small-mouthed, white and four varieties of snouted char. This is the largest number of salmon fish found in one reservoir in the world, and their study might be key to understanding the fundamental laws that determine the course of animal evolution processes in general.

Recently the researchers have faced the question: could there be additional forms of char fish inhabiting only certain specific areas in the diverse conditions of Kronotsky Lake? Over the past two years, scientists have carefully studied three types of ecosystems: the well-heated bays, relict partially or completely isolated reservoirs in the basins of the main tributaries, and the culverts of the main rapids in the upper reaches of the Kronotskaya River flowing out of the lake.

"We found out that the peripheral parts of one of the most heated bays of the lake – Krasheninnikov – are inhabited by fish with specific characteristics. They resemble typical predatory char, but in terms of nutrition they are in an intermediate niche between predators and benthophages (feeding on bottom organisms). A large population of residential fish, which do not have specialized morphological features and feeding habits, was found in the sluicing boilers of the rapids. Genetic analysis has shown that these chars are separate forms belonging to the line of predatory chars in the lake," said Grigory Markevich, senior researcher at the Kronotsky State Reserve.

New data have significantly expanded the understanding of the diversity structure of the Kronotsky Lake basin ecosystem. Extensive biochemical materials have been collected for all ten forms of char, which make it possible in the near future to determine the physiology features for each of the unique fish groups.

Also in 2022, studies of char populations of local ecosystems of the Kamchatka River basin, the oldest and largest river basin in the Kamchatka Territory, have been continued. Various salmon fish have been preserved here and continued to evolve during periodic glaciations. In the course of previous studies, two endemic groups of predatory char have been described in this area.

The researchers suggest that the reasons for why there are so many isolated fish forms lie solely in the general features of the temperature regime of our lake ecosystems, which provides atypical conditions for the passage of malma for incubation of eggs, as well as nutrition. The collected materials are now being processed and will soon be analyzed.