Salvelinus boganidae lake Sobachie (Putorana plateau): age, growth, demographic parameters

Abstract

Lake-river char, described as Boganid char, in the lake Sobatchie (Putorana Plateau) is one of the main representatives of the ichthyofauna. There were not any special works examined the char ecological and demographic parameters peculiarities inhabiting this water body. Present day studies are based on small sample sizes. The purpose of this publication is to determine the age, size, and demographic characteristics of the Boganid char in Lake Sobatchie. The paper presents the results of studies of the size-age and demographic parameters of the Boganid char of Lake Sobatchie for 2013-2018 The studies were carried out according to the methods existing in modern ichthyology. The catches included fish aged from 2 to 13 years, females aged 7-10 and males aged 8-11 dominated. The length of the char (SL) ranged from 157 to 620 mm, the mass is from 40 to 4000 g. There was a great variability in growth: the sizes of fish of the same age can differ by 1.5-3.2 times, the weight - by 5-45 times. The sex ratio is 60:40 in favor of females. Sexual maturity occurs at the age of 5 years when females reach length (SL) 307 mm, weight - 348 g; males - 286 mm and 275 g, respectively. The period of puberty is extended to 7 years. The presence of a small part of immature fish in older age groups may indicate that some producers miss their annual spawning. The values of individual fecundity of the Boganid char range from 540-8207 eggs, relative - 0.963.53 eggs. Fertility values functionally depend on the age and size of fish with high coefficients of determination. The fish migration in the lake Sobatchie and its food items information is provided. The conclusion is made that the number of Boganid char in the lake Sobatchie is limited by the capacity of the spawning grounds of the river Horonen. The Boganid char size and age composition research results are presented. Fish aged from 2 to 13 years old were found in the catches, females aged 7-10 and males aged 8-11 years were dominating. Boganid char length reach from 157 up to 620 mm, weight – 40-4000 g. The large variability of growth was noted: the same-aged fish sizes can be varied by 1.5-3.2 times, weight – 5-45 times. The sex ratio is 60:40 in favor of females. Puberty occurs at the age of 5 years when females reach the 307 mm length and 348 g weight; males - 286 mm and 275 g, respectively. The puberty period is stretched up to 7 years. The Boganid char individual fertility value fluctuates from 540 up to 8207 caviar. The fertility values functionally depend on the fish age and size with high determination coefficients. It was concluded that Lake Sobatchie Boganid char population limited by the river Horonen spawning areas capacity.