1063-0740/03/2903- $25.00 © 2003
Russian Journal of Marine Biology, Vol. 29, No. 3, 2003, pp. 194–198.
Original Russian Text Copyright © 2003 by Biologiya Morya, Menshutkin.
The application of individual-based modeling in
research on ﬁsh number dynamics reveals new oppor-
tunities for studying the reorganization of the genetic
structure of a population under varying natural and
anthropogenic conditions. The problem of similar reor-
ganizations in populations of Paciﬁc salmons arose a
long time ago [1, 3]; however, the previous studies had
primarily a descriptive character. The method of indi-
vidual or object-based programming enables another
approach to this problem, i.e., computer modeling.
The population of
spawns in Dal’neye Lake was chosen as the subject for
the model. It is one of the most well studied populations
of Far East salmon over a number of years , includ-
ing one of the ﬁrst applications of computer modeling
in ichthyology . The 1969 model was based on the
balance of bioenergetic ratios and assumed full unifor-
mity of all the individuals in the population, except for
the age and body weight. That model was deterministic.
In the present work quite another approach is used:
each individual of the population had its own parame-
ters, distinct from those of other individuals, and its
own fate. The generalization of the life histories of all
individuals results a pattern of population dynamics.
Such a model, naturally, should be stochastic, which
more adequately displays the properties of wildlife than
the deterministic approach.
Description of the model
Analysis of the population structure of
from Dal’neye Lake (Fig. 1) showed that the
maximum individual life span in the lake was four
years, but usually youth of this species headed to the
sea at the age of one, two, or three years. The formation
of dwarves (individuals that attained sexual maturity in
fresh water) may begin from two years of age. The sea
part of the sockeye population differs in the number of
years spent by ﬁshes in the lake.
An element of the model is that an individual of
is imparted the following traits: sex; age;
number of years spent in fresh water; location of indi-
vidual in the sea or in the lake at the present time; indi-
vidual body weight; a degree of sexual maturity; and
genotype. It was assumed that the time interval of the
model for the fresh-water period of life of sockeye
Modeling of the
Population of Dal’neye
Lake (Kamchatka) Applying an Individual-Based Method
V. V. Menshutkin
The International Ecological Centre of the Polish Academy of Sciences, Dziekanow Lesny, Poland
Received December 26, 2002
—A computer model of the sockeye salmon
population from Dal’neye Lake
(Kamchatka) based on the results of long-term research was developed. As opposed to an earlier published
model , the stochastic approach and individual-based method were used in the present model. The applica-
tion of such techniques in the model has enabled study of the dynamics of the genetic structure of the population
under the effect of varying environments, both in the sea and in the fresh-water period of the sockeye’s life, and
discovery of patterns of transition from the cyclic ﬂuctuation mode to the mode of chaotic change of number.
model, individual-based method, genetic structure of population.
Diagram of the
spawning in Dal’neye Lake.
—spawning schoal; K2 and
—the sea period of life; 0+…4+—age
groups of juveniles; 2
+—age groups in the sea
(index—number of years spent in fresh water).