1063-0740/04/3001- © 2004
Russian Journal of Marine Biology, Vol. 30, No. 1, 2004, pp. 65–69.
Original Russian Text Copyright © 2004 by Biologiya Morya, Il’inskii, Merzlyakov, A. Vinnikov, K. Vinnikov, Buryak.
The West Kamchatka shelf is Russia’s richest ﬁsh-
ing area in the absolute and relative abundance of ﬁsh
and invertebrate stock . Exploitation of its resources
has continued already for more than a hundred years.
Signiﬁcant ﬂuctuations in the number of many com-
mercial objects have been recorded in that period,
which were caused also by excessive ﬁshery pressure.
Since 1996, the KamchatNIRO and TINRO-center
have jointly carried out annual bottom surveys on the
shelf of West Kamchatka. Analysis of the information
collected enables us to speak about essential changes in
the bottom ﬁsh community that have occurred recently
in that area . Apparently, changes in pelagic commu-
nities [7, 9] caused by changes in the climate–oceano-
logical periods have been mirrored also in the bottom
ﬁsh communities. Beyond the West Kamchatka shelf,
similar changes were revealed in the bottom biocenoses
of the northern part of the Sea of Okhotsk  and on the
shelf of the western part of the Bering Sea .
MATERIAL AND METHODS
The initial data for calculations were collected dur-
ing bottom trawl surveys on the shelf of West Kam-
chatka in the 2002 summer season. The allocation of
trawl sections corresponded to the standard pattern
used from the end of the 1950s. During the survey, 156
trawlings from onboard RV “Professor Kaganovsky”
and 163 trawlings from onboard RV “Sopochnoye”
were carried out. Depths from 15 up to 200 m were sur-
veyed. The trawling sections were performed in a sim-
ilar pattern for both vessels; additionally, the same type
of bottom trawl, DT 27.1, was used, and the trawlings
were carried out at the same speed, 3 knots, and for the
same duration, 30 min.
The same technique was used for calculation of the
absolute values of the biomass of various ﬁsh species,
as in similar calculations for a comparison of the results
of bottom surveys on the West Kamchatka shelf for a
ﬁve-year period . This was considered in detail in the
papers of Volvenko [3, 4] and amounts to an estimation
of the relative density (kg/km
) of species at each trawl-
ing station by the following formula:
is the biomass of ﬁshes, kg;
is the actual
weight of ﬁshes in a catch, kg;
is the speed of the
is the duration of trawling;
is the hori-
zontal opening of the trawl mouth, km;
is the catch
factor; 1.852 is the number of kilometers per nautical
The horizontal opening of the trawl mouth was con-
sidered constant (irrespective of depth, trawl speed,
lengths of warps, etc.) for each trawl system. Based on
estimation it was assumed to be about 60% of the
length of the upper ﬂoat without buoy ropes. Standard
catch factors formerly used for those ﬁsh species and
bottom trawls were applied (see, e.g., ).
The absolute biomass values were estimated indi-
vidually for the depth ranges and for two statistical
areas, based on the average density of ﬁshes (kg/km
and on the areas of the bathymetric sites.
Current Trends in the Condition of Bottom Fish Communities
from the West Kamchatka Shelf
E. N. Il’inskii
, A. Yu. Merzlyakov
, A. V. Vinnikov
K. A. Vinnikov
, and P. N. Buryak
Paciﬁc Fisheries Research Center (TINRO-Center), Vladivostok, 690600 Russia
Kamchatka Research Institute of Fisheries and Oceanography, Petropavlovsk-Kamchatksky, 683602 Russia
Received June 6, 2003
—Based on the data of two summer surveys carried out in 2002, the biomass of bottom ﬁshes of the
West Kamchata Shelf was assessed. The obtained results were considered within the series of similar annual
assessments conducted since 1996. It was displayed that against the background of some increase in the total
biomass of bottom ﬁshes, the biomass of the plaices prevailing there, which had previously been the two dom-
inating species had decreased. As a result of the quantitative variations that occurred, the present community
structure differs considerably from that observed over the past twenty years.
: bottom ﬁshes, ichthyocen, shelf, biomass, West Kamchatka.