The TINRO-Center has been conducting large-scale and systematic surveys on the pollock stock and biomass analysis as well as the assessment of pollock stock distribution and its role in the ecosystem of the Sea of Okhotsk since 1983.
Pollock stock surveys conducted by the TINRO-Center in the Sea of Okhotsk can be considered as the largest fish stock surveys in the world fishery scientific research practice.
Currently the stock assessment in the Bering Sea is fulfilled in the summer and autumn season by means of bottom and acoustic surveys in the areas of Russia and the USA as of within the scope of the joint researches with American scientists. Up to 1992 the pollock stock assessment in the Bering Sea had been conducted by means of ichtioplankton method either.
All kinds of surveys arranged by TINRO-Center are comprehensive ones and provide the simultaneous conduction of both different types of works and various information collecting.
Ichtioplankton survey includes the seining of pollock floating spawn with plankton net and the assessment of the spawn numerousity in the basic spawning grounds,
Trawling surveys cover trawling works, pollock and other fish species, squid and jellyfish measurement within the whole water area of the survey,
Bottom surveys provide the shelf trawling with the full analysis of the fish and sea-floor animals catch,
Trawl-acoustic surveys make registration and accumulation of the acoustic measurements with conducting of the control deep-sea and over-trawling.
The collection of data on plankton cenosis and pollock food as well as that of the environment is conducted simultaneously, providing the full illustration of the ecological system conditions in the Sea of Okhotsk and the Bering Sea.
The TINRO-center specialists on the surveys in the Sea of Okhotsk - the seining of pollock floating spawn with plankton net
There are approximately 10 - 15 annual surveys conducted by the Russian Far East fishery scientific institutes enabling to cover all Pollock stocks in the Russian zone for accurate stock assessment. The surveys are conducted by means of both the research vessels owned by the fishery institutes and by the chattered ones.
Weighing out the trail net on the TINRO research vessel “Professor Kaganovsky” while trawling survey
The annual expeditions arranged by the TINRO-Center on the pollock stock assessment in the Sea of Okhotsk are as follows.
The spring complex survey in the Sea of Okhotsk, which begins at the Southern Kuril Islands in the second part of March, the researches along the Western Kamchatka and in the Shelikhov Strait in the beginning of April, the one in the Northern part of the Sea of Okhotsk in the beginning of May and the ending of the expedition at the Eastern part of the Sakhalin Island in the first days of June.
Picture –The scheme of complex survey in the Northern part of the Sea of Okhotsk (April-May 2011)
The complex surveys for pollock assessment are carried out annually in the summer and autumn term in the Sea of Okhotsk, the direct surveys are performed in the winter and spring seasons.
In the summer and autumn term the complex trawl-acoustic survey is carried out in the Northern part of the Sea of Okhotsk only (without the Southern Kuril Islands region).
In the summer and autumn season the bottomed trawling survey and – if possible – the trawl-acoustic survey are conducted in the Western part of the Bering Sea.
Picture – The scheme of the trawl-acoustic (the USA water area) and the bottomed (Russian waters) surveys on the pollock stock assessment in the Bering Sea.
The TINRO-Center specialists take part in the regular joint trawl-acoustic surveys in the water areas of the USA and Russia.
In addition to these major researches TINRO and other institutes have scientific observers program and work on the commercial vessels either. There are on average 10-15 scientific observers from all fishery institutes of the Russian Far East working in the fishery in the fishing season of the Sea of Okhotsk. Their main task is to monitor and collect the fishery statistics, to define and analyze the length frequency of the catch, spawn departing and other fishery and biological data. These materials are further deployed in various types of forecasts (quarter, seasonal, annual) as well as in the managerial decision making on the pollock fishery adjustment.
In summary, all these kinds of research allow Russian scientists to obtain instructive data on the pollock stock assessment in the Sea of Okhotsk and the Bering Sea.