The research included a complex of ichthyological, hydrological, hydrochemical, hydrobiological and meteorological observations during the spawning and incubation of White Sea herring eggs. Specialists from the Northern Branch of VNIRO noted very powerful approaches of herring to spawn, significantly higher than last year. The warming of water masses occurred much faster than the long-term average values, smoothly, without sudden temperature changes, the number of days with wind strength above 6 m/s was extremely low, and there was not a single storm during the work. However, under these environmental conditions, the number of larvae during harvests was unusually low.
During the study period, herring was caught constantly and dominated all catches, regardless of the strength and direction of the wind, which usually makes noticeable adjustments to the composition of catches. On average, during the work the bycatch amounted to only 4% of the total catch, this is the lowest figure over the last 15 years of research. The average length of the herring was 13.5 cm with an average weight of 17.4 g. Bycatch included polar flounder, Asian smelt, navaga, river flounder, northern ruffed flounder, lumpfish, European sculpin, European eelpout, and roach.
Also, during the research, samples of macrozoobenthos, ichthyo- and zooplankton, data on water temperature and salinity were collected, water samples were taken to determine the quantitative characteristics of phytoplankton, determine the content of nutrients, as well as to assess the pollution of the habitat of aquatic biological resources with aluminum and phenols, measurements were taken pH and oxygen content dissolved in water. Throughout the entire period of work, meteorological observations were carried out.
All collected data will be used to prepare forecast materials and develop measures to regulate fishing in this area, as well as to assess the living conditions of aquatic biological resources in the Onega Bay of the White Sea.
VNIRO press service