Influence of environmental factors on fish stocks in the Baltic Sea

Abstract

The aim of this article: assess the impact of abiotic conditions on aquatic biological resources (sprat, herring, cod) of the Baltic Sea. The need for this study is due to the pronounced climate variability in the modern period. There is an increased role of the impact of environmental conditions on commercial fish species and, often, unfavorable for their spawning, survival of offspring, feeding, etc. Methods used: carried out an integrated ecosystem analysis using the method of principal components in the R software environment. To detect statistically significant levels of changes in the time series of principal components, the STARS program, represented by an Excel add-in, was used. For the analysis of abiotic conditions, long-term series of air temperature, data from regular oceanological observations at a monitoring station were used. Since the stocks of commercial fish species in the Baltic Sea are transboundary, the values of their spawning biomass and biological parameters of populations were analyzed according to the data ofthe ICES Working Groups. Novelty: this is the first time that such an analysis for a 30-year period adapted to the Russian water area in SD ICES 26 has been carried out. Result: an integrated analysis of the abiotic and biotic components of the sea over the past three decades showed «mesoscale» shifts in 2002 and 2013. The direct and indirect impact of climate on the fish stocks of the Baltic Sea was an important unfavorable factor determining the current state, size and weight parameters, reproductive capacity and stocks dynamics. The most pronounced negative impact of environmental factors was noted for the stock of cod. Practical significance: the results of the analysis carried out are necessary when predicting the catch of aquatic biological resources in the Baltic Sea for the short and long term, for making management decisions on the regulation of fishing in terms of understanding the risks in the current conditions of climate change.