Evaluating the Impact of Oceanographic Field Variability on Atlantic Mackerel Distribution Within Russian Fishing Grounds in the Northern Norwegian Sea

Abstract

Based on fishing records from 2015, 2016, and 2020, this study analyzes the dependence of Atlantic mackerel catch distribution by the Russian fleet on oceanographic conditions in the northern part of the Norwegian Sea (north of 68.5° N). Four types of parameters characterizing fronts and frontal zones are considered: the Lagrangian indicator S, describing water dynamics, along with temperature, salinity, and density in the upper ocean layers, which are traditionally used to identify thermohaline fronts. Gradients of these characteristics are calculated based on these parameters, and the distance from fishing locations to the nearest fronts is evaluated. A unified methodology is applied to automatically define frontal zones using a probability distribution function. To eliminate the dependence of statistical analysis results on limited sampling, a comparison with a random sample was conducted. Histogram analysis of actual catches shows that fishing zones are often located 10–15 km from fronts. It was found that the density of the upper ocean layers has the greatest influence on the distribution of Atlantic mackerel fishing aggregations, while temperature fronts also significantly impact the formation of fishing aggregations.