The impact of variations in oceanographic conditions on distribution, aggregation structure and fishery pattern of redfish (Sebastes mentella Travin) in the pelagial of the Irminger Sea and adjacent waters

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Analysis of data from acoustic trawl surveys of Sebastes mentella in the Irminger Sea pelagial suggests that extension of redfish distribution to the southwest observed since the mid-1990s was caused by migration of some aggregations from the traditional feeding areas due to an increased advection of Atlantic waters by the Irminger current and higher temperatures of the surface layer (TSL). However, the use solely of the data from surveys conducted every other year limits the possibility to study the impact of variations in oceanographic conditions on distribution, aggregation structure and fishery pattern of redfish in the long term, although such information is essential for the development of sustainable harvesting strategies for fish resources. Data on monthly mean TSL fields at the regular grid nodes for 1982-2008 were used as additional oceanographic indices. To identify and forecast TSL data, the aliquant frequency method was used. Besides, the calculations used air temperature data for 1949-2008 to derive the trend component which was applied to fill in the gaps in the basic TSL data and make a projection. Interannual spatial bathymetric variability in some population parameters of redfish in the Irminger and Labrador Sea was analysed. СPUE for the northeastern and southwestern fishing area was calculated. A statistically significant correlation between CPUE and TSL was revealed, which suggests that CPUE indices directly depend on primary production conditions during spring. CPUE forecasted for 2009-2010 shows a decreasing trend in the Labrador Sea. A strong impact of oceanographic conditions on different fishery patterns for redfish was demonstrated. It was concluded that the proposed division into the northeastern and southwestern fishing areas, as well as the use of two units in the management of the redfish stock in the pelagial of the Irminger Sea and adjacent waters are not efficient and lack scientific substantiation.