Integrated study of benthic foraging resources for Atlantic walrus (Odobenus rosmarus rosmarus) in the Pechora Sea, south-eastern Barents Sea

The Atlantic walrus,Odobenus rosmarus rosmarus, forms a herd of nearly 4,000 heads in the Pechora Sea (south-eastern Barents Sea). The Near Threatened status ofO. rosmarus rosmarusand the relative isolation of the Pechora Sea population, as well as the potential impacts of human activities in the area, make it important to characterize key habitats, including feeding grounds, in order to protect the species. The aim of the present study was to integrate multiple sources of environmental and biological data collected by satellite telemetry, remotely operated vehicle (ROV), and benthic grab sampling to examine the distribution and diversity of benthic foraging resources used by walrus in the Pechora Sea. Analysis of satellite telemetry data from seven males tagged on Vaigach Island helped to identify areas of high use by walruses near haulout sites on Matveev and Vaigach islands, and in between. Field data were collected from those feeding grounds in July 2016 using ROV video recordings and bottom grab sampling. Analysis of 19 grab stations revealed a heterogeneous macrobenthic community of 133 taxa with a mean biomass of 147.11 +/- 7.35 g/m(2). Bivalve molluscs, particularlyAstarte borealis,Astarte montagui, andCiliatocardium ciliatum, dominated the overall macrobenthic biomass, making up two-thirds of the total. Analysis of 16 ROV video transects showed high occurrences of mobile benthic decapods (3.03 +/- 2.74 ind./min) and provided the first direct evidence that areas actively used by walrus in the Pechora Sea overlap with the distribution of the non-native omnivorous snow crab,Chionoecetes opilio. Integrating multiple data sources provides an early foundation for the kinds of ecosystem-based approaches needed to improve Pechora Sea resource management and to underpin Russia's nascent marine spatial planning initiatives. Factors that need to be considered in marine spatial planning include impacts on benthic feeding grounds from offshore oil and gas development and the spread of the snow crab.