Aarhus University Seal / Aarhus Universitets segl

No. 238: Marine mammals in Finnish, Russian and Estonian waters in relation to the Nord Stream 2 project. Expert Assessment

Sveegaard, S., Galatius, A. & Tougaard, J. 2017. Marine mammals in Finnish, Russian and Estonian waters in relation to the Nord Stream 2 project. Expert Assessment. Aarhus University, DCE – Danish Centre for Environment and Energy, 80 pp. Scientific Report from DCE – Danish Centre for Environment and Energy No. 238. http://dce2.au.dk/pub/SR238.pdf


Nord Stream 2 AG (NSP2) is planning the construction of a second gas pipeline in the Baltic running from Russia to Germany. In this report, the potential impacts on marine mammals in relation to the Finnish and Russian sections of this gas pipeline are assessed. The construction and operation may have impacts on marine mammals in Finnish, Estonian and Russian waters and in these waters, the most relevant marine mammal species are grey seal and ringed seal. Also harbour porpoises are occasionally present. The Gulf of Finland ringed seals are of particular concern, as the planned pipeline route intersects their range and since this subpopulation is currently threatened with extinction (by other factors). The assessment is based on information and studies conducted during the Environmental Impact Assessments for marine mammals from Nord Stream, the NSP2 baseline report for marine mammals, models on sedimentation and underwater noise in Russian and Finnish waters as well as relevant literature. No new fieldwork was conducted. In the report, the pressures related to the periods of construction, precommissioning, commissioning and operation of the gas pipeline are described and assessed in relation to the sensitivity of marine mammals. The main potential impacts are underwater noise, sediment spill and changes to the habitat. All impacts, except munition clearance (potentially causing blast injury and permanent hearing damage), are assessed to have a negligible to minor significance. The impact of munition clearance may be reduced by the use of deterrence devices (seal scarers) in a way comparable to what was done during construction of the Nord Stream Pipeline. This mitigation will reduce the impact of munition clearance from moderate to minor for harbour porpoises and from major to moderate for both seal species.