The potential biological effects of the planned seismic survey have been discussed in considerable detail in an Environmental Assessment that has been made available to Canadian and U.S. regulators and to the public.  That assessment included an extensive evaluation of the issues and described numerous planned mitigation and mitigation measures appropriate to reduce and characterize impacts, and to meet the requirements of Canadian and U.S. authorities. The seismic acquisition will occur over ~10-15 days far offshore, exclusively in deep waters, where sound dissipates more rapidly with increasing distance.  Possible marine mammal encounters will be restricted to deep-water species, typically widely dispersed.  During the summer many species tend to feed further inshore.  The expedition was carefully scheduled to reduce encounters with marine mammals. This cruise is subject to the marine scientific research consent regime as described in Part XIII of the United Nations Convention on the Law of the Sea. Accordingly, since the research is to occur in the NE Pacific inside the Canadian Exclusive Economic Zone (EEZ), the United States sought and has received a Letter of Agreement from Canada’s Department of Fisheries and Oceans (DFO) for this research.  The Langseth is always operated in accordance with rules and regulations set forth in the US Marine Mammal Protection Act, Endangered Species Act, and National Environmental Policy Act and receives permits reviewed and approved by fisheries biologists and endangered species experts with the U.S. National Marine Fisheries Service, part of the National Oceanic Atmospheric Administration.  Additionally, in the presently planned project in the Endeavour Marine Protected Area more precautionary procedures will be followed in accordance with requirements set forth by Canada’s DFO.  The airguns will be shut down immediately if marine mammals are observed to approach extended mitigation zones (in excess of 1200 m from the ship’s sound source) established to minimize adverse effects of the sound. Also, besides the systematic visual observations to be conducted by the observation team, a towed array of hydrophones will be used, on a 24-hr per day basis, to detect marine mammals that call in the vicinity of the seismic vessel.  That is standard practice when the Langseth is operating an airgun array of the type planned for use here. Lastly, some concern was raised about possible effects of the hydrophones placed on the seafloor to receive the signal from the seismic source.  There will be a maximum of 5 seismometers deployed within the MPA and they will be carefully placed to avoid any damage to active vent communities.

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