Environmental Assessment of a Marine Geophysical Survey by the R/V Marcus G. Langseth in the central Gulf of Alaska, June 2011 Prepared for United States Geological Survey Pacific Coastal and Marine Science Center 345 Middlefield Rd. Menlo Park, CA 94025 and National Science Foundation Division of Ocean Sciences 4201 Wilson Blvd., Suite 725 Arlington, VA 22230 by LGL Ltd., environmental research associates 22 Fisher St., POB 280 King City, Ont. L7B 1A6 14 January 2011 Revised 15 April 2011 LGL Report P1198-1 Environmental Assessment for a USGS GOA Seismic Survey, 2011 Page ii Table of Contents TABLE OF CONTENTS Page ABSTRACT .................................................................................................................................................... vi LIST OF ACRONYMS ................................................................................................................................... viii I. PURPOSE AND NEED .................................................................................................................................. 1 II. ALTERNATIVES INCLUDING PROPOSED ACTION ..................................................................................... 2 Proposed Action ................................................................................................................................. 2 (1) Project Objectives and Context .......................................................................................... 2 (2) Proposed Activities ............................................................................................................. 2 (3) Monitoring and Mitigation Measures ................................................................................. 6 Alternative Action: Another Time .................................................................................................... 13 No Action Alternative ...................................................................................................................... 13 III. AFFECTED ENVIRONMENT .................................................................................................................... 14 Oceanography ................................................................................................................................... 14 Marine Mammals .............................................................................................................................. 15 (1) Mysticetes ......................................................................................................................... 15 (2) Odontocetes ...................................................................................................................... 24 (3) Pinnipeds .......................................................................................................................... 30 (4) Marine Fissiped ................................................................................................................ 33 Sea Turtles ........................................................................................................................................ 34 (1) Leatherback turtle ............................................................................................................. 34 (2) Green turtle ....................................................................................................................... 35 Seabirds ............................................................................................................................................ 36 (1) Kittlitz’s Murrelet ............................................................................................................. 36 (2) Marbled Murrelet ............................................................................................................. 37 (3) Yellow-billed Loon .......................................................................................................... 37 (4) Steller’s Eider ................................................................................................................... 38 (5) Short-tailed Albatross ....................................................................................................... 38 Fish Resources .................................................................................................................................. 39 Essential Fish Habitat and Habitat Areas of Particular Concern ...................................................... 41 Commercial Fisheries ....................................................................................................................... 41 IV. ENVIRONMENTAL CONSEQUENCES...................................................................................................... 44 Proposed Action ............................................................................................................................... 44 (1) Direct Effects and Their Significance on Marine Mammals and Sea Turtles .................. 44 (2) Mitigation Measures for Marine Mammals and Sea Turtles ............................................ 59 (3) Numbers of Marine Mammals that Could be “Taken by Harassment” ............................ 60 (4) Conclusions for Marine Mammals and Sea Turtles ......................................................... 65 (5) Direct Effects on Fish, Fisheries, and EFH and Their Significance ................................. 66 (6) Direct Effects on Invertebrates and Their Significance .................................................... 69 (7) Direct Effects on Seabirds and Their Significance ........................................................... 70 Environmental Assessment for a USGS GOA Seismic Survey, 2011 Page iii Table of Contents (8) Indirect Effects on Marine Mammals, Sea Turtles, Seabirds, and Their Significance ................................................................................................................. 72 (9) Possible Effects on Subsistence Hunting and Fishing ...................................................... 72 (10) Cumulative Effects ......................................................................................................... 74 (11) Unavoidable Impacts ...................................................................................................... 78 (12) Coordination with Other Agencies and Processes .......................................................... 78 Alternative Action: Another Time .................................................................................................... 79 No Action Alternative ...................................................................................................................... 79 V. LIST OF PREPARERS ................................................................................................................................ 80 VI.LITERATURE CITED ................................................................................................................................ 81 Marine Mammals and Acoustics ...................................................................................................... 81 Sea Turtles, Seabirds, Fish, and Other ............................................................................................ 106 APPENDIX A: ACOUSTIC CALIBRATION AND MODELING OF SESIMIC ACOUSTIC SOURCES ON THE R/V LANGSETH (20072008) .................................................................................................... 117 1. Introduction ............................................................................................................................... 117 2. Modeling Langseth Airgun Arrays for Mitigation .................................................................... 117 3. Comparing Modeling with Measurements ................................................................................ 119 4. Conclusions ............................................................................................................................... 123 5. Literature Cited .......................................................................................................................... 123 APPENDIX B: REVIEW OF THE EFFECTS OF AIRGUN SOUNDS ON MARINE MAMMALS ......................... 124 1. Categories of Noise Effects ....................................................................................................... 124 2. Hearing Abilities of Marine Mammals ...................................................................................... 124 2.1 Toothed Whales (Odontocetes) ...................................................................................... 125 2.2 Baleen Whales (Mysticetes) ........................................................................................... 125 2.3 Seals and Sea Lions (Pinnipeds) .................................................................................... 126 2.4 Manatees and Dugong (Sirenians) ................................................................................. 126 2.5 Sea Otter and Polar Bear ................................................................................................ 127 3. Characteristics of Airgun Sounds .............................................................................................. 127 4. Masking Effects of Airgun Sounds ........................................................................................... 129 5. Disturbance by Seismic Surveys ..............................................................................................