Submitted in support of the U.S. Navy’s 2018 Annual Marine Species Monitoring Report for the Pacific https://doi.org/10.25923/awmd‐rf62 Cetacean Monitoring in the Mariana Islands Range Complex, August‐September 2018 Marie C. Hill1,2, Allan D. Ligon3, Adam C. Ü4, and Erin M. Oleson2 1 Joint Institute for Marine and Atmospheric Research Research Corporation of the University of Hawaiʻi 1000 Pope Road, Honolulu, Hawaiʻi 96822, U.S.A. 2NOAA Fisheries Pacific Islands Fisheries Science Center 1845 Wasp Blvd. Building 176, Honolulu, Hawaiʻi 96818, U.S.A. 3301 W Briarcrest Dr., Erin, Tennessee 37061, U.S.A 4 PO Box 1329 Maple Falls, WA 98266, U.S.A. PIFSC Data Report DR‐19‐010. 22 pp. Issued 05 March 2019 Suggested citation: Hill M.C., A.D. Ligon, A.C. Ü, and E.M. Oleson. 2019. Cetacean Monitoring in the Mariana Islands Range Complex, August–September 2018. Prepared for the U.S. Pacific Fleet Environmental Readiness Office. Submitted in support of the U.S. Navy’s 2018 Annual Marine Species Monitoring Report for the Pacific This page intentionally left blanki. Submitted in support of the U.S. Navy’s 2018 Annual Marine Species Monitoring Report for the Pacific Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Service, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188) Washington, DC 20503. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To) 05-03-2019 Monitoring report August - December 2018 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER CETACEAN MONITORING IN THE MARIANA ISLANDS RANGE N62470-15-D-8006 COMPLEX, AUGUST-SEPTEMBER 2018 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Marie C. Hill Allan D. Ligon Adam C. Ü 5e. TASK NUMBER Erin M. Oleson 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION Joint Institute for Marine and Atmospheric Research, Research Corporation of REPORT NUMBER the University of Hawaiʻi, Honolulu, HI PIFSC Data Report DR-19-010 NOAA Fisheries, Pacific Islands Fisheries Science Center, Honolulu, HI 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) Commander, U.S.Pacific Fleet, 250 Makalapa Dr., Pearl Harbor, HI 11. SPONSORING/MONITORING AGENCY REPORT NUMBER 12. DISTRIBUTION AVAILABILITY STATEMENT Approved for public release; distribution is unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The Pacific Islands Fisheries Science Center’s (PIFSC) Cetacean Research Program (CRP) has conducted visual surveys for cetaceans in the waters surrounding Guam and the Commonwealth of the Northern Mariana Islands (CNMI) since 2010 as part of an ongoing effort to develop a record of cetacean occurrence in the region. During 24 August–9 September 2018, non-systematic visual surveys were conducted from small vessels off Saipan, Tinian, Aguijan, and Guam. A total of 1,168 km of trackline was surveyed and most was in Beaufort sea states of 2-4 (73%) and swell heights of 0-4 ft (71%). Twenty cetacean groups were encountered, resulting in the collection of 6,437 photos, 33 biopsy samples, and the deployment of 5 satellite tags. Five cetacean species were identified – spinner dolphin (Stenella longirostris), pantropical spotted dolphin (S. attenuata), bottlenose dolphin (Tursiops truncatus), short-finned pilot whale (Globicephala macrorhynchus), and sperm whale (Physeter macrocephalus). Spinner dolphins were the most frequently encountered species (n=9), followed by pantropical spotted dolphin (n=7), bottlenose dolphin (n=2), pilot whale (n=2), and sperm whale (n=1). Patterns of spatial use by these 5 cetacean species were similar to those described in previous years. Spinner dolphin encounters were in waters with bottom depths <100 m and within 3.5 km from shore. The median depth of all pantropical spotted dolphin encounter locations was 1,211 m; median distance from shore was 9.3 km. The depths of the bottlenose dolphin encounters were 64 m (at Marpi Reef) and 459 m (off Tinian), and the distances from shore were 16.8 km and 2.6 km, respectively. The two groups of short-finned pilot whales were encountered off Marpi Reef and off the west side of Tinian. The depths of the encounter locations were 920 m and 698 m, and the distances from shore were 21.0 km and 4.9 km, respectively. The sperm whale sighting (which also included 3 mother/calf pairs) was 10 km from the west side of Guam, over a bottom depth of 2,051 m. A total of 33 biopsy samples were collected: Standard Form 298 (Rev. 8-98) Prescribed by ANSI-Std Z39-18 Submitted in support of the U.S. Navy’s 2018 Annual Marine Species Monitoring Report for the Pacific spinner dolphin (n=6), pantropical spotted dolphin (n=7), bottlenose dolphin (n=2), short-finned pilot whale (n=15), and sperm whale (n=3). A total of 6,437 photos were taken: spinner dolphin (n=2,261), pantropical spotted dolphin (n=656), bottlenose dolphin (n=294), short-finned pilot whale (n=2,568), and sperm whale (n=658). In total, 5 satellite tags (3 location-only SPOT6, 2 location-depth SPLASH) were deployed on pilot whales to investigate individual movements and spatial use. Three satellite tags (2 SPOT6, 1 SPLASH) were deployed during an encounter off Marpi Reef on 26 August. Tag durations ranged from 8.9 to 122.7 d, during which the whales appeared to travel together and primarily moved within the 3-islands area but made excursions north to Anatahan and south to Rota and Guam. Two satellite tags (1 SPOT6, 1 SPLASH) were deployed during a short-finned pilot whale encounter off Tinian on 28 August, with a group different than that encountered on 26 August. Tag durations were 15.2 d and 14.6 d, during which the whales primarily stayed off Aguijan and the southern end of Tinian but also went south to Rota and offshore approximately 70 km to the west. On 5 September, the tagged whales from the two different encounters briefly crossed paths, with 2 tagged individuals within 200 m of one other. There were no encounters of baleen whales during the 2018 summer surveys. A total of 19 sea turtles (10 identified as green turtles (Chelonia mydas), the rest were unidentified) were observed. 15. SUBJECT TERMS Monitoring, marine mammals, toothed whales, sea turtles, vessel visual survey, satellite tagging, Mariana Islands Range Complex 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON ABSTRACT OF PAGES Department of the Navy UU 22 a. REPORT b. ABSTRACT c. THIS PAGE 19b. TELEPONE NUMBER (Include area code) Unclassified Unclassified Unclassified 808-471-6391 STANDARD FORM 298 Back (Rev. 8/98) Submitted in support of the U.S. Navy’s 2018 Annual Marine Species Monitoring Report for the Pacific Mission The Pacific Islands Fisheries Science Center’s (PIFSC) Cetacean Research Program (CRP) has been conducting visual surveys for cetaceans in the waters surrounding Guam and the Commonwealth of the Northern Mariana Islands (CNMI) as part of an ongoing effort to develop a record of cetacean occurrence in the region. Visual surveys have been conducted aboard small boats (7.6–12.2 m) since 2010 off the southernmost islands of the Mariana Archipelago (Saipan, Tinian, Aguijan, Rota, and Guam). These surveys include the collection of photographs for individual identification, tissue samples for genetic analysis of population structure, and the deployment of satellite tags for assessment of individual movements throughout the broader region. Funding for these surveys was provided in partnership between the Navy (U.S. Pacific Fleet Environmental Readiness Division) and PIFSC. Data sets from the small‐boat survey efforts are used to evaluate the distribution, stock structure, and movements of cetaceans within the study area. This report includes a summary of the most recent visual surveys that were conducted in the “summer” (August–September) of 2018. Methods Field Methods–Visual Surveys During August–September 2018, non‐systematic visual surveys for cetaceans were conducted from small vessels off Saipan, Tinian, Aguijan, and Guam. Surveys off Saipan, Tinian, and Aguijan were conducted using a 12.2‐m sport‐fisher with flying bridge and twin‐diesel inboard engines (Sea Hunter) and a 7.9‐m Regulator with twin 4‐stroke outboard engines (Regulator). Surveys off Guam were conducted aboard a 10‐m Grady White with twin outboard engines (No Quarter) and a 17.7‐m Riviera Sport Fisher with flying bridge and twin diesel inboard engines (Liquid Soul). Visual survey effort and vessel tracks were spread out from day to day to ensure broad survey coverage over a wide range of depths. Weather and sea conditions dictated the direction and scope of the survey effort. The survey vessels traveled at a speed of 15–26 km/h, depending on the size of the vessel and sea conditions. Four to 6 observers scanned for marine mammals with unaided eyes, collectively searching 360 degrees around the vessel. All cetacean groups sighted were approached for species confirmation, group size estimates, photo‐identification, and biopsy sampling. Satellite tagging operations were planned during encounters with all cetacean species except stenellid dolphins.