59909 Document Published / External 30990 PSD- Cetacean Research Program (CRP) Publications Portfolio Project Completed 2020-06 The Pacific Islands Fisheries Science Center conducted small-boat surveys for endangered Western North Pacific humpback whales off Saipan and neighboring islands in the Mariana Archipelago during the winter months of 2015 to 2019. A total of 42 non-calf whales and 14 calves were observed, and individual resight durations ranged from 1 to 10 d during the 10-18 d survey periods. Preliminary annual mark-recapture abundance estimates of humpback whales within the study area were obtained using photo-identification data collected during the surveys and were adjusted to account for calves. Yearly abundance estimates ranged from 34 (SE, 19; 95% CI, 12 to 92) whales in 2019 to 126 (SE, 44; 95% CI, 65 to 246) whales in 2017, with an average of 61 (SE, 13; 95% CI, 41 to 91) whales across all years. Density estimates were calculated by year for the full study area where surveys were conducted, as well as a truncated area where most of the survey effort and all of the humpback whale sightings occurred. Yearly density estimates for the truncated survey area ranged from 0.09 to 0.33 whales/km2, and the average density estimate across years was 0.16 whales/km2. Care should be taken in the interpretation of the density estimates as they may be biased given they were derived from mark-recapture abundance estimates that are likely associated with sampling biases and that are not spatially-explicit. They cannot be used to estimate humpback whale density throughout the Mariana Archipelago or beyond. Regardless, the study area off Saipan represents an important area for an endangered population of humpback whales that should be considered in protection and conservation efforts. Hill MC, Bradford AL, Oleson EM. 2020. Preliminary mark-recapture abundance estimates of humpback whales on a breeding area in the Mariana Archipelago. Pacific Islands Fisheries Science Center, PIFSC Administrative Report. H-20-07, 18 p. doi:10.25923/v3fd-yf59 10.25923/v3fd-yf59 Theme Megaptera novaeangliae Theme abundance Theme density Theme humpback whales Theme mark-recapture Theme photo-identification Spatial Mariana Archipelago Pacific Islands Fisheries Science Center Honolulu HI USA Administrative Report Acrobat Portable Document Format Published Author 2020 Person Hill, Marie C marie.c.hill@noaa.gov 1845 Wasp Blvd. Honolulu HI 96818 USA (808)725-5710 Co-Author 2020 Person Bradford, Amanda L amanda.bradford@noaa.gov https://orcid.org/0000-0002-3236-834X 1845 Wasp Blvd. Honolulu HI 96818 USA (808)725-5714 8:30 AM - 5:00 PM Co-Author 2020 Person Oleson, Erin M erin.oleson@noaa.gov 1845 Wasp Blvd. Honolulu HI 96818 USA (808)725-5712 9:00 a.m. - 5:00 p.m. Data Steward 2015 Person Hill, Marie C marie.c.hill@noaa.gov 1845 Wasp Blvd. Honolulu HI 96818 USA (808)725-5710 Distributor 2020 Organization Pacific Islands Fisheries Science Center PIFSC pifsc.info@noaa.gov https://ror.org/02apffz65 1845 Wasp Blvd. Honolulu HI 96818 USA 808-725-5360 https://www.pifsc.noaa.gov Pacific Island Fisheries Science Center homepage Online Resource 8:00 a.m. - 4:30 p.m. Metadata Contact 2020 Person Hill, Marie C marie.c.hill@noaa.gov 1845 Wasp Blvd. Honolulu HI 96818 USA (808)725-5710 Ground Condition 145.5 146 15.5 14.7 Three-Islands area (Saipan, Tinian, Aguijan), CNMI. Range 2015 2019 Unclassified Requestor will be asked to submit a request by email to Erin Oleson {erin.oleson@noaa.gov) or Marie Hill (marie.hill@noaa.gov) Requestor will be asked to submit a request by email to Erin Oleson {erin.oleson@noaa.gov) or Marie Hill (marie.hill@noaa.gov) Requestor will be asked to submit a request by email to Erin Oleson {erin.oleson@noaa.gov) or Marie Hill (marie.hill@noaa.gov) Requestor will be asked to submit a request by email to Erin Oleson {erin.oleson@noaa.gov) or Marie Hill (marie.hill@noaa.gov) None None https://repository.library.noaa.gov/view/noaa/24965 PDF PDF - Adobe Portable Document Format gov.noaa.nmfs.inport:59909 Marie Hill 2020-06-01T21:17:20 SysAdmin InPortAdmin 2026-05-26T15:20:59 2022-05-06 Pacific Islands Fisheries Science Center PIFSC 1845 Wasp Blvd. Honolulu HI 96818 USA 808-725-5300 https://www.pifsc.noaa.gov 8:00 a.m. - 4:30 p.m. 1001 Public No 2022-05-06 1 Year 2023-05-06