Population monitoring studies of harbor seals in Glacier Bay National Park, Alaska, have spanned five decades from the 1970’s to the present (Streveler 1979; Calambokidis et al. 1987; Mathews & Pendleton 2006; Womble al. 2010; Womble et al. 2020; Womble et al. 2021), representing one of just a few sites in in Alaska where such long-term monitoring effort exists. Monitoring methods for harbor seals at terrestrial sites have remained consistent since 1992 allowing for quantifying distribution, abundance, and trend of harbor seals in Glacier Bay National Park. This file includes data includes count data of harbor seals from digital photographs collected during aerial photographic surveys conducted in Glacier Bay National Park & Preserve in southeastern Alaska to assess the distribution, abundance, and trend of harbor seals at terrestrial and glacier ice sites (McBride Inlet and Tarr Inlet) from 2004 to 2023. Aerial photographic surveys were conducted from May-September, with most surveys occurring during May-June (pupping period) and July-September (molting period). Replicate aerial surveys (2-4 surveys during pupping and molting period) were conducted to increase precision in the trend estimates of harbor seals. If it was not possible to complete at least 4 replicate surveys on different days during one tidal cycle, then surveys were attempted during the second low tidal cycle of the month, weather permitting. From 2004-2025 this project was led by Jamie N. Womble (National Park Service), please contact Jamie if you have questions regarding these data, at jamienwombleak@gmail.com. Please see associated publications for more details. Womble, J.N., Williams, P.J., McNabb, R., Prakash, A., Gens, R., Sedinger, B. and Acevedo, C. (2021). Harbor Seals as Sentinels of Ice Dynamics in Tidewater Glacier Fjords. Frontiers in Marine Science, 8, pp.1-16. https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.634541/full Blanchet, M.A., Vincent, C., Womble, J., Steingass, S. and Desportes, G., (2021). Harbour Seals: Population Structure, Status, and Threats in a Rapidly Changing Environment. In Oceans (Vol. 2, No. 1, pp. 41-63).https://www.mdpi.com/2673-1924/2/1/3 Womble, J.N., Ver Hoef, J.M, Mathews, E.A., Gende, S.M. (2020). Calibrating and adjusting counts of harbor seals in a tidewater glacier fjord to estimate abundance and trends 1992-2017. Ecosphere 11(4), p.e03111. https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3111 Womble, J.N. 2012. Foraging ecology, diving behavior, and migration patterns of harbor seals (Phoca vitulina richardii) from a glacial fjord in Alaska in relation to prey availability and oceanographic features. Ph.D. Dissertation. Oregon State University, Corvallis, Oregon. Blundell, G.M., Womble, J.N., Pendleton, G.W., Karpovich, S.A., Gende, S.M., Herreman, J.K. (2011) Use of glacial ice and terrestrial habitats by harbor seals in Glacier Bay, Alaska: costs and benefits. Marine Ecology Progress Series 429:277- 290. https://www.int-res.com/articles/meps_oa/m429p277.pdf Allen, S.G., Brown, E., Faulkner, K., Gende, S.M., Womble, J. N. (2011) Conserving pinnipeds in Pacific Ocean parks in response to climate change. Park Science 28:48-52. https://www.researchgate.net/profile/Jamie-Womble/publication/258407609_Conserving_pinnipeds_in_Pacific_Ocean_parks_in_response_to_climate_chnage/links/0f3175372b3ec3667c000000/Conserving-pinnipeds-in-Pacific-Ocean-parks-in-response-to-climate-chnage.pdf Womble, J.N., Pendleton, G.W., Mathews, E.A., Blundell, G.M., Bool, N.M., Gende, S.M. (2010) Harbor seal decline continues in the rapidly changing landscape of Glacier Bay National Park, Alaska, 1992-2008. Marine Mammal Science 26:686-697https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2009.00360.x?msockid=14da1e5b94b961b802740be595036098 Womble, J.N., Pendleton, G.W., Mathews, E.A., Gende S.M. (2015). Status and trend of harbor seals at terrestrial sites in Glacier Bay National Park from

This dataset provides counts of harbor seals from aerial surveys over Lake Iliamna, Alaska, USA. The data have been collated from three previously published sources (Mathisen and Kline 1992; Small 2001; ABR Inc. Environmental Research and Services 2011) and newly available data from the NOAA Alaska Fisheries Science Center and the Newhalen Tribal Council. The survey years range between 1984 and 2013. Counts are reported as summed totals across all identified waypoints in the lake for each survey date. The NOAA National Marine Mammal Laboratory (NMML) (Alaska Fisheries Science Center, Seattle, Washington, USA) conducted aerial surveys of Iliamna Lake between 2008 and 2013. Surveys were conducted as part of annual harbor seal survey effort and in collaboration with local community participants and researchers at the University of Alaska. Surveys were flown using high wing, twin engine aircraft (Aero Commander 680, 690 or a de Havilland Twin Otter). Survey altitude was generally 330 m and at an aircraft speed of 120 kts. Surveys were performed seasonally for most years between 2008 and 2013. Surveys were timed so that one survey was conducted while the lake was mostly frozen (Late March/early April), one during pupping (mid July), and often several during the August molt, when the greatest number of seals typically haul out on shore. Surveys were flown, weather allowing, in the mid- to late-afternoon, when the number of seals hauled out was expected to be highest. Aircraft flight track was recorded by GPS and all seals sighted were digitally photographed using a high resolution digital SLR camera with a telephoto zoom lens (up to 400mm). Time, date, latitude, longitude, and altitude were automatically saved into the image metadata or georeferenced post survey using the GPS track and software. The total number of seals hauled out were counted from the digital photographs and recorded for each identified site. Pups were determined by their smaller size, and close proximity (less than 1 body length; either nursing or laying right next) to a larger seal. Pups were no longer recorded beyond about mid-August when many have been weaned and cannot reliably be distinguished from other non-adult seals. In 2009, a collaborative effort between NMML and researchers from the Newhalen Tribal Council (Newhalen Tribal Council 2009) provided 10 additional surveys and similar techniques were used. The raw survey count data from these surveys was provided to NMML. Aerial surveys were authorized under a Marine Mammal Protection Act General Authorization (LOC No. 14590) issued to the NMML. Between 2005 and 2007, ABR, Inc. Environmental Research and Services conducted a series of aerial surveys for harbor seals in Iliamna Lake (ABR Inc. Environmental Research and Services 2011). In addition, earlier counts from surveys conducted by ADFG (Small 2001) and a 1991 census by Mathisen and Kline (Mathisen and Kline 1992) were incorporated into the dataset to expand the historical reach. Geographic coordinates were provided (or, when not provided, determined based on descriptions or physical maps) for each survey site and these sites were compared and merged with locations identified by NMML. In some cases, sites in very close geographic proximity were combined into a single site. The iliamna_totalcounts file provides counts (n=96) and observed weather conditions for each survey date. Both total number of adult seals (adulttotal) and total number of identified pups (puptotal) are provided when available. puptotal is recorded as NA when adults and pups were not distinguished. In these cases, the adulttotal value is presumed to include pups. In addition to the seal count information, each record includes observed weather variables (airtemp (in ranges of degrees F), windspeed (in ranges of miles per hour), winddirection (cardinal), and descriptive categories for skycondition and precip). The datetime values correspond to local Alaska time.