Mortality is a demographic metric crucial for understanding the dynamics of endangered populations such as Cook Inlet beluga whales (CIBWs, Delphinapterus leucas), but patterns of mortality are currently not well understood for CIBWs, making decisions about recovery actions challenging. We combined long-term photo-ID data from approximately 420 individual belugas identified during the period 2005-2017 with stranding data from 95 dead belugas to identify patterns of mortality with respect to age, sex, geographic range, cause of death, and to estimate minimum mortality rates. Reported mortality was greatest for adults of reproductive age, followed by calves, with fewer subadults and no adults older than 49 years in the stranding data set despite lifespans of 70+ years reported in other beluga populations. Dead females and males were evenly represented. Live stranding was the predominant assigned cause of death but represented only similar to 33% of deaths of known cause. Causal factors for the majority of deaths and live strandings are unknown. Annual mortality estimated from reported carcasses relative to total population size averaged 2.2%. Our analysis advances our current understanding of mortality patterns in CIBWs but linking a greater proportion of carcasses to photo-ID individuals would further improve our understanding; we conclude with recommendations for achieving this.y

Vessel strikes, entanglement, poaching, intentional harassment, and invasive research are possible direct anthropogenic threats to the endangered Cook Inlet beluga whale, Delphinapterus leucas, population (CIBW) according to the CIBW Recovery Plan. Establishing the prevalence of such threats is necessary for understanding impact and monitoring future trends. We examined records of individual belugas photographed during 2005–17, along with stranding records during this time, to determine prevalence of scars indicative of anthropogenic trauma, and classified these scars according to their likely sources (e.g., entanglements, vessel strikes, puncture wounds, and research). In this combined dataset, 37.7% of 106 individuals had scars classified as either confirmed or possible anthropogenic origin. In the photo-ID records, 15% of individuals had signs of confirmed or possible entanglement, 14% had signs of confirmed or possible vessel strikes, 5% had signs of possible puncture scars, and 24% had research scars. Out of 33 necropsied belugas, 6% had scars from satellite tagging, 6% had signs of entanglement, 3% had possible signs of a vessel The designation under the U.S. Endangered Species Act (ESA) occurred in October 2008 (NOAA, 2008) and was preceded by a steep decline in the CIBW population during the 1990’s and a designation as “depleted” in 2000 under the Marine Mammal Protection Act (NOAA, 2000). An unsustainable level of hunting by Native Alaskans (Mahoney and Shelden, 2000) was thought to be the primary cause of the initial population decline. Cooperative agreements between NMFS and subsistence users suspended CIBW hunting after 2006 (NOAA, 2008). If subsistence hunting was the only factor limiting population growth, the population was expected to have recovered in the following decade. However, a survey by NMFS conducted in June 2018 found the strike, and 3% had possible signs of puncture scars. We also examined wound healing, reproduction, and survival of individuals with scars consistent with anthropogenic trauma. One important result from this work is that trauma from anthropogenic sources may take years to manifest. From our limited sample we cannot directly infer the population-level prevalence of anthropogenic trauma, but our assessment shows the source and prevalence in the sample; this is a preliminary step in understanding how anthropogenic trauma may be contributing to the population’s continued decline. population has continued to decline at a rate of about 2% per year since the ESA listing in 2008 (Wade et al.2). The reasons for this decline remain unknown. The CIBW Recovery Plan lists ten likely threats to CIBW recovery, including injury and death from anthropogenic activities (referred to collectively in the Plan as “unauthorized take,” although this category also includes NMFS authorized take for research). Unauthorized take is categorized as a threat of medium concern in the CIBW Recovery Plan, with the level of concern affected, in part, by uncertainties about magnitude and trend. Establishing a baseline estimate of the current magnitude of this threat is necessary for establishing and monitoring future trends. The shores of Cook Inlet are inhabited by most of Alaska’s human population and in2Wade, P. R., C. Boyd, K. E. W. Shelden, and C. L. Sims. 2019. Chapter 2: Group size estimates and revised abundance estimates and trend for the Cook Inlet beluga population. In K. E. W. Shelden, and P. R. Wade (Editors). 2019. Aerial surveys, distribution, abundance, and trend of belugas (Delphinapterus leucas) in Cook Inlet, Alaska, June 2018. AFSC Proc. Rep. 2019-09, 93 p. (https://apps-afsc.fisheries.noaa.gov/documents/ PR2019-09.pdf). Tamara L. McGuire is the Principal Investigator, along with co-investigators Amber D. Stephens and John R. McClung, on the Cook Inlet Beluga Whale Photo-ID Project, Anchorage, AK 99515 (email: tamaracookinletbeluga@gmail. com). Christopher Garner is with 673 CES/ CEIEC, Conservation Dept., Joint Base Elmendorf Richardson, AK 99506. Kathleen A. BurekHuntington is with the Alaska Veterinary Pathology Services, 23834 The Clearing Dr., Eagle River, AK 99577. Caroline E. C. Goertz is with the Alaska SeaLife Center, 301 Railway Ave., P.O. Box 1329, Seward, AK 99664. Kim E. W. Shelden is with the Marine Mammal Laboratory, Alaska Fisheries Science Center, NMFS, NOAA, 7600 Sand Point Way N.E., Seattle, WA 98115. Greg O’Corry-Crowe is with the Harbor Branch Oceanographic Institute, Florida Atlantic University, 5600 N U.S. Highway 1, Fort Pierce, FL 34946. Gina K. Himes Boor is with the Ecology Department, Montana State University, P.O. Box 173460, Bozeman, MT 597173460. Bruce Wright is with the Knik Tribe, P.O. Box 871565, Wasilla, AK 99654.

Beluga whales (Delphinapterus leucas) occur broadly throughout the polar and subpolar regions of the Northern Hemisphere, and as a whole, the species is of low conservation concern. However, some populations, including Alaska’s Cook Inlet beluga whales (CIBW), are in decline for reasons that remain poorly understood. Currently, information on population-specific reproductive parameters of CIBW is non-existent. To address this data gap, we examined long-term photo-identification data of CIBW for insight into the reproductive natural history of this endangered subarctic population. Data are from 438 photo-ID surveys conducted 2005–2017 and over 400 identified individuals, augmented with data from strandings, biopsies, and tagging. During the April–October ice-free field season, we observed neonates July–October but never April-June. We photo-documented three suspected births during July–September. Neonates were present in 30% of groups and encountered and comprised 2% of all belugas observed. Over the course of the 13-year study, the number of calves seen with an individual mother ranged from 1 to 5, with inter-birth intervals ranging from 2 to 13 years. This corresponds to rates of 0.08–0.38 calves per year per mother. Known-aged mothers ranged in age from 13 to 31 years. Skin color was not a reliable indicator of sexual maturity. Calves photographed alongside their mothers were estimated to be 1–8 years old, although most were 1–4 years old. Some mothers (6%) were accompanied by a neonate and an older calf. These summaries of observational data provide critical insight into CIBW reproductive natural history that will inform future population modeling and management decision-making.

Cook Inlet beluga whales (CIBWs;Delphinapterus leucas), are an isolated and declining endangered population in Alaska, USA. Their critical habitat has been broadly defined, with little empirical data on habitat use to direct management actions. This article examines data collected during surveys for a long-term photo-ID study to gain insight into the use of critical habitat by CIBW groups and individuals, with a focus on areas where belugas were observed feeding, calving, rearing young, and in transit. It also describes patterns of group distribution, size, and composition, according to sex and age class, in order to better understand how CIBWs are distributed throughout critical habitat during the ice-free season. The results are presented according to survey month and survey zone, so that patterns of habitat use are accessible in a useful format to aid managers in evaluations of how timing and location of human activities occurring in CIBW critical habitat may overlap with CIBW occurrence and use of these areas. There were 575 beluga groups encountered during 477 photo-ID surveys conducted in CIBW critical habitat 2005-2017. CIBW locations were mapped, and models were developed to test for temporal and spatial patterns. Approximately 400 individual whales were identified, and their sighting histories were compiled to examine residency and movement patterns. CIBWs were found seasonally in distinct areas, where they aggregate in large groups of both sexes and all age classes while rearing calves and feeding. These areas, and the general corridors connecting them, represent important beluga habitat that warrant focused management attention and protection efforts. Whales travelling among distinct areas of Cook Inlet increase their likelihood of exposure to multiple, localized threats. Habitat protection and the regulation of anthropogenic activities should consider cumulative effects of all activities in the range of CIBWs and their potential to affect the entire population. 1.2.3.4.5.