Biology subjects

Boveng, P. L.

Publications and source records attributed to Boveng, P. L..

4 recordsLinked to original sources

bioRxiv2026

Abundance and distribution of ice-associated seals in the western Bering Sea and Sea of Okhotsk, 2012-2013

In the springs of 2012-2013, Russian Federation scientists conducted aerial surveys of ice-associated seals (including bearded, ribbon, ringed, and spotted seals) in the Sea of Okhotsk and in Russian waters of the western Bering Sea. These instrument-based surveys used a combination of thermal imaging and digital photography to detect and photograph seals basking on sea ice. Initial estimates of seal distribution and abundance from these surveys have been published in Russian journals, but did not make adjustments for observation error. In this paper, we reanalyze these data with the goal of producing spatially explicit estimates of seal abundance that properly account for incomplete detection and species classification errors. Our analysis used estimated relationships between seal abundance and habitat variables to predict abundance in unsurveyed locations, and auxiliary data on detectability to model the observation process. Under this framework, we estimated that in 2012 there were approximately 185,330 bearded seals, 68,564 ribbon seals, 272,609 ringed seals, and 226,003 spotted seals in the western Bering Sea; in 2013, these numbers were 144,105, 39,435, 203,130, and 90,501, respectively. In the Sea of Okhotsk, estimated abundance was 218,740 bearded seals, 221,228 ribbon seals, 179,893 ringed seals, and 169,870 spotted seals (2013 only). These are the first credible estimates of ice-associated seals in the Okhotsk and western Bering Seas, and should be useful for population management and for measuring how density and distribution change as a function of decreasing Arctic sea ice. Declines in seal estimates in the western Bering Sea from 2012 to 2013 mirror patterns observed in the eastern Bering Sea during concurrent U.S. surveys and could represent a decrease in abundance or a substantial decrease in pupping and molting activity.

ecology↗

bioRxiv2026

Abundance and trends of harbor seals (Phoca vitulina richardii) in Alaska, 1996-2023

Pacific harbor seals (Phoca vitulina richardii) were surveyed throughout their range along Alaska coasts over a 28-year period. Twelve management stocks, delineated on the basis of evidence for demographic independence, were monitored for abundance and trends. We employed a two-stage Bayesian hierarchical analysis that integrated aerial survey counts with satellite-linked bio-logger haul-out timelines to account for the proportion of seals in the water and not visible to survey observers and cameras. Overall, harbor seals were abundant (201,122 seals in 2023) but, during the span of our study the population (stock) trends varied. The first half of our study was characterised primarily by growth, with a peak abundance of approximately 225,000 seals in 2015. Since then trends have been variable, with some stocks (e.g., Bristol Bay) showing continued growth while others (e.g. Prince William Sound, South Kodiak) declined. The recent regional declines coincided with observed climate anomalies (e.g., marine heatwaves) and the rapid retreat of tidewater glaciers. Our results provide a basis for managing this species in Alaska, which is protected under the Marine Mammal Protection Act; a vital nutritional and cultural resource for Alaska Native communities; and an important sentinel of change in the Northeast Pacific marine ecosystem.

ecology↗

bioRxiv2024

Abundance and distribution of ringed and bearded seals in the Chukchi Sea: a reference for future trends

Ringed (Pusa hispida) and bearded (Erignathus barbatus) seals are vulnerable to decreasing sea ice habitat in the rapidly warming Arctic. In April and May of 2016, we conducted an aerial survey over the ice-covered areas of the Chukchi Sea using thermal and color cameras to detect and count these seals on sea ice. We related the seal counts to environmental variables, and used the relationships to estimate the species distributions and abundance throughout the Chukchi Sea. We accounted for incomplete detection due to seals missed by sensors or image processing errors, behavioral responses to aircraft, or incomplete availability (i.e. seals that are in water or in snow dens on the ice, called lairs). For the latter, we used wet/dry records from satellite-linked bio-loggers, and remotely sensed snow melt dates to estimate the proportion of ringed seal individuals that were visible on ice for each day and location surveyed. To our knowledge, this is the first study where use of lairs by ringed seals has been formally addressed while estimating abundance from aerial surveys. Ringed seal abundance was estimated as [Formula] = 592,577 (95% CI: 478,448-733,929), with highest densities near Kotzebue Sound, Alaska, USA. Bearded seal abundance was estimated as [Formula] = 147,421 (95% CI: 114,155-190,380), with highest densities in broken pack ice near Bering Strait. The influence of environmental variables, such as snow depth and ice type, was consistent with prior studies of the species natural history, particularly ringed seals preference for snow of adequate depth for lairs. Our study provides the first comprehensive abundance estimates for ringed and bearded seals in the Chukchi Sea and establishes a reference for monitoring how their populations respond to Arctic warming.

ecology↗

bioRxiv2022

Haul-out behavior and aerial survey detectability of seals in the Bering and Chukchi seas

Ice-associated seals rely on sea ice for a variety of activities, including pupping, breeding, molting, and resting. In the Arctic, many of these activities occur in spring (April - June) as sea ice begins to melt and retreat northward. Rapid acceleration of climate change in Arctic ecosystems is therefore of concern as the quantity and quality of suitable habitat is forecast to decrease. Improved estimates of seal population abundance are needed to properly monitor the impacts of these changes over time. In this paper, we use hourly percent-dry data from satellite-linked bio-loggers deployed between 2005 and 2021 to quantify the proportion of seals hauled out on ice. This information is needed to accurately estimate abundance from aerial survey counts of ice-associated seals (i.e., to correct for the proportion of animals that are in the water while surveys are conducted). In addition to providing essential data for survey availability calculations, our analysis also provides insights into the seasonal timing and environmental factors affecting haul-out behavior by ice-associated seals. We specifically focused on bearded (Erignathus barbatus), ribbon (Histriophoca fasciata), and spotted seals (Phoca largha) in the Bering and Chukchi seas. Because ringed seals (Phoca (pusa) hispida) can be out of the water but hidden from view in snow lairs analysis of their availability to surveys requires special consideration; therefore,they were not included in this analysis. Using generalized linear mixed pseudo-models to properly account for temporal autocorrelation, we fit models with covariates of interest (e.g., day-of-year, solar hour, age-sex class, wind speed, barometric pressure, temperature, precipitation) to examine their ability to explain variation in haul-out probability. We found evidence for strong diel and within-season patterns in haul-out behavior, as well as strong weather effects (particularly wind and temperature). In general, seals were more likely to haul out on ice in the middle of the day and when wind speed was low and temperatures were higher. Haul-out probability increased through March and April, peaking in May and early June before declining again. The timing and frequency of haul-out events also varied based on species and age-sex class. For ribbon and spotted seals, models with year effects were highly supported, indicating that the timing and magnitude of haul-out behavior varied among years. However, we did not find broad evidence that haul-out timing was linked to annual sea-ice extent. Our analysis emphasizes the importance of accounting for seasonal and temporal variation in haul-out behavior, as well as associated environmental covariates, when interpreting the number of seals counted in aerial surveys.

ecology↗