AbstractThere has been significant sea ice loss in the Arctic as a result of climate change, with measurable impacts on available habitat for ice-obligate marine mammals. Bearded seals (Erignathus barbatus) have a circumpolar distribution and primarily inhabit coastal areas of shallower depths with seasonal pack ice cover. However, there is limited information and no formal estimates on population abundance and densities of bearded seals within Canada. Here, we review historic field reports and publications from aerial surveys conducted from 1974 to 2022 to compile the density and abundance estimates of bearded seals across Canadian waters. Aerial surveys for marine mammals have been flown in several areas across the Canadian Arctic, including the Beaufort Sea (1974–2006), Canadian High Arctic (1979–2022), Baffin Bay-Davis Strait (1979–2014), and the Hudson Complex (1994–2017). After reviewing all published data sources, we report that the density of bearded seals in Canada were highest (and highly variable) in the Beaufort Sea (0.01–8.68 seals*km−2), then in Baffin Bay-Davis Strait (0.004–8.3 seals*km−2), and lowest and less variable inter-annually in the Hudson Complex (0.02 to 0.12 seals*km−2) at the time of these surveys. We also determined that bearded seals are more often found in areas of patchy ice cover (50–75%) with shallow water depths ≤ 500 m. Further, this review identifies regions within the Canadian Arctic and sub-Arctic that require updated aerial survey information. Quantifying the abundance and density estimates of bearded seals in Canada is essential for monitoring population status over time to better understand how this species is responding to environmental variation from anthropogenic activity and climate change.

AbstractObjectiveThe Fraser River in British Columbia, Canada, historically supported productive Indigenous, recreational, and commercial fisheries for Eulachon Thaleichthys pacificus. Although Eulachon spend most of their lives in the marine environment, they spawn in freshwater and it is hypothesized that habitat degradation in the Fraser River has contributed to population decline. A greater understanding of Eulachon life history strategies is necessary to develop species recovery strategies. The purpose of this study was to provide insight into population demographics, migration timing, residence time, travel speed and distance, and movement patterns of Eulachon traveling in the Fraser River by conducting index netting and acoustic telemetry.MethodsIn total, 244 Eulachon were acoustically tagged at the mouth of the Fraser River, and their movements were monitored using acoustic receivers in the lowermost 70 km of the Fraser River and in the Pitt River (a tributary to the Fraser River) over a 2‐year period.ResultTagged Eulachon displayed heterogeneous movement behaviors and a protracted migration period between February and May. Eulachon index gill netting revealed three discrete migration groups matching traditional ecological knowledge from Indigenous knowledge holders. There were shifts in population demographics, with sex ratios changing from predominately males to females throughout the migration. Residence time within the estuarine salt wedge and river was short. Upstream travel speeds varied significantly between sexes and slowed as fish traveled upstream.ConclusionOverall, Eulachon travel speeds, travel distances, and residence times, along with size and sex effects, provided insights into movement patterns. These results will increase our understanding of sex‐specific risks related to instream disturbance, harvest, and predation and will inform management decisions regarding protection of critical habitats. The observed patterns highlight the need for stock assessment methods to consider all discrete migration groups and will assist in prioritizing species recovery efforts.

Using DNA methylation profiles (n = 15,456) from 348 mammalian species, we constructed phyloepigenetic trees that bear marked similarities to traditional phylogenetic ones. Using unsupervised clustering across all samples, we identified 55 distinct cytosine modules, of which 30 are related to traits such as maximum life span, adult weight, age, sex, and human mortality risk. Maximum life span is associated with methylation levels in HOXL subclass homeobox genes and developmental processes and is potentially regulated by pluripotency transcription factors. The methylation state of some modules responds to perturbations such as caloric restriction, ablation of growth hormone receptors, consumption of high-fat diets, and expression of Yamanaka factors. This study reveals an intertwined evolution of the genome and epigenome that mediates the biological characteristics and traits of different mammalian species.

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.

Epigenetic approaches for estimating the age of living organisms are revolutionizing studies of long-lived species. Molecular biomarkers that allow age estimates from small tissue biopsies promise to enhance studies of long-lived whales, addressing a fundamental and challenging parameter in wildlife management. DNA methylation (DNAm) can affect gene expression, and strong correlations between DNAm patterns and age have been documented in humans and nonhuman vertebrates and used to construct "epigenetic clocks". We present several epigenetic clocks for skin samples from two of the longest-lived cetaceans, killer whales and bowhead whales. Applying the mammalian methylation array to genomic DNA from skin samples we validate four different clocks with median errors of 2.3-3.7 years. These epigenetic clocks demonstrate the validity of using cytosine methylation data to estimate the age of long-lived cetaceans and have broad applications supporting the conservation and management of long-lived cetaceans using genomic DNA from remote tissue biopsies.

AbstractBowhead whales (Balaena mysticetus) have adopted growth and reproductive strategies to survive in a challenging environment where no other mysticete whales reside. They grow slowly, become sexually mature at around 25 years (later than other mammals), and do not give birth until they have sufficient energy reserves for the best possible chance of survival of the calf to weaning and long-term survival of the mother. To compensate for late maturity and long inter-birth intervals, some seem to have the capability to live to 200+ years of age, making them the longest-lived mammal known to date. Bowhead whale males have large testes per body size, and it is hypothesized that the basic polygynandrous system of females and males mating with multiple partners per estrous cycle allows for males to not compete violently against each other. Instead, they use sperm competition by volume of sperm for enhanced capability to father as many offspring as possible. Also, as in right whales (Eubalaena spp.), the length of the penis is proportionally longer than those of balaenopterids. Details of sperm volume, potential variabilities of sperm viabilities, and actual paternities are unknown, but some patterns can be inferred from the closely related right whales with similar morphologies.

In conducting Arctic field research, hiring local field guides has long been a necessity for providing field teams with local knowledge and fundamental needs of boat operation and navigation, general field logistics/safety, and traditional ecological knowledge (TEK) of local animal distribution and natural history. As new threats to Arctic wildlife emerge and as field research methods evolve, including local Inuit as long-standing members of research teams has provided additional collaborative benefits through expanded local knowledge, greater efficiency of data collection, and longer temporal sampling which provides the opportunity to study uncommon events. We describe the collaboration between southern-based scientists and local Inuit from the community of Pangnirtung, Nunavut, to conduct field research on marine mammals in Cumberland Sound from 1997 to 2021. Through a keen interest in marine mammal field research, Inuit partners in Pangnirtung have become highly proficient in all aspects of sample and data collection and have received advanced technical training to allow for an expanded role in achieving research objectives. This expanded role includes running field research operations independently, as well as the extensive use of drones to capture photographs of whales for the purposes of photographic-identification and to record behavior. Collaboration with local Inuit also provides benefits through employment opportunities, development of technical skills, and opportunities to actively participate in research that aims to conserve culturally important local wildlife populations.

Effective management of animal populations requires knowledge of life history parameters and estimates of population abundance. One method commonly used to estimate abundance is capture–recapture analyses of photographs. Small, relatively inexpensive, rotary-wing drones have become an effective platform for obtaining high-quality aerial photographs of whales. To conduct capture–recapture analyses the animal needs to be defined as marked or unmarked and the photographs must be of high quality. While a system for scoring quality and markedness has previously been developed for bowhead whales (Balaena mysticetus Linnaeus, 1758) ( Rugh et al. 1998 . Rep. int. Whal. Commn. 48: 501–512), a revised scoring system was needed to incorporate increased information in photographs taken by drones. We present a revised scoring system that enlarges two of the previously defined areas of the whale examined for markings and incorporates smaller markings into the definition of marked whales. We scored 30 whales using the previous criteria and the revised criteria developed in this paper. More whales were identified as marked (23%) and mark scores were higher for 30% of the zones scored using the new system. Increasing the number of marked whales during capture–recapture studies increases the precision of estimated parameters and permits us to make those estimates with smaller samples of photographs.

AbstractFor the management of Coastal Cutthroat Trout Oncorhynchus clarkii clarkii, resource managers require abundance estimates and demographic structure of juvenile emigrants. However, Coastal Cutthroat Trout research and monitoring have been confounded by the variability in assessment approaches and ecological plasticity of the subspecies. The primary purpose of this study is to help address this current Coastal Cutthroat Trout fisheries management issue by conducting a synthesis of juvenile emigration studies and proposing solutions that should be considered by resource managers when designing juvenile emigration studies. A total of 100 studies conducted in British Columbia and Washington since the 1970s, representing 1,100 annual estimates, were reviewed. The results of this review highlighted inconsistencies in study timing, biological data collection, juvenile emigrant life stage assignments, species identification, and ecotype assumptions. Solutions to address these inconsistencies include increased recognition of juvenile emigrant studies targeting Coastal Cutthroat Trout, strengthened partnerships and data sharing between management agencies, implementation of a life stage assignment standard for juvenile emigration studies, implementation of a field‐based and genetic classification model to quantify study‐specific identification error rates of juvenile emigrants, and genetic research to determine ecotype expression at the population and individual scales. We highlight the practical issues related to juvenile emigration studies and provide recommendations for management actions to account for the great plasticity in Coastal Cutthroat Trout behavior across the subspecies’ range.