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Hours per day that southern Alaska resident killer whales were detected in Montague Strait, Hinchinbrook Entrance, and Resurrection Bay, Gulf of Alaska, June 2019 to May 2020. Gray bars represent daily hours with detections, blue line is a weekly rolling average. No data were available at Hinchinbrook Entrance from July 26th-September 27th, 2019 and May 30th-31st, 2020 and at Montague Strait from September 25th-26th, 2019.
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Killer whales (Orcinus orca) are top predators throughout the world’s oceans. In the North Pacific, the species is divided into three ecotypes—resident (fish-eating), transient (mammal-eating), and offshore (largely shark-eating)—that are genetically and acoustically distinct and have unique roles in the marine ecosystem. In this study, we examined...
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A longer Arctic open water season is expected to increase underwater noise levels due to anthropogenic activities such as shipping, seismic surveys, sonar, and construction. Many Arctic marine mammal species depend on sound for communication, navigation, and foraging, therefore quantifying underwater noise levels is critical for documenting change...
Citations
... For example, to ensure year-round data, recorders often have to be set to a duty cycle, therefore resulting in periods when data are missing. Deployments in the East, Northeast Offshore, and South (2018-2019) had duty cycles similar to those used elsewhere (Myers et al., 2021). In contrast, duty cycles used for the Northeast Inshore, West 1 and West 2 locations, and the other South deployment (2022-2023) included much longer periods when the recorder was off, which may have contributed to the lower detection rates in some of these data sets, as Riera et al. (2013) also suggest. ...
The distribution and occurrence of killer whales around Iceland are primarily studied in coastal herring grounds, with limited knowledge beyond these areas. This study employed opportunistic passive acoustic monitoring (PAM) data from four regions across Icelandic inshore and offshore waters to investigate killer whale distribution between 2018 and 2023. An automatic detector‐and‐classifier algorithm identified killer whale burst‐pulsed calls, manually confirmed by human observers. Killer whale calls were detected on a total of 59 of 3075 recording days over a broader geographic area than previously documented. Detections were spread throughout the years, and in some cases, potential feeding behavior could be inferred. In the south of Iceland, killer whales were detected throughout the winter period; their presence outside of the summer months was previously undocumented. In the west, daily occurrences differed between two locations, which may be linked to the distribution of herring. In the east and northeast, killer whales were detected in the summer months, aligning with the abundance of herring in these regions. This study highlights the importance of PAM for year‐round monitoring of killer whale occurrence in the North Atlantic and contributes to our understanding of how they may respond to potential changes in prey dynamics.
... Oil toxicity can also cause kidney abnormalities such as hypoadrenocorticism and adrenal toxicity, and respiratory diseases such as alveolar interstitial syndrome and pulmonary masses in marine animals, such as that reported with the Deepwater Horizon oil spill [82]. A massive mortality in the population of common Bottlenose dolphins in Louisiana (USA) by marine oil spills has been reported [83] and a long-term population monitoring study has been conducted on the decline in the number of killer whales (Orcinus orca) in Alaska following the Exxon Valdez oil spill [84]. Turtles, crocodiles, alligators, and sea snakes are also all vulnerable to the harmful effects of oil on the ground or in shallow waters. ...
A large volume of traditional crude oil is still transported through the ocean from production sites to utilization areas around the world. Unconventional petroleum products also cross pelagic natural habitats: for example, diluted bitumen from Canada's oil sands is transported through the Pacific coast to the USA and Asia. Oil and grease (O&G) concentrations in industrial wastewaters and the environment have been reported as rising, with increasing negative effects on the environment. The primary sources of O&G contaminations in aquatic and terrestrial environments are use of O&G in high-demand oil-processed foods, establishment and expansion of oil refinery and petrochemical plants around the world, and spills of O&G into environment during transportation. In most cases, O&G may be cleaned up by the environment's natural processes (such as photooxidation, biodegradation, and evaporation). The bulk oil is removed by naturally existing bacterial populations via one of the several oil weathering methods, which is why bioremediation has gained a lot of attention. Thus, with an ongoing need to evaluate the toxicological effects of chronic and disastrous petroleum spills on marine wildlife, several microorganisms capable of degrading O&G have been identified and may be potential candidates for bioaugmentation products. Therefore, this review focuses on the potential of using microbial candidates as an effective solution to remove the presence of O&G in various wastewaters and soil environments. The review also summarizes the current understanding of the extent and effects of O&G as well as hydrocarbon spills in aquatic and terrestrial environments, the function of microorganisms on degradation of these O&G, and current gaps in knowledge.
Graphical Abstract
... However, relative call type occurrence appears to vary little between years and killer whale call repertoires have been shown to be stable over decades Ford, 1991;Wellard et al., 2020). The stereotypy of killer whale calls, their long-term stability, and variations between ecotypes, populations, and social groups make these sounds very suitable for PAM methods, e.g., to study the spatial and temporal occurrence of different killer whale social groups (e.g., Yurk et al., 2010) and ecotypes (e.g., Myers et al., 2021;Rice et al., 2017;Riera et al., 2019). However, descriptions of the repertoires are lacking in several regions, including the Northeast Atlantic. ...
Killer whales ( Orcinus orca ) have group‐specific call repertoires that can be used to track groups and populations using passive acoustic monitoring. To provide a detailed description of the Icelandic killer whale repertoire and its variation, we analyzed acoustic data collected in five locations between 1985 and 2016. Calls were classified manually, and CART and random forest analyses were employed to validate the manual classification. A total of 91 call categories (including call types and subtypes) were defined. Most call categories were recorded in more than one location, with the highest proportion shared between herring grounds in Vestmannaeyjar (South) and Breiðafjörður (West). However, both locations included call categories that were not recorded elsewhere in Iceland. Recordings from past herring wintering grounds in eastern Iceland included few call categories that matched other locations. Sample sizes from Reykjanes (Southwest) and Skjálfandi (North) were small and did not include unique call categories. The relative occurrence of call categories in Vestmannaeyjar changed little over a 14‐year period (2002–2016), although shorter‐term changes between years were observed that appeared to correlate to changes in individuals identified. This comparison of acoustic repertoires provides valuable information on the social structure and movement patterns of herring‐eating killer whales around Iceland.
Top predators influence ecological communities in part through the prey they consume, which they often track through cycles of seasonal and geographic abundance. Killer whales are top predators in the marine ecosystem. In the North Pacific, they have diverged into three distinct lineages with different diets, of which the fish-eating type is most abundant. In this study, we examine the diet of the southern Alaska resident killer whale population across three major foraging aggregations. We take advantage of two unique sampling methods to reveal strong spatiotemporal patterns in diet from May through September. Chinook, chum, and coho salmon were each dominant in different locations and times, with substantial dietary contributions from Pacific halibut, arrowtooth flounder, and sablefish. The diverse, location-specific, and seasonal nature of the feeding habits of this marine top predator highlights the importance of diet sampling across broad spatiotemporal and population-level scales.
Understanding habitat use patterns of animal populations across space and time is fundamental to identifying ecological requirements, and informing threat mitigation and conservation strategies. Persistent data gaps tend to occur with cryptic species in difficult-to-access environments, where the use of appropriate monitoring tools is indispensable for detection. Three populations of threatened and endangered killer whales occur year-round in waters off British Columbia, Canada; however, their winter habitat use patterns are not well known. Here we quantify wintertime use of the northern Strait of Georgia by these sympatric killer whale populations, revealing the importance of this previously understudied region. Using a network of passive acoustic monitoring devices deployed over three winter periods, we examine site-specific and regional patterns of occurrence of Bigg’s, and Southern and Northern Resident killer whales. All three populations frequented these waters in nearly every month from November to April, and across all study years. Bigg’s killer whales were detected most frequently, followed by Southern Residents, then Northern Residents. Population-specific differences in site use was apparent, with Southern Resident detections occurring more often than expected off the southwest side of Texada Island, while Northern Residents appeared to favor the east side of Texada Island. Remarkably, the patterns of winter use we observe in this region by Resident killer whale populations have seemingly persisted for at least 50 years. Additionally, we evaluate and discuss the effect of using multiple simultaneous recorders to characterize habitat use patterns. Lastly, we present a data-driven approach for estimating acoustic residence time, describe inter-population differences in winter residency in the northern Strait of Georgia, and discuss implications for critical habitat designation. This study fills important knowledge gaps related to killer whale winter occurrence off western Canada, highlighting the significance of the northern Strait of Georgia for these at-risk populations.
Understanding the factors that cause endangered populations to either grow or decline is crucial for preserving biodiversity. Conservation efforts often address extrinsic threats, such as environmental degradation and overexploitation, that can limit the recovery of endangered populations. Genetic factors such as inbreeding depression can also affect population dynamics but these effects are rarely measured in the wild and thus often neglected in conservation efforts. Here we show that inbreeding depression strongly influences the population dynamics of an endangered killer whale population, despite genomic signatures of purging of deleterious alleles via natural selection. We find that the ‘Southern Residents’, which are currently endangered despite nearly 50 years of conservation efforts, exhibit strong inbreeding depression for survival. Our population models suggest that this inbreeding depression limits population growth and predict further decline if the population remains genetically isolated and typical environmental conditions continue. The Southern Residents also had more inferred homozygous deleterious alleles than three other, growing, populations, further suggesting that inbreeding depression affects population fitness. These results demonstrate that inbreeding depression can substantially limit the recovery of endangered populations. Conservation actions focused only on extrinsic threats may therefore fail to account for key intrinsic genetic factors that also limit population growth.
Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigate whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global dataset of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstruct demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We find a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.
