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Wildlife researchers need to understand the effects of biotelemetry tags in order to better weigh benefits versus risks. We describe tag‐site healing and pathology of three beluga whales, Delphinapterus leucas, found dead in Alaska. The tags were secured with two or three nylon rods that pierced the dorsal ridge, and one beluga also had a LIMPET tag. The tag wounds in one Cook Inlet beluga featured a normal healing response with minimal inflammation ~12 years posttagging. Photo‐ID studies of another Cook Inlet beluga demonstrated degeneration of the tag wounds over several years. It died ~12.8 years posttagging of bronchopneumonia and septicemia due to Staphylococcus aureus that also infected the tag wound. A Bristol Bay beluga died 4 months posttagging. Although it may have been predated by a killer whale attack, Orcinus orca, the tag site was inflamed and infected with Streptococcus uberis which spread to an abscessed lymph node. To reduce the risk of infection, researchers should adopt strict sterilization protocols for all implanted parts of tags and continue research into improved tagging methods. Clinical and behavioral assessment of potential preexisting conditions before tag deployment, as well as posttag monitoring, could help reduce tag‐associated mortality and identify immediate impacts and mortality. [ABSTRACT FROM AUTHOR]

Fishery observer records from 2001 through 2016 were examined to document interactions, injuries, and mortalities of killer whales (Orcinus orca) associated with fishing operations in Alaska. Although widespread throughout Alaska, the highest numbers of such events occurred in the southeastern Bering Sea. Killer whales of the resident ecotype feeding on catch or discarded catch and fishermen using whale deterrence measures represented 96% (number of interactions [n]=3110) of all interactions examined in this study (n=3245). We found that 87% (n=2817) of all interactions occurred during longline operations. Both minor and serious injuries were documented. Twenty-seven killer whales were reported dead, but additional mortalities are assumed. Most whales killed were residents; however, 3 transient whales were also taken. Because killer whale populations are relatively small, a low level of mortality may significantly affect populations, especially if multiple sympatric stocks are shown to exist. Given the long history (i.e., over 6 decades) that Alaska killer whales have had with fishing operations, it is likely that these interactions will continue. [ABSTRACT FROM AUTHOR]

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 the year-round distribution of killer whales in the northern Gulf of Alaska from 2016 to 2020 using passive acoustic monitoring. We further described the daily acoustic residency patterns of three killer whale populations (southern Alaska residents, Gulf of Alaska transients, and AT1 transients) for one year of these data. Highest year-round acoustic presence occurred in Montague Strait, with strong seasonal patterns in Hinchinbrook Entrance and Resurrection Bay. Daily acoustic residency times for the southern Alaska residents paralleled seasonal distribution patterns. The majority of Gulf of Alaska transient detections occurred in Hinchinbrook Entrance in spring. The depleted AT1 transient killer whale population was most often identified in Montague Strait. Passive acoustic monitoring revealed that both resident and transient killer whales used these areas much more extensively than previously known and provided novel insights into high use locations and times for each population. These results may be driven by seasonal foraging opportunities and social factors and have management implications for this species. [ABSTRACT FROM AUTHOR]

Killer whales occur in the Arctic but few data exist regarding the ecotypes present. The calling behavior differs among ecotypes, which can be distinguished based on pulsed call type, call rate, and bandwidth. In this study, a passive acoustic recorder was deployed 75 km off Point Hope, Alaska, in the southeastern Chukchi Sea to identify which ecotypes were present. A total of 1323 killer whale pulsed calls were detected on 38 of 276 days during the summers (June–August) of 2013–2015. The majority of calls (n = 804, 61%) were recorded in 2013 with the most calls recorded in July (76% of total calls). The calls were manually grouped into six categories: multipart, downsweep, upsweep, modulated, single modulation, and flat. Most detections were flat (n = 485, 37%) or multipart calls (n = 479, 36%), which contained both high and low frequency components. Call comparisons with those reported in the published literature showed similarities with other transient populations in fundamental frequency contour point distribution and median frequency. This study provides the first comprehensive catalog of transient killer whale calls in this region as well as reports on previously undescribed calls. [ABSTRACT FROM AUTHOR]

Killer whales (Orcinus orca) are highly social and occasionally gather in large aggregations that reach 150 individuals. During 338 encounters with Southern Alaska resident killer whales, we collected 1,352 hr of behavioral data to assess the probability of various behaviors based on season, number of pods present, presence of rarely sighted pods, and number of mitochondrial DNA haplotypes present. A binomial generalized linear model was used to estimate the role of these factors in the probability of four behaviors, foraging, resting, socializing, and traveling. The presence of "rarely sighted" pods (sighted in <5% of encounters) significantly increased probability of social behavior, and significantly decreased probability of resting. The number of pods present also significantly increased probability of increased social behavior. The presence of rarely sighted pods and the number of pods present did not have a significant interaction. Ordinal day and number of mitochondrial DNA haplotypes appears to not have changed the probability of any behavior. Foraging remained the predominant behavior throughout all factors. The concurrent increase in social behavior and decrease in resting behavior with rarely sighted pods present implies an unusually high importance of social behavior in the lives of resident killer whales. [ABSTRACT FROM AUTHOR]

Dietary specialization has led to the origin of several ecotypes of killer whales (Orcinus orca). Comparing the feeding habits of different populations within an ecotype is valuable for understanding the evolution of foraging strategies. In this study we investigated the diet of fish-eating killer whales in the Northwest Pacific Ocean (Avacha Gulf, Kamchatka) and compared it to the published data on Northeast Pacific fish-eating killer whales. We collected prey fragments (N = 141) after hunting events in the summer seasons of 2011–2016 and determined the species of prey. Killer whales fed mainly on various species of Pacific salmon in Avacha Gulf. Coho salmon (Oncorhynchus kisutch) (56% of samples) and chum salmon (O. keta) (31% of samples) predominated in the diet. The results are comparable to the peculiarities of the fish-eating killer whale diet in the Northeast Pacific where killer whales prefer Chinook salmon (O. tshawytscha) most of the summer but shift toward coho and chum in late summer. Avacha Gulf could be an area where killer whales come to hunt coho similar to Prince William Sound in Alaska where killer whales prefer coho to other salmon species. We found significant differences in the diet between sex-age categories. Females (N = 42) and juveniles (N = 15) were more selective and hunted mainly coho while males (N = 53) hunted chum equally to coho. Like Chinook in British Columbia, coho in Kamchatka has a prolonged spawning period. Coho is the most nutritious after Chinook. Coho's prolonged abundance and nutritional value probably make it preferable to killer whales especially females. [ABSTRACT FROM AUTHOR]

A mature, adult female, offshore killer whale (Orcinus orca) was stranded deceased in Portage Bay, Alaska, in October 2015. Full necropsy examination with histopathology was performed. Consistent with previous studies of offshore killer whales, and thought to be a result of their unique elasmobranch diet, all the teeth were significantly abraded and almost flush with the gingival margin. Age was estimated at 30–35 years based on annuli and growth arrest lines in a remaining tooth. The dentate portion of the mandibles were excised en bloc and frozen until imaging could be completed. Radiography and computed tomography revealed lesions consistent with severe abrasion, pulp exposure and evidence of endodontic and/or periodontal disease in nine of the 15 mandibular teeth present (60.0%). Only five (33.3%) teeth were suspected to have been vital at the time of death based on imaging. Lesions were more severe rostrally, with the caudal teeth less affected. Autolysis precluded gingival histopathology and no teeth were analyzed histologically. Necropsy examination revealed a likely multifactorial cause of death, with most significant lesions including the severe chronic periodontal/endodontic disease with abrasion, inanition and emaciation with possible cardiovascular disease. This case highlights the importance of imaging in evaluating periodontal and endodontic status, especially post mortem when other tissues are no longer available, and demonstrates that periodontal and endodontic disease occur naturally in this species and can be a significant cause of morbidity in mature free-ranging killer whales of the offshore ecotype. [ABSTRACT FROM AUTHOR]

During 1985–1990, two groups of killer whales in Prince William Sound, Alaska, experienced unusually high rates of mortality, while seven others did not. Those affected were AB pod, part of the southern Alaska population ofresident(fish-eating) killer whales, and the AT1transient(marine mammal–eating) group, a very small, reproductively isolated population that last reproduced in 1984. In 1985–1986, several AB pod members were shot by fishermen defending their catch from depredation, which explains some of the deaths. Understanding the other deaths is complicated by theExxon Valdezoil spill (March 1989) and uncertainties about the causes and times of the deaths. For AB pod, possible factors involved in the post-spill mortalities are delayed effects of bullet wounds, continued shooting, oil exposure, and consequences of being orphaned. For the AT1 group, possible factors are oil exposure, small population size, old age, and high-contaminant burdens. An analysis of possible effects of inhalation of volatile organic compounds, contact with the oil slick, and ingestion of oil with water or prey did not reveal route(s) of exposure that could explain the mortalities. The cause(s) of the killer whale deaths recorded following the oil spill remain uncertain. [ABSTRACT FROM AUTHOR]

Two sympatric populations of "transient" (mammal-eating) killer whales were photo-identified over 27 years (1984-2010) in Prince William Sound and Kenai Fjords, coastal waters of the northern Gulf of Alaska (GOA). A total of 88 individuals were identified during 203 encounters with "AT1" transients (22 individuals) and 91 encounters with "GOA" transients (66 individuals). The median number of individuals identified annually was similar for both populations (AT1=7; GOA=8), but mark-recapture estimates showed the AT1 whales to have much higher fidelity to the study area, whereas the GOA whales had a higher exchange of individuals. Apparent survival estimates were generally high for both populations, but there was a significant reduction in the survival of AT1 transients after the Exxon Valdez oil spill in 1989, with an abrupt decline in estimated abundance from a high of 22 in 1989 to a low of seven whales at the end of 2010. There was no detectable decline in GOA population abundance or survival over the same period, but abundance ranged from just 6 to 18 whales annually. Resighting data from adjacent coastal waters and movement tracks from satellite tags further indicated that the GOA whales are part of a larger population with a more extensive range, whereas AT1 whales are resident to the study area. [ABSTRACT FROM AUTHOR]

The article discusses a research study on killer whales Orcinus orca at Unimak Island, Alaska and their predation and prolonged feeding on submerged carcasses. Researchers conducted a 4-year time series of observations on the feeding and foraging behavior of more than 150 transient killler whales and their predatory attacks on gray whale Eschrichtius robustus where groups of 3 killer whales drown their prey and kill them in waters 15-75 meters deep. Results indicated that carcasses left by killer whales were revisited and fed on after several days while pieces floating onshore were consumed by brown bears Ursus arctos and those in deep waters consumed by Somniosus pacificus or sleeper sharks.

We used photographic mark-recapture methods to estimate the number of mammal-eating “transient” killer whales using the coastal waters from the central Gulf of Alaska to the central Aleutian Islands, around breeding rookeries of endangered Steller sea lions. We identified 154 individual killer whales from 6,489 photographs collected between July 2001 and August 2003. A Bayesian mixture model estimated seven distinct clusters (95% probability interval = 7–10) of individuals that were differentially covered by 14 boat-based surveys exhibiting varying degrees of association in space and time. Markov Chain Monte Carlo methods were used to sample identification probabilities across the distribution of clusters to estimate a total of 345 identified and undetected whales (95% probability interval = 255–487). Estimates of covariance between surveys, in terms of their coverage of these clusters, indicated spatial population structure and seasonal movements from these near-shore waters, suggesting spatial and temporal variation in the predation pressure on coastal marine mammals. [ABSTRACT FROM AUTHOR]

1. During the past 15–20 years, sea otters Enhydra lutris in the Aleutian Islands, Alaska, USA, experienced a drastic decrease in population size. It has been hypothesized that an increase in killer whale Orcinus orca predation was the primary cause of this decline. 2. Causation of the decline by increased killer whale predation is now considered a textbook case of top-down predator control. The purpose of this review is to re-evaluate the evidence for killer whale predation and to review evidence for alternative causes. 3. The killer whale predation hypothesis is based on three lines of evidence: (i) there was an increase in the number of observed killer whale attacks on sea otters during the 1990s, coincident with a decline in sea otters, (ii) sea otter populations did not decline in areas considered inaccessible to killer whales, while they declined in adjacent areas considered accessible to killer whales, and (iii) the estimated number of attacks necessary to account for the rate of decline is similar to the observed number of attacks. Our re-evaluation indicates that although the killer whale hypothesis is by no means disproved, the supporting data are limited and inconclusive. 4. Increases in shark populations in the Aleutian Islands concurrent with the sea otter population declines indicate the need for further research into the role of alternative marine predators in the population decline. 5. High contaminant levels observed in sea otters in the Aleutian Islands warrant further investigation into the impact of these toxins on sea otter health and vital rates, and their possible role on the population decline. 6. Disease has not been ruled out as a significant contributor to the population decline, particularly in the early stages of the decline. [ABSTRACT FROM AUTHOR]

Killer whales (Orcinus orca) are sighted regularly in coastal Alaska during the summer, but little is known about their movements through the area during the winter when weather and light limit the use of boat-based surveys. Acoustic monitoring provides a practical alternative because each extended resident killer whale family group or pod has a unique dialect that can be discerned by differences in their repertoires of stereotyped calls. The repertoires of resident killer whale pods in the northern Gulf of Alaska were updated from earlier studies, and the results used to determine the identity of pods that were recorded on remote hydrophones in Resurrection Bay, Alaska, in the fall, winter, and spring of 1999 to 2004. In total, seven pods of resident killer whales were identified acoustically, comprising four related pods from AB clan and three from AD clan. The frequencies of occurrence of the clans differed between the November to March recording period when AB clan occupied the area, and the April-May period when AD clan was predominant. The sequential use of this habitat during periods of relative prey scarcity has the effect of limiting intergroup resource competition and is consistent with earlier findings that demonstrated divergent resource specialization by sympatric killer whale populations. [ABSTRACT FROM AUTHOR]

The behavioral and predatory patterns of Gulf of Alaska (GOA) transient killer whales ( Orcinus orca) were studied between 2000 and 2005 using remote video and vessel-based observations near the Chiswell Island Steller sea lion ( Eumetopias jubatus) rookery and in the broader Kenai Fjords (KF) region of the northern GOA. GOA transient killer whales were observed on 118 d over the 6-yr period; the median group size was two (range: 1–9). Nine predation events were observed from vessels and an additional sixteen were inferred from remote video studies; all involved Steller sea lions. Estimates from field observations suggest that fifty-nine sea lions were consumed over the summer seasons of 2002–2005; whereas estimates based on published caloric requirements of transient killer whales would suggest a loss of 103 sea lions over the same time period. GOA transients spent a large proportion (43%) of their time resting which may be a strategy for conserving energy. Predation on sea lion pups at the Chiswell Island rookery was greatest during years when a single killer whale was foraging alone and when a 1.5-yr-old calf was evidently being trained to handle prey. Predation on pups was low during years when killer whales were foraging in groups and were observed and presumed to be taking mostly juvenile sea lions. Our study suggests that GOA transients are having a minor effect on the recovery of Steller sea lions in the GOA. [ABSTRACT FROM AUTHOR]

Killer whale ( Orcinus orca Linnaeus, 1758) abundance in the North Pacific is known only for a few populations for which extensive longitudinal data are available, with little quantitative data from more remote regions. Line-transect ship surveys were conducted in July and August of 2001–2003 in coastal waters of the western Gulf of Alaska and the Aleutian Islands. Conventional and Multiple Covariate Distance Sampling methods were used to estimate the abundance of different killer whale ecotypes, which were distinguished based upon morphological and genetic data. Abundance was calculated separately for two data sets that differed in the method by which killer whale group size data were obtained. Initial group size (IGS) data corresponded to estimates of group size at the time of first sighting, and post-encounter group size (PEGS) corresponded to estimates made after closely approaching sighted groups. ‘Resident’-type (fish-eating) killer whales were more abundant than the ‘transient’-type (mammal-eating). Abundance estimates of resident killer whales (991 [95% CI = 379–2,585] [IGS] and 1,587 [95% CI = 608–4,140] [PEGS]), were at least four times greater than those of the transient killer whales (200 [95% CI = 81–488] [IGS] and 251 [95% CI = 97–644] whales [PEGS]). The IGS estimate of abundance is preferred for resident killer whales because the estimate based on PEGS data may show an upward bias. The PEGS estimate of abundance is likely more accurate for transients. Residents were most abundant near Kodiak Island in the northern Gulf of Alaska, around Umnak and Unalaska Islands in the eastern Aleutians, and in Seguam Pass in the central Aleutians. This ecotype was not observed between 156 and 164°W, south of the Alaska Peninsula. In contrast, transient killer whale sightings were found at higher densities south of the Alaska Peninsula between the Shumagin Islands and the eastern Aleutians. Only two sightings of ‘offshore’-type killer whales were recorded during the surveys, one northeast of Unalaska Island and the other south of Kodiak Island. These are the first estimates of abundance of killer whale ecotypes in the Aleutian Islands and Alaska Peninsula area and provide a baseline for quantifying the role of these top predators in their ecosystem. [ABSTRACT FROM AUTHOR]

The article discusses the behavior of harbor seals in the presence of predator transient killer whales. The study was conducted to assess the diving behavior by monitoring harbor seals in the Glacier Bay National Park(GBNP), Alaska. The monitoring of the harbor seal with a VHF headmount transmitter and a timedepth recorder (TDR) for evaluating dive behavior, habitat use and prey selection during and after an encounter is mentioned. A brief history on predators of harbor seals in GBNP is presented. The article also outlines the studies of real-time tracking that provide more useful research of the at-sea behavior of marine mammals.

The article examines the stomach contents collected from a dead adult male killer whale that was found on April 19, 2003 in southwest Prince William Sound in Alaska. Genetic analysis conformed that this was a killer whale from the AT1 population. The whale was moderately decomposed and the cause of death could not be determined. Results of the analysis on the rinsed contents of the stomach indicate that this killer whale fed on sea otters and birds. The minimum number of animals determined from prey items found from in stomach contents included nine harbor seals, five sea otters, one river otter, one cormorant, one sea duck and one octopus.

Killer whales, Orcinus orca (L., 1758), in the North Pacific are classified as three genetically distinct ecotypes: residents (fish-eaters), transients (mammal-eaters), and offshores (probable fish-eaters). Within the transient ecotype, three putative subpopulations have been identified by genetic analysis: West Coast transients, Gulf of Alaska transients, and AT1 transients. Here, we examine the behavior and vocalizations of the AT1 transients, which are found only in the Prince William Sound/Kenai Fjords region, to determine if their acoustic behavior distinguishes them from other genetically distinct transient subpopulations. We identified 14 discrete, pulsed calls in the vocal repertoire of the AT1 transients. These calls were entirely different than those of West Coast and sympatric Gulf of Alaska transients. Despite their large call repertoire, AT1 transients were silent most of the time, utilizing a foraging strategy of stealth, acoustic crypsis, and passive listening for locating marine-mammal prey. Unlike resident killer whales, AT1 transient vocalization types were context specific. For example, lone AT1 transients produced long-distance, high-amplitude pulsed calls in stereotyped sequences to locate other AT1 whales. In contrast, hunting individuals emitted low-amplitude pulsed calls to maintain contact with group members. The repertoire and call-usage patterns of the AT1 transients are consistent with genetic evidence that they are a unique, reproductively and socially isolated subpopulation in danger of extinction. [ABSTRACT FROM AUTHOR]

Killer whale predation on belugas in Cook Inlet, Alaska, has become a concern since the decline of these belugas was documented during the 1990s. Accordingly, killer whale sightings were compiled from systematic surveys, observer databases, and anecdotal accounts. Killer whales have been relatively common in lower Cook Inlet (at least 100 sightings from 1975 to 2002), but in the upper Inlet, north of Kalgin Island, sightings were infrequent (18 in 27 yr), especially prior to the 1990s. Beach cast beluga carcasses with teeth marks and missing flesh also provided evidence of killer whale predation. Most observed killer whale/beluga interactions were in the upper Inlet. During 11 of 15 observed interactions, belugas were obviously injured or killed, either through direct attacks or indirectly as a result of stranding. Assuming at least one beluga mortality occurred during the other four encounters, we can account for 21 belugas killed between 1985 and 2002. This would suggest a minimum estimate of roughly 1/yr and does not include at least three instances where beluga calves accompanied an adult that was attacked. [ABSTRACT FROM AUTHOR]

Uses thirteen years of encounter data (1984?1996) to examine killer whale distribution within Prince William Sound, Alaska. Patterns of area use which comprised differences between resident pods and transient groups and differences among resident groups; Finding that resident pods frequented large open passages, while transient groups used the narrow passages and bays in the southwest, which likely reflects resident use of salmon and transient use of pinniped prey resources, as well as the different foraging strategies required for these prey types; Decline in the use of the Sound by the AT1 transient whales; Finding that nearshore foraging for pinniped prey by the AT1 transient whales was more common in areas where these whales spend a disproportionate amount of time, suggesting that these areas were critical foraging habitat for them and that no similar pattern emerged for Open-water Foraging for cetaceans by AT1 whales, nor for foraging by the resident whales.

Presents a study that documented the traditional ecological knowledge of the Alaska Native hunters of beluga whales in Cook Inlet to add information available on the population. Importance of summer feeding to Cook Inlet belugas; Predation by killer whales; Information on beluga cows and calves.

Presents research which studied declining sea otter populations in western Alaska. Increased killer whale predation; Resulting sea urchin density and deforestation of kelp beds; Effects of anthropogenic changes in the offshore oceanic ecosystem.

We observed a white adult male killer whale (Orcinus orca) on 7 August 2000 off the north side of Adak Island, Aleutians. An open saddle and a rounded dorsal fin tip suggest that this whale belongs to the fish-eating ("resident") ecotype. A circular scar matching a cookie-cutter shark (Isistius sp.) bite mark suggested that the animal originated in warmer waters. Photographs and description provided here should enable individual identification should this animal be seen again. [ABSTRACT FROM AUTHOR]

Details the first record of an anomalously white killer whale, Orcinus orca, near St. Lawrence Island, Northern Bering Sea, Alaska. Reason for the rareness of sighting an adult white male whale; Description of the whale; Types of whales; Factor associated with partial or complete albinism.

Reports that ecologists have discovered that the sea otter population around the Alaskan coastline has declined dramatically in the late 1990s. Estimations that the otter population has dropped 90 percent in the 1990s; How ecologists have witnessed sea otters being eaten by orcas; The puzzling nature of this find since the usual diet of orcas do not include otter; Implications of the declining otter population.

The article outlines the study conducted by Craig Matkin and colleagues, marine biologists of the North Gulf Oceanic Society on the negative impact of crude oil spill at Prince William Sound in Alaska. In 2006, Exxon Valdez spilled 42 million liters of crude oil in the area and the effects are still reverberating among the local killer whales. They found that such incident brought negative impact to the whale populace because during the first year after the spill, approximately 14 of 36 whales died and its birthrate plummeted. The also found that the whales that surfaced in the oil suffered irreparable damage to their lungs.