A global image-based data repository of killer whale interactions with elasmobranchs.

Killer whales (Orcinus orca) are marine apex predators distributed across the world’s oceans. In the last 40 years, researchers have increasingly differentiated killer whales into ecotypes based on genetics, morphology, behaviour, acoustic repertoire, habitat, and trophic ecology. While killer whale ecotypes in the Northern Hemisphere are well studied, the recognition of distinct killer whale forms in the Southern Hemisphere is mainly limited to Antarctic waters. Although present in less studied regions, such as along the Atacama Desert coast in the Southeast Pacific Ocean, limited information is available regarding their biology or trophic ecology. Herein, multiple lines of evidence are presented for killer whale predation on marine mammals in northern Chile. Using information from systematic boat-based surveys, whale-watching tour surveys, and reports from fishermen/citizen scientists, 19 killer whale sightings are reported along the coast of northern Chile (from the Arica and Parinacota region in the north to the Atacama region in the south). Killer whales were photo-identified as corresponding to the Southern Hemisphere Type A-like ecotype according to their dorsal fin shape and white eye patch. One killer whale pod, which included two males, one female, one juvenile, and one calf, was resighted six times from 2016 to 2021 in northern Chile and was observed hunting South American sea lions (Otaria flavescens), dusky dolphins (Lagenorhynchus obscurus), and long-beaked common dolphins (Delphinus cf. capensis). Killer whales were observed taking advantage of large aggregations of sea lions associated with the offshore purse-seine fishery. Adult killer whales used the hulls of fishing vessels to prevent sea lions from escaping. Photo-identification analysis of a fin whale (Balaenoptera physalus) catalogue from Mejillones Peninsula showed that 2.6% of all identified whales had apparent rake marks from killer whale teeth on their dorsal fins. These data show that Type A-like killer whales in northern Chile prey on several species of marine mammals.

Killer whales (Orcinus orca) are increasing in occurrence and residence time in the eastern Canadian Arctic (ECA) in part due to a decrease in sea ice associated with global climate change. Killer whales prey on bowhead whales (Balaena mysticetus) of the Eastern Canada-West Greenland (EC-WG) population, but their patterns of predation pressure and effect on the EC-WG population’s ability to recover from historical whaling remain unknown. We analyzed photographs of individual bowhead whale flukes from five regions within the EC-WG population’s geographic range (Cumberland Sound, Foxe Basin, Isabella Bay, Repulse Bay and Disko Bay), taken during 1986 and from 2007 to 2012, to estimate the occurrence of rake marks (parallel scars caused by killer whale teeth). Of 598 identified whales, 10.2 % bore rake marks from killer whales. A higher occurrence of rake marks was found in Repulse and Disko Bays, where primarily adult bowhead whales occur seasonally, than in Foxe Basin, where juveniles and females with calves occur. Older bowheads, which have had greater exposure time to killer whales due to their age, had higher occurrences of rake marks than juveniles and calves, which may indicate that younger whales do not survive killer whale attacks. A high proportion of adult females also had rake marks, perhaps due to protecting their calves from killer whale predation. In order to quantify the effect of killer whales on EC-WG population recovery, further research is needed on the relationship between the occurrence of rake marks and bowhead adult, calf, and juvenile mortality in the ECA, as well as more information about Arctic killer whale ecology.

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. 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. 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. 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. 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. Disease has not been ruled out as a significant contributor to the population decline, particularly in the early stages of the decline.

Quantifying the diet composition of apex marine predators such as killer whales (Orcinus orca) is critical to assessing their food web impacts. Yet, with few exceptions, the feeding ecology of these apex predators remains poorly understood. Here, we use our newly validated quantitative fatty acid signature analysis (QFASA) approach on nearly 200 killer whales and over 900 potential prey to model their diets across the 5000 km span of the North Atlantic. Diet estimates show that killer whales mainly consume other whales in the western North Atlantic (Canadian Arctic, Eastern Canada), seals in the mid-North Atlantic (Greenland), and fish in the eastern North Atlantic (Iceland, Faroe Islands, Norway). Nonetheless, diet estimates also varied widely among individuals within most regions. This level of inter-individual feeding variation should be considered for future ecological studies focusing on killer whales in the North Atlantic and other oceans. These estimates reveal remarkable population- and individual-level variation in the trophic ecology of these killer whales, which can help to assess how their predation impacts community and ecosystem dynamics in changing North Atlantic marine ecosystems. This new approach provides researchers with an invaluable tool to study the feeding ecology of oceanic top predators.

A possible predatory interaction between killer whales (Orcinus orca) and hammerhead sharks (Sphyrna sp.) was observed during April 1991 near Punta Cormorant, Galápagos Islands. Three killer whales were observed in close proximity to a freshly dead female hammerhead. One of the killer whales (approximately 6m in length) was observed motionless in a vertical position above the shark carcass and later was seen chasing an approximately 40cm hammerhead, supposedly a pup born prematurely from the dead shark. The sharks are thought to have been scalloped hammerheads (S. lewini).

Bioaccumulation and enantiomeric profiling of organochlorine pesticides and persistent organic pollutants in the killer whale ( Orcinus orca) from British and Irish waters

Getting Wildlife in Perspective – Have We Thought Enough About Their Diseases?

Killer whales at subantarctic Marion Island have been subjected to several scientific studies. In contrast, up until recently, there has been only one record of these animals documented for neighbouring Prince Edward Island. We here report on killer whale observations at Prince Edward Island during March 2012. During 3 days of opportunistic observations at a fur seal colony on the island, killer whales were sighted on six occasions. These probably represented three different pods numbering 11 individuals in total. During all sightings, individuals were seen hunting subantarctic fur seal pups, with four successful predatory events observed.

We examined the incidence of rake mark scars from killer whales Orcinus orca on the flukes of humpback whales Megaptera novaeangliae throughout the North Pacific to assess geo- graphic variation in predation pressure. We used 3650 identification photographs from 16 wintering or feeding areas collected during 1990 to 1993 to determine conservative estimates in the percentage of whales with rake mark scarring. Dramatic differences were seen in the incidence of rake marks among regions, with highest rates on wintering grounds off Mexico (26 vs. 14% at others) and feed- ing areas off California (20 vs. 6% at others), 2 areas between which humpback whales migrate. Although attacks are rarely witnessed, the prevalence of scars demonstrates that a substantial por- tion of animals are attacked, particularly those that migrate between California and Mexico. Our data also suggest that most attacks occur at or near the wintering grounds in the eastern North Pacific. The prevalence of attacks indicates that killer whale predation has the potential to be a major cause of mortality and a driving force in migratory behavior; however, the location of the attacks is inconsis- tent with the hypothesis that animals migrate to tropical waters to avoid predation. Our conclusion is that, at least in recent decades, attacks are made primarily on calves at the wintering grounds; this contradicts the hypothesis that killer whales historically preyed heavily on large whales in high- latitude feeding areas in the North Pacific.

Since the release of the documentary Blackfish in 2013, millions around the world have focused on the plight of the orca, the most profitable and controversial display animal in history. Yet, until now, no historical account has explained how we came to care about killer whales in the first place. Drawing on interviews, official records, private archives, and his own family history, Jason M. Colby tells the exhilarating and often heartbreaking story of how people came to love the ocean's greatest predator. Historically reviled as dangerous pests, killer whales were dying by the hundreds, even thousands, by the 1950s--the victims of whalers, fishermen, and even the US military. In the Pacific Northwest, fishermen shot them, scientists harpooned them, and the Canadian government mounted a machine gun to eliminate them. But that all changed in 1965, when Seattle entrepreneur Ted Griffin became the first person to swim and perform with a captive killer whale. The show proved wildly popular, and he began capturing and selling others, including Sea World's first Shamu. Over the following decade, live display transformed views of Orcinus orca. The public embraced killer whales as charismatic and friendly, while scientists enjoyed their first access to live orcas. In the Pacific Northwest, these captive encounters reshaped regional values and helped drive environmental activism, including Greenpeace's anti-whaling campaigns. Yet even as Northwesterners taught the world to love whales, they came to oppose their captivity and to fight for the freedom of a marine predator that had become a regional icon. This is the definitive history of how the feared and despised "killer" became the beloved "orca"--and what that has meant for our relationship with the ocean and its creatures.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 316:185-199 (2006) - doi:10.3354/meps316185 Selective foraging by fish-eating killer whales Orcinus orca in British Columbia John K. B. Ford*, Graeme M. Ellis Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, British Columbia V9T 6N7, Canada *Email: fordjo@pac.dfo-mpo.gc.ca ABSTRACT: As the apex non-human marine predator, the killer whale Orcinus orca feeds on a wide diversity of marine fauna. Different ecotypic forms of the species, which often exist in sympatry, may have distinct foraging specialisations. One form found in coastal waters of the temperate NE Pacific Ocean, known as the ‘resident’ ecotype, feeds predominantly on salmonid prey. An earlier study that used opportunistic collection of prey remains from kill sites as an indicator of predation rates suggested that resident killer whales may forage selectively for chinook salmon Oncorhynchus tshawytscha, the largest but one of the least abundant Pacific salmon species. Potential biases in the prey fragment sampling technique, however, made the validity of this finding uncertain. We undertook field studies of foraging behaviour of resident killer whales to resolve this uncertainty and to examine potential variation in prey selection by season, geographical area, group membership and prey availability. Foraging by resident killer whales was found to frequently involve sharing by 2 or more whales. Prey fragments left at kill sites resulted mostly from handling and breaking up of prey for sharing, and all species and sizes of salmonids were shared. Resident killer whale groups in all parts of the study area foraged selectively for chinook salmon, probably because of the species’ large size, high lipid content, and year-round availability in the whales’ range. Chum salmon Oncorhynchus keta, the second largest salmonid, were also taken when available, but smaller sockeye O. nerka and pink O. gorbuscha salmon were not significant prey despite far greater seasonal abundance. Strong selectivity for chinook salmon by resident killer whales probably has a significant influence on foraging tactics and seasonal movements, and also may have important implications for the conservation and management of both predator and prey. KEY WORDS: Prey choice · Food sharing · Foraging specialisation · Salmonid predation Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 316. Online publication date: July 03, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.

Persistent Chemicals![Figure][1] Killer whales are still being damaged by PCBs in the environment. CREDIT: PHOTO: AUDUN RIKARDSEN Until they were recognized as highly toxic and carcinogenic, polychlorinated biphenyls (PCBs) were once used widely. Their production was banned in the United States in 1978, though they are still produced globally and persist in the environment. Persistent organic compounds, like PCBs, magnify across trophic levels, and thus apex predators are particularly susceptible to their ill effects. Desforges et al. looked at the continuing impact of PCBs on one of the largest marine predators, the killer whale. Using globally available data, the authors found high concentrations of PCBs within killer whale tissues. These are likely to precipitate declines across killer whale populations, particularly those that feed at high trophic levels and are the closest to industrialized areas. Science , this issue p. [1373][2] [1]: pending:yes [2]: /lookup/doi/10.1126/science.aat1953

Movement, site fidelity and connectivity have important consequences for the evolution of population structure and therefore the conservation and management of a species. In this study photographs of naturally marked killer whales collected from sites across the Northeast Atlantic are used to estimate fidelity to sampling locations and movement between locations, expressed as transition probabilities, pt, using maximum likelihood methods. High transition probabilities suggest there is high inter-annual site fidelity to all locations, and large-scale movement between the spawning and wintering grounds of both Norwegian and Iceland stocks of Atlantic herring. There was no evidence of movement between the Norwegian herring grounds and Icelandic herring grounds, or between the mackerel fishing grounds and the herring fishing grounds. Thus the movement of predictable and abundant prey resources can lead to intrinsic isolation in this species We also find movement between the Northern Isles, Scotland and East Iceland. An association network indicates that killer whales predating seals around the Northern Isles, Scotland are linked to the community of killer whales that follow the Icelandic summer-spawning herring. This adds support to existing evidence of a broad niche width in some populations.

Underwater sounds come with a wide range of frequency components and with a wide range of time intervals. For example, individual killer whale ( Orcinus orca) calls are typically one or two seconds long. Humpback whale (Megaptera novaeangliae) calls range from second long moans to half-hour songs. Speed boats can pass a hydrophone in seconds to minutes. Large ships create signals above background for many minutes. Here fixed 100x100 dimension spectrograms having exponentially increasing time windows of 3, 15, 75, 375, 1875, 9375 seconds are calculated and classified in real time via an autoencoder used as an acoustic pattern detector followed by a supervised convolutional neural network with softmax output. The autoencoder was trained on underwater sound (∼1 Tb) at Orcasound Lab, San Juan Island, WA. The system is designed to classify incoming real-time signals to one or more of twelve different classes (background, killer whale, Southern Resident, Biggs killer whale, humpback whale, breaking waves, kayak paddles, speedboat, displacement boat, large ship, large ship with shaft rub, large ship with repeating sound pattern). The design and efficacy of this detection/classification system will be reported.

Steller sea lions (Eumetopias jubatus) increased in the eastern portion of their range while declining in the Gulf of Alaska and Aleutian Islands from the late 1970s to late 1990s. We constructed ecosystem models of the central and western Aleutians and of southeast Alaska to simultaneously evaluate four hypotheses explaining sea lion dynamics: killer whale (Orcinus orca) predation, ocean productivity, fisheries, and competition with other species. Comparisons of model predictions with historical time series data indicate that all four factors likely contributed to the trends observed in sea lion numbers in both ecosystems. Changes in ocean productivity conveyed by the Pacific Decadal Oscillation influenced the abundance trajectory of several species. Fishing could have affected the ecosystem structure by influencing the abundance of Atka mackerel (Pleurogrammus monopterygius) in the Aleutians and Pacific herring (Clupea pallasii) in southeast Alaska. Pacific halibut (Hippoglossus stenolepis) in the Aleutians and arrowtooth flounder (Atheresthes stomias) in southeast Alaska appear to impede sea lion population growth through competitive interactions. Predation by killer whales was important when sea lions were less abundant in the 1990s in the Aleutians and in the 1960s in Southeast Alaska, but appear to have little effect when sea lion numbers were high.