scholarly journals Disentangling Natural and Anthropogenic Forms of Mortality and Serious Injury in a Poorly Studied Pelagic Dolphin

2021 ◽  
Vol 8 ◽  
Author(s):  
Erin Ashe ◽  
Rob Williams ◽  
Alexandra Morton ◽  
Philip S. Hammond
Keyword(s):  
Killer Whale ◽  
Anthropogenic Impacts ◽  
Predatory Behavior ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Mammal Conservation ◽  
White Side ◽  
Fishery Interactions ◽  
Serious Injury

Killer whale (Orcinus orca) populations specialize in both prey and prey acquisition tactics around the world and may be a primary evolutionary driver of the habits of small cetaceans. Entanglement in fishing gear is the most significant anthropogenic threat to the survival of cetaceans worldwide. Distinguishing between natural and human-caused sources of mortality and injury is a key task in marine mammal conservation and management. In British Columbia (BC), Canada, mammal-eating killer whales co-occur with Pacific white-sided dolphins (Lagenorhynchus obliquidens). Bycatch mortality rates are unknown here due to lack of systematic fisheries observer coverage. Drawing from more than three decades of first-hand observations of killer whale attacks on Pacific white-sided dolphins, we identify common themes with respect to predatory behavior of killer whales and anti-predatory responses of dolphins. With input from veterinary pathologists, we outline clues to distinguish killer whale rake marks from scars and wounds likely to be caused by fishery interactions. We examined photographs of 415 well-marked Pacific white-side dolphins for evidence of injuries and scars consistent with either killer whale attacks or fishery interactions. In this case study, healed scars from interactions with killer whale predators were ∼8× more common than scars from fishery interactions (3.9 vs. 0.5%), suggesting that predation is a much bigger threat to Pacific white-sided dolphins in the study area than anthropogenic impacts, or that dolphins are much less likely to survive a fishery interaction than a predation attempt. To advance our knowledge on poorly studied species, multiple lines of evidence will be needed.

scholarly journals Family feud: permanent group splitting in a highly philopatric mammal, the killer whale (Orcinus orca)

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Eva H. Stredulinsky ◽  
Chris T. Darimont ◽  
Lance Barrett-Lennard ◽  
Graeme M. Ellis ◽  
John K. B. Ford
Keyword(s):  
Killer Whale ◽  
Group Structure ◽  
Group Living ◽  
Orcinus Orca ◽  
Learning Approaches ◽  
Killer Whales ◽  
Internal Factors ◽  
Individual Fitness ◽  
Leadership Experience

Abstract For animals that tend to remain with their natal group rather than individually disperse, group sizes may become too large to benefit individual fitness. In such cases, group splitting (or fission) allows philopatric animals to form more optimal group sizes without sacrificing all familiar social relationships. Although permanent group splitting is observed in many mammals, it occurs relatively infrequently. Here, we use combined generalized modeling and machine learning approaches to provide a comprehensive examination of group splitting in a population of killer whales (Orcinus orca) that occurred over three decades. Fission occurred both along and across maternal lines, where animals dispersed in parallel with their closest maternal kin. Group splitting was more common: (1) in larger natal groups, (2) when the common maternal ancestor was no longer alive, and (3) among groups with greater substructuring. The death of a matriarch did not appear to immediately trigger splitting. Our data suggest intragroup competition for food, leadership experience and kinship are important factors that influence group splitting in this population. Our approach provides a foundation for future studies to examine the dynamics and consequences of matrilineal fission in killer whales and other taxa. Significance statement Group living among mammals often involves long-term social affiliation, strengthened by kinship and cooperative behaviours. As such, changes in group membership may have significant consequences for individuals’ fitness and a population’s genetic structure. Permanent group splitting is a complex and relatively rare phenomenon that has yet to be examined in detail in killer whales. In the context of a growing population, in which offspring of both sexes remain with their mothers for life, we provide the first in-depth examination of group splitting in killer whales, where splitting occurs both along and across maternal lines. We also undertake the first comprehensive assessment of how killer whale intragroup cohesion is influenced by both external and internal factors, including group structure, population and group demography, and resource abundance.

Development of intentional stranding hunting techniques in killer whale (Orcinus orca) calves at Crozet Archipelago

1995 ◽  
Vol 73 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Christophe Guinet ◽  
Jérome Bouvier
Keyword(s):  
Growth Curve ◽  
Parental Investment ◽  
Killer Whale ◽  
Elephant Seal ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Juvenile Female ◽  
Adult Females ◽  
Social Transfer ◽  
High Degree

This paper describes the trend in the practice of what we interpret to be the "intentional stranding" hunting technique of two juvenile female killer whales (Orcinus orca), A4 and A5, belonging to pod A on the beaches of Possession Island, Crozet Archipelago. Pod A was composed of three adult females, A2, A3, A6, and one adult male, A1. A2 is A4's mother and A3 is A5's mother. The year of birth and thus the probable age of the two juveniles were estimated from their growth curve determined by means of a photogrammetric technique. These observations indicate that at Crozet Archipelago, juvenile killer whales first practiced intentional stranding on their own when they were 4–5 years old. Their first attempt to capture elephant seal pups by means of this technique was observed when they were 5–6 years old. However, 5- to 6-year-old juveniles still needed the assistance of an adult female to return to the water with their prey. This study indicates that learning hunting techniques needs a high degree of skill and requires high parental investment to reduce the associated risk. Furthermore, social transfer, through apprenticeship, is probably one of the mechanisms that enables the high degree of adaptability observed in killer whales.

scholarly journals Middle/late Miocene hoplocetine sperm whale remains (Odontoceti: Physeteridae) of North Germany with an emended classification of the Hoplocetinae

Fossil Record ◽  
2006 ◽  
Vol 9 (1) ◽  
pp. 61-86 ◽  
Author(s):  
O. Hampe
Keyword(s):  
Late Miocene ◽  
Killer Whale ◽  
Sperm Whale ◽  
Tooth Wear ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Functional Tooth ◽  
North Germany ◽  
Middle Pliocene

Abstract. Hoplocetus ritzi n. sp. is a new hoplocetine physeterid from the Bolboforma fragori /subfragoris Zone of the middle/late Miocene mica-clay of Groß Pampau in Schleswig-Holstein, North Germany. The Hoplocetinae are known from the early Miocene to the Pliocene. Comparative studies of cranial characters and tooth morphology allow an emended diagnosis of the Hoplocetinae Cabrera, 1926. Four genera, Diaphorocetus, Idiorophus, Scaldicetus, and Hoplocetus are included in this subfamily. The pattern of functional tooth wear deduced from the described Hoplocetus ritzi n. sp. remains is reminescent of that known from Orcinus orca. The hoplocetine physeterids possibly occupied the killer whale niche before the killer whales appeared during the middle Pliocene. Mit Hoplocetusritzi n. sp. wird ein neuer hoplocetiner Physeteride beschrieben. Der Fund stammt aus der Bolboformafragori /subfragoris Zone des mittel-/obermiozänen Glimmertons von Groß Pampau in Schleswig-Holstein, Norddeutschland. Die Hoplocetinae sind vom unteren Miozän bis ins Pliozän nachgewiesen. Anhand vergleichender Untersuchungen an wenigen Schädelmerkmalen und der Zahnmorphologie gelingt eine Neudiagnose der Hoplocetinae Cabrera, 1926 und eine vorläufige Abgrenzung zwischen den als valid angesehenen Gattungen dieser Unterfamilie, Diaphorocetus, Idiorophus, Scaldicetus und Hoplocetus. Das Abkauungsmuster der Zähne von Hoplocetusritzi n. sp. erinnert an das des heutigen Orcinusorca. Möglicherweise sind die hoplocetinen Pottwale habituell den Schwertwalen, die erdgeschichtlich erstmals im mittleren Pliozän auftreten, vergleichbar. doi:10.1002/mmng.200600002

Preliminary findings of restriction fragment differences in mitochondrial DNA among killer whales (Orcinus orca)

1989 ◽  
Vol 67 (10) ◽  
pp. 2592-2595 ◽  
Author(s):  
Tracy A. Stevens ◽  
Deborah A. Duffield ◽  
Edward D. Asper ◽  
K. Gilbey Hewlett ◽  
Al Bolz ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
North Atlantic ◽  
North Pacific ◽  
Killer Whale ◽  
Vancouver Island ◽  
Restriction Pattern ◽  
Orcinus Orca ◽  
Killer Whales ◽  
The North ◽  
The North Pacific

A preliminary assessment of mitochondrial DNA restriction patterns in the killer whale (Orcinus orca) was conducted using 10 captive North Atlantic killer whales from the southeastern coast of Iceland, a captive-born offspring of one of these whales, and 9 North Pacific killer whales. No restriction pattern variation was seen among these whales, using the enzymes BamH I, Bgl II, Hinf I, Kpn I, or Pvu II. Restriction pattern variation was found using the enzyme Hae III. This restriction endonuclease distinguished the North Atlantic killer whales (type 1) from the North Pacific killer whales. The North Pacific killer whales were further differentiated into two groups: those originating from the "resident" communities of the Vancouver Island region (type 2), and those from the "transient" community of Vancouver Island, as well as those stranded along the Oregon coast (type 3). The observed Hae III restriction pattern differences suggest that mitochondrial DNA analysis will be a valuable technique for investigating regional and local distributions of maternal lineages among killer whale pods, especially in the North Pacific.

Herring schooling manoeuvres in response to killer whale attacks

1999 ◽  
Vol 77 (10) ◽  
pp. 1540-1546 ◽  
Author(s):  
Leif Nøttestad ◽  
Bjørn Erik Axelsen
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Killer Whale ◽  
Clupea Harengus ◽  
Orcinus Orca ◽  
Antipredator Behaviour ◽  
Killer Whales ◽  
Predator Prey ◽  
Antipredator Responses ◽  
Different Types

The antipredator behaviour of overwintering Norwegian spring-spawning herring (Clupea harengus L.) was investigated during repeated attacks by killer whales (Orcinus orca L.) in Tysfjord in northwestern Norway. The observations were made using a high-resolution (455 kHz) multibeam sonar. Ten different types of predator-prey interactions were recorded during 54 observed events (an average of one antipredator event every 3.9 min). Antipredator responses included "split," "hourglass," "vacuole," "bend," "dive," "herd," and "fountain." Large attacked schools demonstrated a different repertoire of antipredator manoeuvres than small ones and were less likely to be attacked. Despite being located in the vicinity of the whales, herring schools with a cross section exceeding 460 m2 were not attacked by killer whales. Attacked schools were significantly more circular (p < 0.0001) and had higher relative densities (p < 0.05) than schools that were not attacked.

A comparison of pigmentation features among North Atlantic killer whale (Orcinus orca) populations

2014 ◽  
Vol 94 (6) ◽  
pp. 1335-1341 ◽  
Author(s):  
Pirjo Mäkeläinen ◽  
Ruth Esteban ◽  
Andrew D. Foote ◽  
Sanna Kuningas ◽  
Julius Nielsen ◽  
...  
Keyword(s):  
North Atlantic ◽  
Common Ancestor ◽  
Killer Whale ◽  
Orcinus Orca ◽  
Recent Common Ancestor ◽  
Killer Whales ◽  
Parallel Orientation ◽  
Local Populations ◽  
Most Recent Common Ancestor ◽  
Phylogenetic Divergence

Here we present a comparison of saddle and eye patch patterns of killer whales from Norwegian, Icelandic, British, Spanish and Greenlandic waters. We found only a small amount of variation in saddle patch shapes, which may reflect a recent phylogenetic divergence from the most recent common ancestor. Eye patch shapes were more variable than saddle patches in small details. Most individuals had eye patches with parallel orientation, with the exception of a small group of killer whales from the Hebrides, which, as previously reported, had sloping eye patches that sloped downward at the posterior end. This differentiation in pigmentation patterns of the Hebridean killer whales from neighbouring populations could reflect one or more of several evolutionary processes, including a deeper phylogenetic divergence, low gene flow with other local populations and drift.

scholarly journals Predicting global killer whale population collapse from PCB pollution

Science ◽  
2018 ◽  
Vol 361 (6409) ◽  
pp. 1373-1376 ◽  
Author(s):  
Jean-Pierre Desforges ◽  
Ailsa Hall ◽  
Bernie McConnell ◽  
Aqqalu Rosing-Asvid ◽  
Jonathan L. Barber ◽  
...  
Keyword(s):  
Polychlorinated Biphenyl ◽  
Killer Whale ◽  
Trophic Levels ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Model Framework ◽  
Population Collapse ◽  
Mediated Effects ◽  
Chemical Class

Killer whales (Orcinus orca) are among the most highly polychlorinated biphenyl (PCB)–contaminated mammals in the world, raising concern about the health consequences of current PCB exposures. Using an individual-based model framework and globally available data on PCB concentrations in killer whale tissues, we show that PCB-mediated effects on reproduction and immune function threaten the long-term viability of >50% of the world’s killer whale populations. PCB-mediated effects over the coming 100 years predicted that killer whale populations near industrialized regions, and those feeding at high trophic levels regardless of location, are at high risk of population collapse. Despite a near-global ban of PCBs more than 30 years ago, the world’s killer whales illustrate the troubling persistence of this chemical class.

scholarly journals Behavioural Changes in Belugas (Delphinapterus leucas) During a Killer Whale (Orcinus orca) Attack in Southwest Hudson Bay

2017 ◽  
Vol 130 (4) ◽  
pp. 315 ◽  
Author(s):  
Kristin H Westdal ◽  
Jeremy Davies ◽  
Andy McPherson ◽  
Jack Orr ◽  
Steven H Ferguson
Keyword(s):  
Killer Whale ◽  
High Tide ◽  
Arctic Sea Ice ◽  
Survival Strategies ◽  
Orcinus Orca ◽  
Delphinapterus Leucas ◽  
Hudson Bay ◽  
Stock Management ◽  
Killer Whales ◽  
Risk Of Predation

Killer Whales (Orcinus orca) were observed on 4 August 2012 attacking Belugas (Delphinapterus leucas) at high tide near the mouth of the Seal River (59°9'19"N, 94°45'28"W) in southwest Hudson Bay, near the location where six Belugas had been fitted with satellite transmitters three weeks earlier. The distribution of Belugas was analyzed before, during, and after the attack. In the presence of Killer Whales, the six Belugas altered their behaviour by reducing their combined range size from 285 km2 four days before the attack to 172 km2 on the day of the attack. Their range more than tripled, to 655 km2, in the days immediately following the attack before returning to the pre-attack size. Following the attack, the tagged Belugas expanded their range northward, going from a mean pre-attack distance of 9.4 km from the attack site to a maximum of 23.5 km. Visual observations of Belugas clumping together and moving toward shore corroborated satellite data. This evasive behaviour by Belugas was different from that reported for Narwhals (Monodon monoceros) suggesting that the two monodontid species may have evolved different survival strategies related to the risk of Killer Whale predation. With predicted changes to Arctic sea ice, the summeringhabitat of Belugas will be available to their main predator for longer periods. A better understanding of Beluga behaviour and risk of predation is required for Beluga conservation and stock management.

Killer whale harrassment of Adélie penguins at Ross Island

2005 ◽  
Vol 17 (3) ◽  
pp. 385-386 ◽  
Author(s):  
GRANT BALLARD ◽  
DAVID G. AINLEY
Keyword(s):  
Killer Whale ◽  
The Other ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Pygoscelis Adeliae ◽  
Emperor Penguins ◽  
Other Hand ◽  
Close Proximity ◽  
Aptenodytes Forsteri ◽  
Adélie Penguins

On innumerable occasions, Adélie (Pygoscelis adeliae) and emperor penguins (Aptenodytes forsteri) have been observed in close proximity to killer whales (Orcinus orca), with no whale-penguin interactions reported. On the other hand, killer whales reportedly harass and eat seabirds on occasion (Walker 1968: p. 1122, Stacey et al. 1990, Williams et al. 1990). Killer whales are known to prey on young king penguins (A. patagonica) as they are fledging (Guinet 1992, Guinet & Bouvier 1995) and occasionally take emperor penguins (Mikhalev et al. 1981). Thomas et al. (1981) report killer whales chasing Adélies. Here we report the only observations of Adélie-killer whale interactions observed in nine field seasons on Ross Island.

scholarly journals Amino acid δ15N differences consistent with killer whale ecotypes in the Arctic and Northwest Atlantic

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249641
Author(s):  
Cory J. D. Matthews ◽  
Jack W. Lawson ◽  
Steven H. Ferguson
Keyword(s):  
Killer Whale ◽  
Isotope Analysis ◽  
Canadian Arctic ◽  
Tooth Wear ◽  
Orcinus Orca ◽  
The Arctic ◽  
Killer Whales ◽  
Northwest Atlantic ◽  
Ecological Adaptations ◽  
Bimodal Variation

Ecotypes are groups within a species with different ecological adaptations than their conspecifics. Eastern North Pacific (ENP) killer whale (Orcinus orca) ecotypes differ in their diet, behavior, and morphology, but the same is not known for this species in the eastern Canadian Arctic (ECA) and Northwest Atlantic (NWA). Using compound-specific stable isotope analysis (CSIA) of amino acids (AAs), we compared δ15N patterns of the primary trophic and source AA pair, glutamic acid/glutamine (Glx) and phenylalanine (Phe), in dentine collagen of (1) sympatric ENP killer whale ecotypes with well-characterized diet differences and (2) ECA/NWA killer whales with unknown diets. δ15NGlx-Phe was significantly higher in the ENP fish-eating (FE) than mammal-eating (ME) ecotype (19.2 ± 0.4‰ vs. 13.5 ± 0.7‰, respectively). Similar bimodal variation in δ15NGlx-Phe indicated analogous dietary divisions among ECA/NWA killer whales, with two killer whales having higher δ15NGlx-Phe (16.5 ± 0.0‰) than the others (13.5 ± 0.6‰). Inferences of dietary divisions between these killer whales were supported by parallel differences in threonine δ15N (–33.5 ± 1.6‰ and –40.4 ± 1.1‰, respectively), given the negative correlation between δ15NThr and TP across a range of marine consumers. CSIA-AA results for ECA/NWA whales, coupled with differences in tooth wear (a correlate for diet), are consistent with ecotype characteristics reported in ENP and other killer whale populations, thus adding to documented ecological divergence in this species worldwide.

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