Natural Entrapments of Killer Whales (Orcinus orca): A Review of Cases and Assessment of Intervention Techniques

Identifying mortality sources and mitigation solutions is crucial in species management and conservation. In killer whales (Orcinus orca), mortality events may pose a serious concern for the conservation of small discrete populations, especially if they involve entire groups. This study investigated 19 incidents involving 116 killer whales from a minimum of five populations becoming naturally entrapped in inshore areas of the North Pacific (n = 12) and North Atlantic (n = 7) oceans between 1949 and 2019. Here, we aim to provide an assessment of possible causal factors, lethality and human responses to these events. Site characteristics and group size identified three categories of entrapments. In Category 1, nine cases involved small groups of killer whales (median = 5, range: 1–9) at sites characterized by severe geographic and food constraints. Four cases in Category 2 included larger groups (median= 14, range: 6–19) and entrapment sites with no obvious geographic constraints but at which man-made structures could have acted as deterrents. Five cases assigned to Category 3 involved lone, often young individuals settling in a restricted home range and engaging in interactions with people and boats. Overall, all or some of the killer whales swam out on their own after a mean of 36 d of entrapment (range: 1–172, SD = 51, n = 9 cases), died of nutritional/physiological stress after 58 d (range: 42–90, SD = 21, n = 3 cases) or of injury after ~5 years of daily interactions with boat traffic (n = 1 case). Indication of the killer whales' declining condition or being at risk of injury, and of poor habitat quality, led to the decision to intervene in seven cases where a variety of methods were used to guide or relocate remaining individuals back to open waters after 39 d (SD = 51, range = 8–150). Monitoring protocols, which aided in identifying entrapment situations, and intervention methods which enhanced the health and survival of entrapped killer whales, are discussed.

Download Full-text

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

Canadian Journal of Zoology ◽

10.1139/z89-365 ◽

1989 ◽

Vol 67 (10) ◽

pp. 2592-2595 ◽

Cited By ~ 21

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.

Download Full-text

Killer Whales (Orcinus orca) Off the North Carolina Coast 1709–2011

Journal of North Carolina Academy of Science ◽

10.7572/2167-5880-128.2.39 ◽

2012 ◽

Vol 128 (2) ◽

pp. 39-43

Author(s):

John Hairr

Keyword(s):

North Carolina ◽

Killer Whale ◽

Popular Literature ◽

Historical Record ◽

Orcinus Orca ◽

Killer Whales ◽

The West ◽

Outer Banks ◽

The North ◽

North Carolina Coast

Abstract Killer whales, Orcinus orca, were first reported off North Carolina by naturalist John Lawson in 1709, and during the 20th century were documented from North Carolina eight times in the scientific and popular literature. The most recent confirmed sighting of killer whales off North Carolina was in the spring of 2011. There have been no reports of killer whale deaths from North Carolina. There has been only one killer whale stranded along the North Carolina coast, with the animal being alive when it was returned to the sea. All sightings have been in the waters of the Atlantic Ocean, none on the west side of the Outer Banks in the waters of Pamlico or Currituck sounds. Only three confirmed reports are from nearshore waters, while the rest were spotted more than 20 km offshore. Orcas are most frequently reported from the waters off the Outer Banks from Cape Lookout north to the Virginia border. A 200 yr gap exists in the historical record of killer whales from North Carolina.

Download Full-text

Interaction between killer whales ( Orcinus orca) and a leatherback turtle ( Dermochelys coriacea) off the north-eastern coast of Venezuela

Marine Biodiversity Records ◽

10.1017/s1755267209000669 ◽

2009 ◽

Vol 2 ◽

Cited By ~ 1

Author(s):

Lenin Oviedo ◽

María Alejandra Esteves ◽

Estefanía Alfe ◽

Romina Acevedo ◽

Jaime Bolaños-Jiménez

Keyword(s):

Orcinus Orca ◽

Dermochelys Coriacea ◽

Eastern Coast ◽

Killer Whales ◽

Leatherback Turtle ◽

The North ◽

North Eastern

Download Full-text

Ultrasonic whistles of killer whales (Orcinus orca) recorded in the North Pacific (L)

The Journal of the Acoustical Society of America ◽

10.1121/1.4764874 ◽

2012 ◽

Vol 132 (6) ◽

pp. 3618-3621 ◽

Cited By ~ 15

Author(s):

Olga A. Filatova ◽

John K. B. Ford ◽

Craig O. Matkin ◽

Lance G. Barrett-Lennard ◽

Alexander M. Burdin ◽

...

Keyword(s):

North Pacific ◽

Orcinus Orca ◽

Killer Whales ◽

The North ◽

The North Pacific

Download Full-text

High-frequency modulated signals of killer whales (Orcinus orca) in the North Pacific

The Journal of the Acoustical Society of America ◽

10.1121/1.3654283 ◽

2011 ◽

Vol 130 (4) ◽

pp. 2322-2322

Author(s):

Anne E. Simonis ◽

Simone Baumann-Pickering ◽

Erin Oleson ◽

Mariana L. Melcón ◽

Martin Gassmann ◽

...

Keyword(s):

North Pacific ◽

High Frequency ◽

Orcinus Orca ◽

Killer Whales ◽

The North ◽

Modulated Signals ◽

The North Pacific

Download Full-text

High-frequency modulated signals of killer whales (Orcinus orca) in the North Pacific

The Journal of the Acoustical Society of America ◽

10.1121/1.3690963 ◽

2012 ◽

Vol 131 (4) ◽

pp. EL295-EL301 ◽

Cited By ~ 19

Author(s):

Anne E. Simonis ◽

Simone Baumann-Pickering ◽

Erin Oleson ◽

Mariana L. Melcón ◽

Martin Gassmann ◽

...

Keyword(s):

North Pacific ◽

High Frequency ◽

Orcinus Orca ◽

Killer Whales ◽

The North ◽

Modulated Signals ◽

The North Pacific

Download Full-text

Passive acoustic monitoring of killer whales (Orcinus orca) reveals year-round distribution and residency patterns in the Gulf of Alaska

Scientific Reports ◽

10.1038/s41598-021-99668-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Hannah J. Myers ◽

Daniel W. Olsen ◽

Craig O. Matkin ◽

Lara A. Horstmann ◽

Brenda Konar

Keyword(s):

Killer Whale ◽

Marine Ecosystem ◽

Distribution Patterns ◽

Gulf Of Alaska ◽

Acoustic Monitoring ◽

Orcinus Orca ◽

Killer Whales ◽

Passive Acoustic Monitoring ◽

The North ◽

Passive Acoustic

AbstractKiller 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.

Download Full-text

Historic and current distribution patterns, and minimum abundance of killer whales (Orcinus orca) in the north-west Atlantic

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315413001409 ◽

2013 ◽

Vol 94 (6) ◽

pp. 1253-1265 ◽

Cited By ~ 7

Author(s):

Jack W. Lawson ◽

Tara S. Stevens

Keyword(s):

Distribution Patterns ◽

Orcinus Orca ◽

Killer Whales ◽

North West ◽

The North ◽

North Eastern ◽

Comprehensive Examination ◽

Coastal Shelf ◽

Eastern Usa ◽

Image Collection

This study represents the first comprehensive examination of the distribution and abundance of killer whales (Orcinus orca) in the north-west Atlantic. Based on a collation of sightings data and a multi-year photographic catalogue of killer whales, 836 sighting events have been recorded between 1758 and 2012, with most occurring in the last ten years. Killer whales were most commonly observed during June–September in Newfoundland/Labrador, Canada. Most sightings were made close to shore, although many occurred beyond coastal shelf areas and in water depths in excess of 3000 m. Relatively fewer sightings were recorded on the Scotian Shelf, in the Gulf of St Lawrence or the north-eastern USA, despite appreciable aerial and vessel-based cetacean survey effort. In the north-west Atlantic, killer whales have been sighted both alone and in groups, with group sizes ranging from 2 to 30 whales (rarely more than 15, although an aggregation of 100 was reported 43 years ago). Groups usually comprised 2–6 individuals. Based on photographic records, there are at least 67 identified killer whales in the northwest Atlantic; this is an underestimate, since a large portion of our image collection was not of sufficient quality to be considered in the analysis, and many of the whales do not have easily discernible markings. The discovery curve of newly-identified whales has not plateaued, suggesting that there are more whales to identify. These data allow us to better understand the ecology of these killer whales, and provide a baseline against which population changes and distribution patterns can be assessed.

Download Full-text