scholarly journals Behavior of Killer Whales Orcinus orca during Longline Fishery Interactions in the Southeastern Bering Sea and Adjacent Waters

1995 ◽  
Vol 61 (4) ◽  
pp. 584-589 ◽  
Author(s):  
Kazunari Yano ◽  
Marilyn E. Dahlheim
Keyword(s):  
Bering Sea ◽  
Orcinus Orca ◽  
Longline Fishery ◽  
Killer Whales ◽  
Fishery Interactions

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 Depredation by killer whale (Orcinus orca) and false killer whale (Pseudorca crassidens) on the catch of the Uruguayan pelagic longline fishery in Southwestern Atlantic Ocean

2015 ◽  
Vol 72 (5) ◽  
pp. 1653-1666 ◽  
Author(s):  
Cecilia Passadore ◽  
Andrés Domingo ◽  
Eduardo R. Secchi
Keyword(s):  
Atlantic Ocean ◽  
Killer Whale ◽  
Orcinus Orca ◽  
Longline Fishery ◽  
Southwestern Atlantic ◽  
Killer Whales ◽  
Southwestern Atlantic Ocean ◽  
Pelagic Longline Fishery ◽  
Pseudorca Crassidens ◽  
Pelagic Longline

Abstract This study analyses depredation by killer whales (Orcinus orca) and false killer whales (Pseudorca crassidens) on catches of the Uruguayan pelagic longline fishery in the Southwestern Atlantic Ocean between 1998 and 2007. Data were collected by scientific observers from the National Observer Program of the Tuna Fleet operating in the area between 19°–40.5°S and 20°–54°W. Depredation occurred in 67 of the 1029 sets and was restricted to the area from 25°–40.5°S to 27°–53°W, though larger proportions of depredation (DP: percentage of total fish caught damaged by cetaceans) were observed in the Brazil–Malvinas (Falkland) Confluence area (34°–37°S and 51°–53°W) where most of the fishing effort was concentrated. Depredation occurred year-round though intra-annual variability in its intensity was recorded. The overall DP was 0.37% and was slightly higher in autumn. The spatial analysis showed that DP within grids of 1 × 1° was homogeneous and generally <2.5%. Ten out of 57 fish species caught by the fishery were depredated by cetaceans. Swordfish (Xiphias gladius) showed the highest DP per species (1.17%). Using the frequency of resources selectivity index of Ivlev, it was determined that swordfish was selected as a preferred prey in 43.9% of the sets with depredation. Generalized linear models indicated that distance to coast, year, and vessel were significant variables in explaining the number of fish depredated per fishing event. The presence of killer whales in the fishing ground seems not to affect the catch per unit effort by the longline fishery. The losses caused by depredation of cetaceans on the catch are low with probably minor economic effects to the Uruguayan longline fishing industry.

Personality in captive killer whales (Orcinus orca): A rating approach based on the five-factor model.

2019 ◽  
Vol 133 (2) ◽  
pp. 252-261 ◽  
Author(s):  
Yulán Úbeda ◽  
Sara Ortín ◽  
Judy St. Leger ◽  
Miquel Llorente ◽  
Javier Almunia
Keyword(s):  
Factor Model ◽  
Five Factor Model ◽  
Orcinus Orca ◽  
Killer Whales

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.

Sounds associated with foraging and prey capture in individual fish-eating killer whales, Orcinus orca

2019 ◽  
Vol 146 (5) ◽  
pp. 3475-3486 ◽  
Author(s):  
Marla M. Holt ◽  
M. Bradley Hanson ◽  
Candice K. Emmons ◽  
David K. Haas ◽  
Deborah A. Giles ◽  
...  
Keyword(s):  
Prey Capture ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Individual Fish

scholarly journals Evaluating potential infectious disease threats for southern resident killer whales, Orcinus orca: a model for endangered species

2004 ◽  
Vol 117 (3) ◽  
pp. 253-262 ◽  
Author(s):  
Joseph K. Gaydos ◽  
Kenneth C. Balcomb ◽  
Richard W. Osborne ◽  
Leslie Dierauf
Keyword(s):  
Infectious Disease ◽  
Endangered Species ◽  
Orcinus Orca ◽  
Killer Whales
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