Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters

1998 ◽  
Vol 76 (8) ◽  
pp. 1456-1471 ◽  
Author(s):  
John KB Ford ◽  
Graeme M Ellis ◽  
Lance G Barrett-Lennard ◽  
Alexandra B Morton ◽  
Rod S Palm ◽  
...  
Keyword(s):  
British Columbia ◽  
Chinook Salmon ◽  
Stomach Contents ◽  
Orcinus Orca ◽  
Foraging Strategies ◽  
Field Observations ◽  
Killer Whales ◽  
Sympatric Populations ◽  
Mammal Species ◽  
Dietary Specialization

Two forms of killer whale (Orcinus orca), resident and transient, occur sympatrically in coastal waters of British Columbia, Washington State, and southeastern Alaska. The two forms do not mix, and differ in seasonal distribution, social structure, and behaviour. These distinctions have been attributed to apparent differences in diet, although no comprehensive comparative analysis of the diets of the two forms had been undertaken. Here we present such an analysis, based on field observations of predation and on the stomach contents of stranded killer whales collected over a 20-year period. In total, 22 species of fish and 1 species of squid were documented in the diet of resident-type killer whales; 12 of these are previously unrecorded as prey of O. orca. Despite the diversity of fish species taken, resident whales have a clear preference for salmon prey. In field observations of feeding, 96% of fish taken were salmonids. Six species of salmonids were identified from prey fragments, with chinook salmon (Oncorhynchus tshawytscha) being the most common. The stomach contents of stranded residents also indicated a preference for chinook salmon. On rare occasions, resident whales were seen to harass marine mammals, but no kills were confirmed and no mammalian remains were found in the stomachs of stranded residents. Transient killer whales were observed to prey only on pinnipeds, cetaceans, and seabirds. Six mammal species were taken, with over half of observed attacks involving harbour seals (Phoca vitulina). Seabirds do not appear to represent a significant prey resource. This study thus reveals the existence of strikingly divergent prey preferences of resident and transient killer whales, which are reflected in distinctive foraging strategies and related sociobiological traits of these sympatric populations.

Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters

1998 ◽  
Vol 76 (8) ◽  
pp. 1456-1471 ◽  
Author(s):  
John K.B. Ford ◽  
Graeme M. Ellis ◽  
Lance G. Barrett-Lennard ◽  
Alexandra B. Morton ◽  
Rod S. Palm ◽  
...  
Keyword(s):  
British Columbia ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Sympatric Populations ◽  
Dietary Specialization ◽  
Coastal British Columbia

Seasonal movements and foraging behaviour of northern resident killer whales (Orcinus orca) in relation to the inshore distribution of salmon (Oncorhynchus spp.) in British Columbia

1996 ◽  
Vol 74 (6) ◽  
pp. 983-991 ◽  
Author(s):  
Linda M. Nichol ◽  
David M. Shackleton
Keyword(s):  
British Columbia ◽  
Chinook Salmon ◽  
Chum Salmon ◽  
Foraging Behaviour ◽  
Pink Salmon ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Arrival Times ◽  
True Preference ◽  
Strong Current

The hypothesis that northern resident killer whales (Orcinus orca) move in response to the seasonal availability of salmon (Oncorhynchus spp.) was tested using sightings and acoustic recordings of whales and data on the timing and abundance of salmon in Johnstone Strait, off Vancouver Island, between 1984 and 1988, and from King Island, on the central British Columbia coast, for a 2-month period in 1989. Whales were most abundant in Johnstone Strait between July and October when salmon migrate through the strait. Individual whales seen in the strait during summer were observed around King Island in spring 1989, coinciding with local sockeye and chinook salmon runs. In Johnstone Strait during summer 1988, whales foraged along the shore and in areas of strong current, where salmon occur in high densities. However, less than half of the 16 pods in the northern resident community were present on more than 15% of summer days (1984–1988). The occurrence of 6 pods (A1, A4, A5, C1, D1, and H1) in Johnstone Strait during summer was positively and significantly associated with sockeye and pink salmon abundance, whereas pod G1 was positively and significantly associated with chum salmon. Although we demonstrate an association between certain pods and certain salmon species, we cannot determine whether this reflects the true preference of pods or represents differences in the whales' arrival times in Johnstone Strait that are related to other factors. Our data suggest that within the northern resident community, pods may have seasonal ranges.

Fireproof killer whales (Orcinus orca): flame-retardant chemicals and the conservation imperative in the charismatic icon of British Columbia, Canada

2006 ◽  
Vol 63 (1) ◽  
pp. 224-234 ◽  
Author(s):  
Peter S Ross
Keyword(s):  
British Columbia ◽  
Trophic Level ◽  
Polybrominated Diphenyl Ethers ◽  
Marine Mammals ◽  
Polychlorinated Biphenyl ◽  
High Trophic Level ◽  
Orcinus Orca ◽  
Weight Of Evidence ◽  
Older Individuals ◽  
Killer Whales

Long-lived and high trophic level marine mammals are vulnerable to accumulating often very high concentrations of persistent chemicals, including pesticides, industrial by-products, and flame retardants. In the case of killer whales (Orcinus orca), some of the older individuals currently frequenting the coastal waters of British Columbia (BC) were born during the First World War, well before the advent of widespread chemical manufacture and use. BC's killer whales are now among the most polychlorinated biphenyl (PCB) contaminated marine mammals in the world. While the "legacy" PCBs have largely been banned, polybrominated diphenyl ethers (PBDEs) have recently emerged as a major concern. The endocrine-disrupting nature of these two persistent fire retardants in biota spells trouble at the top of the food chain, with increasing evidence of effects on reproductive health, the immune system, and development in exposed mammals. The heavy contamination of BC's killer whales, coupled with their long life span and high trophic level, highlights the need for a "weight of evidence" approach in research, conservation planning, and regulatory decisions. Given the global nature of contaminant dispersion, such approaches can only be effective when carried out on both national and international scales.

Acoustic behaviour of resident killer whales (Orcinus orca) off Vancouver Island, British Columbia

1989 ◽  
Vol 67 (3) ◽  
pp. 727-745 ◽  
Author(s):  
John K. B. Ford
Keyword(s):  
British Columbia ◽  
Emotional State ◽  
Vancouver Island ◽  
Orcinus Orca ◽  
Social Signals ◽  
Killer Whales ◽  
Acoustic Behaviour ◽  
Call Type ◽  
Discrete Calls ◽  
And Function

Recordings of underwater vocalizations and behavioural observations were collected from 16 photographically identified resident pods of killer whales (Orcinus orca) off Vancouver Island, British Columbia, during 1978–1983. Vocalizations recorded during 43 days spent with three representative pods were analyzed for each of five activity states: foraging, travelling, group-resting, socializing, and beach-rubbing. The whales produced three types of sounds that were assumed to be social signals: discrete calls, variable calls, and aberrant calls. Discrete calls dominated vocalization in most contexts. An increase in production of variable and aberrant calls was observed during socializing and beach-rubbing activities. Each resident pod had a group-specific repertoire of 7–17 discrete call types (mean = 10.7) that was consistent over a number of years. The relative use of different calls varied with activity, but no call type was correlated exclusively with any behaviour or circumstance that could be identified. Discrete calls probably function as intragroup contact signals to maintain pod cohesion and coordinate activities. Structural modulations of standard call formats and variations in frequencies of call use appear to carry information on the emotional state of vocalizing individuals. Group-specific repertoires of calls may increase the effectiveness and reliability of this contact system and function as indicators of pod affiliation.

scholarly journals Southern resident killer whales encounter higher prey densities than northern resident killer whales during summer

2021 ◽  
pp. 1-12
Author(s):  
Mei Sato ◽  
Andrew W. Trites ◽  
Stéphane Gauthier
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Killer Whale ◽  
Orcinus Orca ◽  
Foraging Success ◽  
Killer Whales ◽  
Juan De Fuca ◽  
Abundance And Distribution ◽  
Juan De Fuca Strait ◽  
Growing Population

The decline of southern resident killer whales (Orcinus orca) may be due to a shortage of prey, but there is little data to test this hypothesis. We compared the availability of prey (Chinook salmon, Oncorhynchus tshawytscha) sought by southern residents in Juan de Fuca Strait during summer with the abundance and distribution of Chinook available to the much larger and growing population of northern resident killer whales feeding in Johnstone Strait. We used ship-based multifrequency echosounders to identify differences in prey fields that may explain the dynamics of these two killer whale populations. Contrary to expectations, we found that both killer whale habitats had patchy distributions of prey that did not differ in their frequencies of occurrence, nor in the size compositions of individual fish. However, the density of fish within each patch was 4–6 times higher in the southern resident killer whale habitat. These findings do not support the hypothesis that southern resident killer whales are experiencing a prey shortage in the Salish Sea during summer and suggest a combination of other factors is affecting overall foraging success.

Live-Capture Killer Whale (Orcinus orca) Fishery, British Columbia and Washington, 1962–73

1975 ◽  
Vol 32 (7) ◽  
pp. 1213-1221 ◽  
Author(s):  
Michael A. Bigg ◽  
Allen A. Wolman
Keyword(s):  
British Columbia ◽  
Body Length ◽  
Killer Whale ◽  
Orcinus Orca ◽  
Killer Whales ◽  
In Captivity

In British Columbia and Washington 263 killer whales (Orcinus orca) were caught during 1962–73 of which 50 were kept for oceanaria, 12 died during capture operations, and the remainder escaped or were released. Peak cropping years were 1967–70 when 77% of all whales removed from the water were taken. Lengths of cropped males were 2.49–6.98 m and females, 2.80–6.25 m. Of 28 females taken an estimated 43% were mature and of 30 males, 20% were adult. The equation relating body length in centimeters and weight in kilograms is W = 0.000208 L2.577. Revenue to netters from the sale of 48 killer whales is estimated to be about $1,000,000. Of 48 whales held in captivity 48% were still alive on April 1, 1974. Survival to the end of 2 yr in captivity is 75% in whales thought to be immature and 13% in adults. The history, capture localities and techniques, and management regulations of the killer whale fishery are also described.

Sign in / Sign up

Export Citation Format

Share Document