Confirmation of the occurrence of a second killer whale morphotype in South African waters

Best, PB; Meÿer, MA; Kotze, P. G. H.; Seakamela, SM; Hofmeyr, G. J. Greg; Wintner, Sabine P.; Weland, CD; Steinke, Dirk

doi:10.2989/1814232x.2014.923783

Cited by 6 publications

(4 citation statements)

References 22 publications

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“…Together this evidence supports the theory that this flat‐toothed morphotype frequently predates on sharks (Best et al. ).…”

Section: Dietary Specialization and The Concept Of Ecotypessupporting

confidence: 88%

“…Although little is known about the behavior and ecology of killer whales in South African waters, studies have shown the existence of at least two morphotypes, which differ in size and a number of other morphological traits (Best et al. ). Due to limited knowledge on the diet and ecology of these species, they cannot be classified as separate ecotypes (de Bruyn et al.…”

Section: Dietary Specialization and The Concept Of Ecotypesmentioning

confidence: 99%

“…However, the occurrence of this flat‐toothed type appears to be rare in coastal areas (Best et al. ). In deeper shelf waters further offshore, killer whales are known to predate on blue and shortfin mako sharks ( Isurus oxyrinchus ) that have been caught on pelagic longlines (Williams et al.…”

Section: Dietary Specialization and The Concept Of Ecotypesmentioning

confidence: 99%

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Running scared: when predators become prey

2019

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Apex predators play an important role in structuring food webs and are thus key components of healthy, stable ecosystems. While the loss of apex predators has been shown to disrupt ecosystems and trigger trophic cascades, the introduction of novel apex predators to functionally intact systems is less well understood. False Bay, South Africa, is an aggregation site for both white (Carcharodon carcharias) and broadnose sevengill sharks (Notorynchus cepedianus) which together fulfill the role of coastal apex predators. However, since 2009, their position at the top of the food chain has been subverted by the increased presence of killer whales (Orcinus orca) in False Bay. These super predators are known to specialize on certain prey species, and up until 2015 were only documented preying on marine mammals within False Bay. However, in 2015 and 2016 we documented two events in which killer whales preyed upon broadnose sevengill sharks, using a specialized feeding method in which only the liver of each shark was consumed. Although selective feeding on shark liver by killer whales is established, this is the first record of killer whale predations on sevengill sharks in False Bay, and the first documentation of a novel feeding technique, in which killer whales used force applied to the pectoral fins of each shark to rupture the pectoral girdle and thereby access the liver. These predation events resulted in the prolonged absence of sevengill sharks from what is the largest known aggregation site for this species globally, which remained abandoned for up to a month. We briefly review the literature on killer whale behavior, dietary specialization, and population delineation globally and locally, and hypothesize that the novel predations on broadnose sevengill sharks in False Bay are possibly indicative of the arrival of a different sub-group or ecotype of killer whale in the bay, which habitually feeds on sharks. Due to the unique predatory niche occupied by sevengill sharks in False Bay, the increased presence of these particular killer whales in False Bay could have profound impacts throughout the ecosystem.

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“…Together this evidence supports the theory that this flat‐toothed morphotype frequently predates on sharks (Best et al. ).…”

Section: Dietary Specialization and The Concept Of Ecotypessupporting

confidence: 88%

Section: Dietary Specialization and The Concept Of Ecotypesmentioning

confidence: 99%

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Running scared: when predators become prey

2019

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“…Several killer whale populations specialise on a narrow range of prey and can be morphologically and genetically distinct. A rare offshore morphotype of killer whale was described off South Africa by Best et al, (2014). The following year, a distinctive pair of adult males of this morphotype, appeared in the region, and preyed upon various shark species, including white sharks Carcharodon carcharias, extracting and consuming their lipid rich livers (Engelbrecht et al, 2019;Towner et al, 2022a).…”

Section: Lungementioning

confidence: 99%

Novel aerial observations of a group of killer whales Orcinus orca in The Bahamas

Dixon,

Gallagher,

Towner

2023

Front. Mar. Sci.

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Killer Whale Predation on a Giant Manta Ray (Mobula birostris), a Sicklefin Devil Ray (Mobula tarapacana) and a Tiger Shark (Galeocerdo cuvier) in the Southwest Indian Ocean

Terrapon,

Venables,

Lokker

et al. 2024

Afr J Ecol

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Knowledge of killer whale (Orcinus orca) feeding ecology in tropical waters is scarce. In the southwest Indian Ocean, opportunistic sightings provide a valuable source of information to better understand their behaviour, diet and distribution. Here, we compile existing records of killer whale predation on elasmobranchs in the southwest Indian Ocean, including sightings of three undescribed prey species regionally: a giant manta ray (Mobula birostris), a sicklefin devil ray (Mobula tarapacana) and a tiger shark (Galeocerdo cuvier). Documenting such observations is important to increase knowledge on killer whale ecology in the tropics and the cascading impact they might have on prey populations.

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Confirmation of the occurrence of a second killer whale morphotype in South African waters

Abstract: Killer whales

Cited by 6 publications

References 22 publications

Running scared: when predators become prey

Running scared: when predators become prey

Novel aerial observations of a group of killer whales Orcinus orca in The Bahamas

Killer Whale Predation on a Giant Manta Ray (Mobula birostris), a Sicklefin Devil Ray (Mobula tarapacana) and a Tiger Shark (Galeocerdo cuvier) in the Southwest Indian Ocean

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