False Killer Whale Pseudorca crassidens (Owen, 1846)

Zaeschmar, Jochen R.; Estrela, Guilherme

doi:10.1007/978-3-319-65038-8_102-1

Cited by 4 publications

(6 citation statements)

References 122 publications

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“…Due to a lack of skulls with intact teeth, mean interdental distance for false killer whale Pseudorca crassidens was determined from mandibular tooth row length and number of tooth alveoli. Included were two specimens of the Museo de Delfines, Pucusana (Lima), one adult (CEPEC-003) and another subadult (JCR-744), plus an adult skull graphically well-documented in Odell and McClune (1999).…”

Section: Methodsmentioning

confidence: 99%

Antagonistic Behavior by Common Bottlenose Dolphin Tursiops truncatus as Cause of Death for Two Burmeister’s Porpoises Phocoena spinipinnis, in Northern Chile

Guerra-Correa,

Páez-Godoy,

Van Waerebeek

2023

Preprint

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We present the first evidence of lethal interspecific aggressive behavior against Burmeister’s porpoise Phocoena spinipinnis, in a non-predatory context, and the first indications of such behavior in a cetacean from Chilean waters. Two cases, both adult males, are described. Analysis of the fresh tooth rakes, specifically the inter-rake distance, points to common bottlenose dolphin Tursiops truncatus as aggressor. Interdental distances measured on skulls allowed us to exclude Orcinus orca, Globicephala melas, Lagenorhynchus obscurus and Pseudorca crassidens. Evidence of severe blunt trauma, including extensive subdermal hematomas, rupture of pleura and extrusion of lung parenchyma, underscores the level of violent aggression. The reason is unknown but Tursiops truncatus is well-documented to occasionally harass and kill harbour porpoises Phocoena phocoena in the Northern Hemisphere. Considering the scarce information available on the biology and behavioral ecology of Burmeister’s porpoises in Chile and elsewhere, we recommend more systematic field research. Also, as to help formulate effective management measures that can mitigate the main threat for this species in Chile (as in Peru), i.e. fisheries interactions. In Chile, P. spinipinnis is classified as Data Deficient (D.S. N°06-2017), so its real conservation status is unknown.

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Section: Methodsmentioning

confidence: 99%

Antagonistic Behavior by Common Bottlenose Dolphin Tursiops truncatus as Cause of Death for Two Burmeister’s Porpoises Phocoena spinipinnis, in Northern Chile

Guerra-Correa,

Páez-Godoy,

Van Waerebeek

2023

Preprint

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“…In contrast, two other schools of false killer whales were seen to swim though a group of Risso's dolphins and to pass by a group of pilot whales, without causing any apparent disturbance. False killer whales are believed to be predators of spinner dolphins, billfish and other large fish (Norris et al, 1994;Odell and McClune, 1999;Strickland in Kiefner, 2002).…”

Section: False Killer Whale (Pseudorca Crassidens)mentioning

confidence: 99%

Observations of cetaceans in the Maldives, 1990-2002

Anderson¹

2023

JCRM

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Cetaceans observed in Maldivian waters were recorded during the period August 1990 to June 2002, from both vessels-of-opportunity and dedicated cetacean-watching cruises. A total of 1,829 cetacean sightings were recorded during 535 days at sea (equivalent to 261 standardised days). There were 83 multispecies sightings, plus a further 58 sightings without associated effort data and 129 strandings were recorded by the author and others, making a total of 2,108 cetacean records. In all, 20 different species were positively identified from sightings. Spinner dolphins were the most abundant species seen, accounting for 35% of sightings and 53% of numbers. This species showed a clear diurnal pattern of behaviour, with many schools entering the atolls in the early morning, and leaving in the late afternoon. Spinner dolphins regularly occurred with pantropical spotted dolphins and both species associated with yellowfin tuna. Bryde’s whales also associated with yellowfin tuna and appeared to be most common in Maldivian waters during El Niño Southern Oscillation events. Blue whales were only recorded during November to April. Dwarf sperm whales were especially difficult to locate in rough weather but relatively common, making up one sixth of all sightings in flat-calm conditions. Melon-headed whales were particularly common in the south of the Maldives, but rare in the centre and north. Other species recorded were humpback whale, sperm whale, rough-toothed dolphin, Risso’s dolphin, bottlenose dolphin, striped dolphin, Fraser’s dolphin, pygmy killer whale, false killer whale, killer whale, short-finned pilot whale, Blainville’s beaked whale, Longman’s beaked whale and Cuvier’s beaked whale.

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“…Spotted dolphins are commonly found along the southeastern US (Waring et al, 2000). Pygmy killer whales are distributed in tropical and subtropical waters worldwide (Ross and Leatherwood, 1994), overlapping in range with false killer whales, which are distributed in tropical and warm-temperate oceans (Odell and McClune, 1999). Nearly all species observed prior to shock trial tests during site selection and pre-detonation monitoring were also sighted after the tests occurred (see Table 1).…”

Section: Sightingsmentioning

confidence: 99%

Results and evaluation of US Navy shock trial environmental mitigation of marine mammals and sea turtles

Larke¹,

Norman²

2023

JCRM

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A shock trial of a US Navy Destroyer, the USS Winston S. Churchill, was conducted offshore of northern Florida in May and June 2001. The shock trial consisted of three underwater detonation tests, spaced approximately one week apart. Environmental mitigation to minimise the impact of the shock trial on marine mammals and sea turtles was based on a Safety Range of 3.7km (2 n.miles) radius around the detonation site, and a Buffer Zone of an additional 1.85km (1 n.mile) radius beyond the Safety Range. Mitigation included site selection surveys, pre-detonation aerial, vessel and bio-acoustic monitoring, and post-detonation aerial and vessel monitoring. Six species of odontocete and two species of sea turtle were identified during mitigation monitoring, as well as several sightings that could not be identified by species. Site selection aerial surveys were implemented to select a test site with the lowest abundance of marine mammals and sea turtles. Nearly 300 animals were seen during site selection surveys. Pre-detonation aerial and vessel monitoring was implemented to sight any marine mammal and sea turtle within the Safety Range on designated test days, and track the animals until they could be verified to be outside the Safety Range. Approximately 1,200 marine mammals and 32 sea turtles were sighted during pre-detonation monitoring. Pre-detonation bio-acoustic monitoring was implemented to detect large cetaceans within the Safety Range and Buffer Zone; the only calls heard were from dolphins that could not be localised. Post-detonation monitoring was implemented to determine the effectiveness of mitigation procedures. No injured or dead marine mammals or turtles were detected during approximately 185 hours of post-detonation aerial and vessel visual monitoring. Post-detonation monitoring resulted in observations of 767 marine mammals and 42 sea turtles. With only two exceptions, the same marine mammal and sea turtle species were observed prior to, during and after the shock trial test time period. Factors leading to the success of this environmental mitigation effort are summarised, and recommendations for improvements to mitigation efforts of this size and scope are suggested. These recommendations include the use of a simultaneous second aircraft for improved coverage during pre-detonation surveys, increased post-detonation aerial monitoring, equitable survey data for all test sites under consideration during planning stages, and reassessment of bio-acoustic monitoring need and purpose.

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False Killer Whale Pseudorca crassidens (Owen, 1846)

Cited by 4 publications

References 122 publications

Antagonistic Behavior by Common Bottlenose Dolphin Tursiops truncatus as Cause of Death for Two Burmeister’s Porpoises Phocoena spinipinnis, in Northern Chile

Antagonistic Behavior by Common Bottlenose Dolphin Tursiops truncatus as Cause of Death for Two Burmeister’s Porpoises Phocoena spinipinnis, in Northern Chile

Observations of cetaceans in the Maldives, 1990-2002

Results and evaluation of US Navy shock trial environmental mitigation of marine mammals and sea turtles

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