2. Above: The impressive sub-adult male Augie (WA03) with 3-year-old sister Elle (WA11) (Image: MIRG)
Ningaloo – Winter Program 2015
The Ningaloo Coast in the NW of Western Australia is the only known tropical low-latitude location in the
world where killer whales (Orcinus orca) can be regularly observed and studied on a long term basis.
The most regular visiting killer whale (kw) family off the Ningaloo coast, locally known as the ‘gang of
four’, set a record for activity during the winter months of 2015 with 33 reported sightings, 23 verified
with photo ID. During this period, this group, led by matriarch Hook (WA2) with her offspring Augie (WA3)
Spinner (WA10) and the younger Elle (WA11), were responsible for 11 successful and two unsuccessful
humpback whale calf (Megaptera novaeangliae) predation events confirmed with photo ID. These all
occurred over a three month period from late June to late September. We were on site for ten of these
events spending a total of 36.5hrs on focal follows recording foraging/feeding behaviour and
documenting eight of the 11 confirmed predations and the two unsuccessful attempts.
Of the 23 sightings confirmed with photo ID, just 10 animals of the 30 catalogued were sighted during the
winter season. The majority of these sightings (n.20) were attributed to the gang of four (Hook, Augie,
Spinner and the young calf Elle). On two occasions the socialites Jigsaw and Pimp (WA4 and WA5) teamed
up with Hook’s group, an association noticed several times in previous years. The one remaining sighting
was of another known family, consisting of Willo, Wisp and Pec with her two-year old calf Fin (WA6, WA7,
WA8 & WA20) seen down towards Coral Bay on the 1st June. This family were not sighted again for the
duration of the winter. All 13 humpback calf predation events witnessed involved Hook’s family of four,
with one of these (14 July) also including Jigsaw & Pimp.
The increased presence of the ‘gang of four’ allowed us to observe and document predator prey
interactions for extended periods and increase our understanding of killer whale foraging strategies and
the defensive responses of the humpbacks cows and male escorts. As observed in other years these
predation events attracted large numbers of sharks (predominately whalers) – often exceeding 30 in
number. A satellite tag was successfully deployed on 30 June (Hook WA02) though a suspected technical
problem prevented transmissions after just 3 days. A further three biopsy samples were collected (Hook
WA2, Spinner WA10 & Elle WA11) bringing the total sampled from the mammal feeding winter group up
to 12.
3. Ningaloo - Summer Program - New Year Orcas at the Cape
Three re-sightings of orcas visiting the Ningaloo coast in summer were reported in 2016. On January 1
a pod of 12 were observed foraging off Hunters beach, then almost 12 months later, on Dec 11, four
animals from this group, including a prominent male, were seen off Tantabiddi. The first sighting of this
family was of two individuals photographed off Tantabiddi in February 2015 by E.Mcdonald and
V.Brosig with Brad Webster on Venture IV, who reported several other animals off at a distance to the
west. The third was a lone male sighted off the pier on Jan 6, 2016 – first photographed back in Jan 2010
off Tantabiddi.
Male orca in pod of 12, NW Cape 01/01/2016 (Image: Ben Gryta)
To date, the few summer sightings over the past 10 years have not included any of the familiar
mammal eating winter animals. These recent repeat summer sightings could indicate these animals are
part of two separate groups, each with distinctive seasonal distribution and prey preference. Samples of
the prey bits collected will give some insight into the diet of these animals frequenting the Ningaloo coast
in summer.
Male & female orca in pod of 4, Off Tantabiddi 11/12/2016 (Image: Axel Passeck)
Ningaloo - Winter 2016 - new calf joins winter kw group
Killer whale sightings reported during the winter months of 2016 fell to 20, with 12 confirmed by photo ID.
Six humpback calf predations were reported, three in southern sector of our study area, closer to Coral Bay.
In contrast to the winter of 2015, the 2016 winter season saw 19 animals identified including 17 known
individuals and an unknown female with a new calf. The low number of sightings may have been due to the
record numbers of humpback calves recorded along the Ningaloo coast during July and August, giving the kw
groups increased access to prey and reducing the amount of hunting forays required up and down the reef
front. In early August a further two killer whales (kws) were identified and successfully biopsied.
WA16 with new female (WA24) and new calf (WA25) 12/08/2016 (Image: J Marx)
4. How much of a calf is consumed at predation events varies greatly. We have documented feeding lasting only
a few minutes, eating just the tongue and tissue around the jaw and throat pleats, to lasting over two hours
where a large part of the animal is consumed. During this time the killer whales share the prize among the
group, a pod member, often the matriarch, patrols the perimeter keeping the sharks at bay. When the killer
whales, the main predator, take their preferred parts, the sharks get their turn. After that the carcasses settle
on the reef providing a rich source of nutrients for other scavengers and reef dwellers.
New season calf (WA25) part of the kw group preying on humpback calves (Image J.Marx)
The killer whale population in the Ningaloo area is increasing in number with several new adults and a few
calves joining the winter humpback hunters over the past several years. Ongoing monitoring will be required
to assess the top-down influence this group of apex predators has on the marine ecosystem in the Ningaloo
region. Further publications assessing this overall effect of killer whale predation on the WA humpback
population, detailing insights into the killer whales hunting strategies and feeding behaviour, and the
humpbacks defensive manoeuvres during predation events, are in preparation.
Estimate of annual calf kills
Assessing the energy needs of these animals is crucial to determining the overall impact (real and potential)
on the WA group IV humpback population. To date, our records of temporal and spatial foraging behaviour –
including kill frequency data from 72 hrs of focal follows applied to the 24 animals from the four known
family groups – suggests the total take of calves is approx 400 during each season (June to October). Further
study of the killer whales (kws) population growth and diet in this region is required for a longer-term
assessment of the impact this may have on the humpback population. An example of their proficiency and at
times extreme feeding capacity became evident from an event in mid July 2015 when the regular ‘gang of
four’ attacked four calves over a period of seven hours resulting in three successful kills.
5. Giant squid tail fin remains (left) and beaks above - collected March 2016
Adult kw with large squid in tow - her calf in close, feeding Partly eaten giant squid – Architeuthis dux
South Coast Program – Summer 2016
In contrast to the Ningaloo, the deeper canyon waters off WA’s south coast is one of the few places in the
world where off-shore killer whales can be regularly found and studied. The summer and autumn of 2016 off
the Bremer coast saw large aggregations of several cetacean species. We conducted two research trips during
this period spending a total of 36 days in the area. Many of the regular 30-40 killer whales were sighted daily
with others passing through occasionally. On six occasions large tight groups of up to 40 sperm whale
(Physeter macrocephalus) were sighted, predominately cows, juveniles and calves, with a few large bulls
lurking on the perimeter. On one of these days, a few sperm whales were involved in a surface interaction
with a killer whale group when approximately 30 sperm whales surfaced all around them – the killer whales
quickly moved on. On several days large groups (n. 50-100) of long finned pilot whales (Globicephala melas)
cruised through this 8-10 km feeding zone uninterested in or deterred from the prey that were keeping the
killer whales occupied. False killer whales (Pseudorca crassidens) were also sighted on four occasions (groups
of 15-30) sometimes in a broad formation and traversing the area with 40-50 offshore bottlenose dolphins
(Tursiops truncates). Mega pods of common dolphins (Delphinus delphis) close to 1000 in number were also
observed travelling through the canyon slopes at speed. Samples from several squid species were collected
including the giant Architeuthus sp. These large squid, and probably other smaller squid species are among
the target prey items for the predators in these deeper offshore waters.
Along with the large scale movements of this southern killer whale population, investigation of their diet is a
main focus of our research attention. The various groups found here have a varied selection of prey
available. These include squid, pelagic fishes (kingfish, tuna, mahi mahi, sunfish & sharks) and on occasion
small or juvenile whales. To determine whether all groups (matrilines) share a general diet or if prey
preference differs between the killer whale groups here is a high research priority. Work programmes this
southern summer (2017) are concentrating on methods to further investigate the whales’ target species.
6. Biopsy dart showing blubber at tip
Lucy SC09 (satellite tagged in 2014) seen here in pursuit of a beaked whale in 2015. (Image R. Wellard )
Several new killer whale individuals were recorded by photo ID last summer. There are a few largely
resident groups regularly found here each year, as well as several more transient groups including some
seen in different years and others recorded just once. Tissue samples (skin & blubber) were successfully
collected (by biopsy) from 18 animals bringing the total sampled from these southern groups to 29. More
samples are required for analysis of group kinship, though analysis is now underway for genetic
comparisons between the larger groups of killer whales found around Australia. On a larger scale,
samples from this population and samples from the tropical NW region have been included in a study
into killer whale genomic diversity worldwide – a collaboration led by Andy Foote of NHM Denmark and
Phillip Morin of the Marine Mammal Division SWFSC NOAA.
Lucy’s pod – a taste for whale
Another item on the kws menu (albeit rarely observed) is the unfortunate beaked whale (Mesoplodon sp.)
that on occasion is preyed upon while traversing through the area. The inclusion of a marine mammal on the
diet adds a level of complexity to the whole feeding dynamic in this relatively small highly active feeding
zone. With few smaller whales available in this area, it appears the animals responsible for the beaked whale
predation may have a more varied diet than mammal eating killer whales studied in other locations. A
detailed account of these beaked whale events in this area was recently published (Wellard et al).
7. Exmouth Gulf – humpback nursery
A rare sight: 3 humpback cows with calf - seldom share the same patch. The tursiops feed among the mobile FADs.
Humpbacks continue the surge – Ningaloo Coast; a major calving area
After the apparent low numbers witnessed in 2014, the WA group IV humpback migration off the
Ningaloo coast started strongly in early June 2016, gaining momentum right through into August. Whales
were still sighted travelling north in late August when the first animals heading back south were rounding
the NW cape.
From the arrival of the first humpback calves in late June and early July, we recorded both calf numbers
and the proportion of cow calf pairs with escorts. Previous data we published in 2014 (Pitman et al.)
documenting killer whale predation of humpback calves along the Ningaloo coast suggested that
humpback calves are a predictable, plentiful and readily taken prey source for killer whales and
scavenging sharks off the Ningaloo coast for about 4 months during winter. Our recent observations of
cow calf pods made as part of monitoring during the humpback’s northern migration (62 hours over 14
days during July & August 2016) suggest that as many as 450 calves are born west and south of NW Cape
between late June and mid August. This is a conservative estimate as it is based on data collected within
just two km west of the reef and not including calves born in the area after mid August. Calves born in the
Ningaloo area could therefore represent as much as 20% of the annual WA total, given the humpback
population of approx 24,000 with an annual increase estimate of 8-10%.
The proportion of cow calf pairs with escort was 45%, consistent with previous years. The killer whale
predation success rate is halved when escorts are present. How many cow calf pods make the Exmouth
Gulf their nursery or travel further north and east is still unclear. The gulf waters have proved to be a safe
haven from predation with all of the 54 recorded attacks over last eight years, occurring west or north of
the NW Cape – from Coral Bay to the Muiron Islands. Of these recorded attacks 35 (65%) were successful.
Many questions remain:
Why don't the predators venture into the gulf – is the humpback acoustic barrage a barrier ? Why
are we not getting more reports of killer whale activity further to the NE ? – The Karratha and
Kimberley coasts also have good numbers of humpback calves.
Where do these predators go and what to they feed on when the humpbacks are gone during
summer ? The presence of smaller numbers of ‘other’ killer whales off the Ningaloo coast during
summer, not seen with the winter mammal eating groups, suggests there’s a third WA group.
What is the new carrying capacity / stable population size for the WA group IV humpbacks ? What
influence will the presence of a recovered killer whale population have in maintaining a balance ?
8. A sub-adult female from Lucy Pod - Bremer sub-basin region – sampled on 01042016 (Image: R.Pitman)
Humpback cow, with cookiecutter shark bite – Exmouth Gulf (Inset: Biopsy dart with tissue sample)
Genetic analysis – Killer whales
Australian killer whale genetic diversity will be analysed at the Molecular Ecology Lab,
Flinders University S.A. using biopsy tissue samples collected from the northwest (tropical Ningaloo), the
temperate southwest (Bremer sub-basin) and samples from several strandings on the east coast and
Tasmania. To date, with many thousands of photo ID images there is no evidence of mating or
associations between the animals from these areas. Also, while there is some minor
variation in the general appearance, the main characteristics for Type are similar across Australia
(exception of rare visits from Type B and Type C). When compared with other known ecotypes from
the southern hemisphere the animals found regularly off WA mostly resemble the Antarctic Type A,
though are generally not known to grow as large. All samples will also be used to assist in the study of
killer whale diet through fatty acid and stable isotope analysis.
Genetic analysis – Humpback whales
A total of 135 humpback whale tissue samples have now been collected over the last three seasons off the
Ningaloo coast and in the Exmouth Gulf area. A broad range of animal’s age and sex was selected to gain
understanding of the genetic diversity within the breeding stock D (WA group IV) population. Part of this
selection included cow, calf and escort (trio) pods to further investigate the motive behind the escort’s
defence of calves when under attack from killer whales. Though likely to be mating related behaviour, we will
analyse for kinship within these groups. The sample size of 135 animals consists of 49 cows, 21 calves, 42
escorts and 23 adults of unknown sex or association. Within these there are 21 trios where the cow, calf and
escort were all sampled. A sample of cows, from cow calf pairs, will be tested for pregnancy to help
understand the population growth of humpback whales. With lower numbers in past decades, a healthier
population due to increased availability of food per individual, could at least in part lead to a decreased
calving interval, in turn helping to explain the rapid recovery of this population.
