The Hectorâ€™s Dolphin Endangered Animal Report 2010
Introduction Name: Hector’s dolphin
Museum in Wellington, Te Papa. He examined the
Scientific Name: Cephalorhynchus Hectori
first specimen found of the dolphin. The species was
Habitat: Coastal Waters
scientifically described by Belgian zoologist Pierre
Location: North And South Island
Joseph van Beneden in 1881.
Population: Approximately 7270
Primarily grey, black and white with a distinctive stripe running across its belly, this cetacean, air breathing,
Hector’s dolphins are the world’s smallest and rarest
water living mammal, is most recognizable by its lack
dolphins which are only found in New Zealand. The
of discernible beak and its round dorsal fin.
Hector’s dolphin is the smallest in the delphinidae family as well as the rarest oceanic species. Hector’s dolphin was named after Sir James Hector (1834 – 1907). He was the curator of the Colonial
The dolphin is classified as a vulnerable threatened species in the most recent IUCN, World Conservation Union, listings of globally threatened animal species.
‘Over the last thirty years New Zealand has lost on average 570 endangered Hector’s dolphins a year, that’s over 5,000 deaths each decade.’ WWF, 2010
Hector’s dolphin’s distribution 1/3 offshore distribution protected (Population continues to decline) Unprotected areas (Population continues to decline)
The problem Unprotected distribution Hector’s dolphins are endemic to the coastal
and in deeper water in winter, presumably in
regions of New Zealand and they have a patchy
response to movements of their prey species.
distribution around the entire South Island. The
The main populations are found between Motunau
species has a preference for shallow, coastal
and Timaru on the East Coast of the South Island,
waters less than 100m deep. This means they are
on the West Coast of the South Island, and in
most commonly seen close to shore, although
Foveaux Strait Te Waewae Bay area in Southland.
in shallow regions they have been sighted up to
Currently they are trapped accidentally in trawls
34km from the coast.
and gill nets. Some parts of their habitat have
In some areas, there is a pronounced seasonal
been protected, but to save this declining species,
difference in distribution, with dolphins being sighted further offshore
more areas around New Zealand will have to be declared no-go zones for coastal gill nets.
Population of Hector’s dolphin
Decrease of population from 1970–2010
Population decrease Scientists estimate that more than 26,000 Hector’s
dolphin species. The Cetacean Specialist Group of
dolphins lived around New Zealand’s shores in the
the Species Survival Commission of IUCN, the world
1970s. Today, it is thought that just 7270 remain
scientific experts on cetacean conservation, have
which is less than one third of the 1970s’ population.
assessed Hector’s dolphin as a threatened species
The Hector’s dolphin was given ‘threatened species’
of vulnerable status using the agreed threatened
status by the Department of Conservation in
species criteria. Research shows that even if all
available actions were implemented today, by 2055
Today, Hector’s dolphins are listed on the World Conservation Union’s Red List as endangered, and are among the most rare of the world’s 32 marine
the population would still be smaller than it was in 1970. The most likely outcome is that they will continue to decline, just at a slower rate than before.
‘Such very small population of Hector’s dolphins have a high extinction risk simply due to stochastic factors. Marine and Freshwater research, 2010
Number of dolphins
Hector’s dolphin’s mortality (1969–2009)
Mortality Mortality of Hector’s dolphin in gill-net fisheries is a
that was created in 1988, which reduces the amount
threat to local populations throughout its range. This
of gill net fishing. Conservation measures are most
population viability analysis extends previous work by
urgently needed for the highly threatened North Island
exploring a wider range of fishing levels and population
population, in particular the dolphins at the northern
growth rates, by incorporating year to year and
and southern end of this range.
environmental variability and by reporting results for
Reducing fisheries mortality to levels approaching zero
smaller population units.
shows the strongest promise of meeting national and
Ten of the 16 populations are likely to continue to
international guidelines for managing dolphin bycatch,
decline, five are indefinite, and one is likely to increase.
with a 59% probability of reaching 50% of estimated
All populations subjected to high fishing effort are
1970 population size by 2050.
declining. The only population predicted to increase is partly protected by a marine mammal sanctuary
Atlantic spotted Dolphin
Shorter length, shorter life Hector’s Dolphins are one of the smallest dolphins in the world. As adults the Hector’s
species. By contrast, larger dolphins such as the bottlenose live to between 25 and 50 years.
Dolphin has a length of 1.5 meters and weigh
A dolphin’s age is estimated from the layers in a
in at only 50 kilograms.
cross section of tooth. Because of their small size,
Hector’s dolphins do not live as long as others, the smaller the species, the shorter the lifespan. Out of more than 80 Hector’s which have been dissected some of them caught in fishing nets, the oldest recorded ages have been 19 years for a female and 20 for a male. Some individuals may live longer than this, but the ages are comparable to those recorded for other Cephalorhynchus
they do not have enough reserves to make long journeys through fish starved oceans, to either populate other coasts or to mix with other of their kind. The lungs of a Hector’s dolphin are about the size of a human’s, and when trapped in one, it takes about the same length of time for them to drown as it would a person.
Number of dolphins
‘New zealand Hector’s dolphin populations are more susceptible to extinction than other species.’ Zoology and wildlife conservation, 1998
Hour glass Dolphin
Atlantic Spotted Dolphin
Population of different breeds
Life expectancy of endangered species Life expectancy Number of reproductions
4–8 yrs Humpback Whale
3–4 yrs Hooker’s Sea Lion
The causes Breeding ovulation The slow rate of Hector’s dolphin’s reproduction
dolphins are having a very difficult time replacing
makes their populations vulnerable. Females aren’t
members of their population as fast as they are
sexually mature until they are between seven
and nine years old, that would be equivalent to a
The gestation period for Hector’s Dolphin is believed
human not being able to reproduce until they are
to be about a year. Calves are born in spring and early
about 30 years old.
summer, November to February. The calf starts eating
They produce just one calf every two to four years.
solid food at about 6 months of age, but stays with its
One female might only produce four calves in her
mother for a full year. Minimum calving intervals range
20 year lifetime and this is just enough to replace
from 2 – 4 years, but the mother does not conceive
the number of dolphins that die naturally. Hector’s
again until the calf is independent.
Breeding ovulation Year 3
Calves are old enough to live on their own Nov
Year 2 Calves are born Nov
Jan Year 1
‘Fishing nets continue to kill Hector’s dolphins faster than they can breed.’ Global Voice for Wildlife, 2009
73% Set net
Population declining threats Dolphins and people have shared our shores and
boats. Newborn dolphins are particularly
bays for centuries. In recent years, there has been a
vulnerable as they swim relatively slowly, close to
worldwide increase in awareness of marine mammals
the surface. Some have been killed by boat
and a greater desire to protect them.
propellers, when unwary boats have run them over.
Set net fishing poses a major threat to Hector’s
Other potential threats to their survival include
dolphins. Like all marine mammals they need to
trawling, marine pollution, disease and impacts
come to the surface regularly to breathe. If they
of tourism and aquaculture. They are also
become tangled in set nets, they will hold their
harmed by boat strikes, pollution and coastal
breath until they suffocate.
developments which degrade their habitat, and
Because these dolphins swim close to the shores and harbours, they are at risk of being injured by
future threats may arise from climate change, overfishing and aquaculture.
Commercial net Recreational net Unknown net
Number of dolphins
Reported net entanglements
Net sets Hector’s dolphins use echo-location to locate their
Set nets are the single most significant threat to
prey. Dolphins send out a stream of high frequency
the survival of Hector’s dolphins as the dolphins
clicking noises and when the sound strikes an object
get entangled in these nets and drown. Without
it bounces back and the dolphin can tell by listening
restrictions placed on commercial fishing, the risk of
what the object is, what kind of fish it is, how far
extinction of Hector’s dolphins would be very high.
away it is and how fast it is moving.
A 2008 report by the National Institute of Water
The dolphins cannot easily detect the nets, even
and Atmospheric Research (NIWA) estimates that
when using echolocation. This enables them to see
110 to 150 Hector’s dolphins die in commercial set
the hard parts of prey, or solid objects like rocks,
nets every year.
but because nets are soft and flexible they do not bounce sounds back to the dolphin.
‘Hector’s dolphin’s population today, is less than one-third of the 1970’s population.’ WWF, 2010
Strategy What needs to be done Specific ways in which protection could be improved
gill net and trawl fisheries continuing, in areas where
includes protection from gill nets and set nets,
Hector’s dolphins are found need to be considered.
allowing the Hector’s dolphins to recover. Better protection of harbours are needed.
We need to have a nationwide ban on gill nets in order to save the dolphins from extinction. This
Extending protection is needed on the west coast
means banning trawl fishing in waters less than 100
South Island to 6 nautical miles offshore, year-round.
meters deep in areas where Hector’s dolphins are
Also extending protection at Banks Peninsula area
found. Full protection is needed for dolphins across
offshore to 15 nautical miles as Hector’s dolphins
their entire range and for areas where they historically
are found well beyond the 4 nautical mile protection
ranged in the past.
boundary in this relatively shallow area. Increased protection from trawl fisheries and observers on all
‘The only population predicted to increase is partly protected by a marine mammal sanctuary which reduces the amount of gill net fishing.’ WWF, 2010
What has already been done On 15 November 2007, the World Wide Fund for
mammals illegal. Under this act, the Department of
Nature launched an online petition asking Helen
Conservation designated the Banks Peninsula Marine
Clark, New Zealand’s Prime Minister at the time,
Mammal Sanctuary in 1988, effectively prohibiting
to introduce emergency measures to protect the
commercial gillnetting and restricting recreational
Hector’s dolphins. New measures were introduced
by the Ministry of Fisheries in 2008 effectively banning gill netting within 4 of the majority of the South Island’s east and south coasts, regulating gill netting on the South Island’s west coast out to 3.7km offshore and extending the gillnet ban on the North Island’s west coast to 13 km offshore. There are also restrictions on trawling in some of these areas. The New Zealand Marine Mammals Protection Act has made the deliberate killing or injury of marine
These were surpassed by new Ministry of Fisheries regulations in 2008 which ban gillnetting to four nautical miles off the majority of the South Island’s east and south coasts, regulate gillnetting on the South Island’s west coast to two nautical miles (3.7 kilometres) offshore. Five marine mammal sanctuaries were designated around the coastline in 2008 to provide additional protection from non fisheries related impacts
â€˜Total protection is the only way to give the dolphins the chance to recover so they are no longer at risk of extinction.â€™ Forest and Bird, 2010
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