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DESCRIPTIONEndangered Animal - Hector's Dolphin
The Hectors DolphinEndangered Animal Report 2010
Name: Hectors dolphin
Scientific Name: Cephalorhynchus Hectori
Habitat: Coastal Waters
Location: North And South Island
Population: Approximately 7270
Hectors dolphins are the worlds smallest and rarest
dolphins which are only found in New Zealand. The
Hectors dolphin is the smallest in the delphinidae
family as well as the rarest oceanic species.
Hectors dolphin was named after Sir James Hector
(1834 1907). He was the curator of the Colonial
Museum in Wellington, Te Papa. He examined the
first specimen found of the dolphin. The species was
scientifically described by Belgian zoologist Pierre
Joseph van Beneden in 1881.
Primarily grey, black and white with a distinctive stripe
running across its belly, this cetacean, air breathing,
water living mammal, is most recognizable by its lack
of discernible beak and its round dorsal fin.
The dolphin is classified as a vulnerable threatened
species in the most recent IUCN, World Conservation
Union, listings of globally threatened animal species.
Hectors dolphins are endemic to the coastal
regions of New Zealand and they have a patchy
distribution around the entire South Island. The
species has a preference for shallow, coastal
waters less than 100m deep. This means they are
most commonly seen close to shore, although
in shallow regions they have been sighted up to
34km from the coast.
In some areas, there is a pronounced seasonal
difference in distribution, with dolphins being
sighted further offshore
and in deeper water in winter, presumably in
response to movements of their prey species.
The main populations are found between Motunau
and Timaru on the East Coast of the South Island,
on the West Coast of the South Island, and in
Foveaux Strait Te Waewae Bay area in Southland.
Currently they are trapped accidentally in trawls
and gill nets. Some parts of their habitat have
been protected, but to save this declining species,
more areas around New Zealand will have to be
declared no-go zones for coastal gill nets.
Hectors dolphins distribution
1/3 offshore distribution protected(Population continues to decline)
Unprotected areas(Population continues to decline)
Over the last thirty years New Zealand has lost on average 570 endangered Hectors dolphins a year, thats over 5,000 deaths each decade.
Scientists estimate that more than 26,000 Hectors
dolphins lived around New Zealands shores in the
1970s. Today, it is thought that just 7270 remain
which is less than one third of the 1970s population.
The Hectors dolphin was given threatened species
status by the Department of Conservation in
Today, Hectors dolphins are listed on the World
Conservation Unions Red List as endangered, and
are among the most rare of the worlds 32 marine
dolphin species. The Cetacean Specialist Group of
the Species Survival Commission of IUCN, the world
scientific experts on cetacean conservation, have
assessed Hectors dolphin as a threatened species
of vulnerable status using the agreed threatened
species criteria. Research shows that even if all
available actions were implemented today, by 2055
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.
Decrease of population from 19702010
Hectors dolphins mortality (19692009)
Mortality of Hectors dolphin in gill-net fisheries is a
threat to local populations throughout its range. This
population viability analysis extends previous work by
exploring a wider range of fishing levels and population
growth rates, by incorporating year to year and
environmental variability and by reporting results for
smaller population units.
Ten of the 16 populations are likely to continue to
decline, five are indefinite, and one is likely to increase.
All populations subjected to high fishing effort are
declining. The only population predicted to increase
is partly protected by a marine mammal sanctuary
that was created in 1988, which reduces the amount
of gill net fishing. Conservation measures are most
urgently needed for the highly threatened North Island
population, in particular the dolphins at the northern
and southern end of this range.
Reducing fisheries mortality to levels approaching zero
shows the strongest promise of meeting national and
international guidelines for managing dolphin bycatch,
with a 59% probability of reaching 50% of estimated
1970 population size by 2050.
Such very small population of Hectors dolphins have a high extinction risk simply due to stochastic factors.
Marine and Freshwater research, 2010
Atlantic spotted Dolphin Whiteside dolphin
2.5m 2.5m 2.5m
Shorter length, shorter life
Hectors Dolphins are one of the smallest
dolphins in the world. As adults the Hectors
Dolphin has a length of 1.5 meters and weigh
in at only 50 kilograms.
Hectors dolphins do not live as long as others,
the smaller the species, the shorter the lifespan.
Out of more than 80 Hectors 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
species. By contrast, larger dolphins such as the
bottlenose live to between 25 and 50 years.
A dolphins age is estimated from the layers in a
cross section of tooth. Because of their small size,
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 Hectors dolphin are about
the size of a humans, and when trapped in one,
it takes about the same length of time for them to
drown as it would a person.
Population of different breeds
New zealand Hectors dolphin populations are more susceptible to extinction than other species.
Zoology and wildlife conservation, 1998
Number of reproductions
Hookers Sea Lion
50 yrs48 yrs
The slow rate of Hectors dolphins reproduction
makes their populations vulnerable. Females arent
sexually mature until they are between seven
and nine years old, that would be equivalent to a
human not being able to reproduce until they are
about 30 years old.
They produce just one calf every two to four years.
One female might only produce four calves in her
20 year lifetime and this is just enough to replace
the number of dolphins that die naturally. Hectors
dolphins are having a very difficult time replacing
members of their population as fast as they are
The gestation period for Hectors Dolphin is believed
to be about a year. Calves are born in spring and early
summer, November to February. The calf starts eating
solid food at about 6 months of age, but stays with its
mother for a full year. Minimum calving intervals range
from 2 4 years, but the mother does not conceive
again until the calf is independent.
Life expectancy of endangered species
Calves are oldenough to live on
73% Set net
Population declining threats
Dolphins and people have shared our shores and
bays for centuries. In recent years, there has been a
worldwide increase in awareness of marine mammals
and a greater desire to protect them.
Set net fishing poses a majo