hector's dolphin

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Endangered Animal - Hector's Dolphin

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  • 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

    Introduction

    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.

  • The problem

    Unprotected distribution

    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.

    WWF, 2010

  • Population decrease

    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

    December 1999.

    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.

    2010

    2001

    1985

    1970

    5000

    10000

    15000

    14000

    18500

    23000

    27500

    Pop

    ulat

    ion

    of H

    ecto

    rs d

    olph

    in

    Decrease of population from 19702010

  • 25

    Hectors dolphins mortality (19692009)

    50

    75

    100

    125

    1969

    197

    9

    Num

    ber o

    f dol

    phin

    s

    1979

    198

    9

    1989

    199

    9

    1999

    200

    9

    Mortality

    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

  • Striped dolphin

    Hourglass Dolphin

    Atlantic spotted Dolphin Whiteside dolphin

    Rissos Dolphin

    Hectors Dolphin

    1.5m

    1.8m

    2.5m 2.5m 2.5m

    3.5m

    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.

  • 10,000

    50,000

    100,000

    500,000

    1,000,000

    1,500,000

    2,000,000At

    lantic

    Spo

    tted

    Dolp

    hin

    Num

    ber o

    f dol

    phins

    Population of different breeds

    Riss

    os D

    olph

    in

    Whi

    tesid

    e Do

    lphin

    Strip

    ed D

    olph

    in

    Hour

    gla

    ss D

    olph

    in

    Hect

    ors

    Dolp

    hin

    New zealand Hectors dolphin populations are more susceptible to extinction than other species.

    Zoology and wildlife conservation, 1998

  • The causes

    Humpback Whale

    Life expectancy

    Number of reproductions

    Hookers Sea Lion

    Hectors Dolphin

    20 yrs

    23 yrs

    50 yrs48 yrs

    34 yrs

    78 yrs

    Breeding ovulation

    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

    losing them.

    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

  • Year 3

    Year 1

    Year 2

    Calves areborn

    Calves are oldenough to live on

    their own

    JanFeb

    Mar

    Apr

    May

    JunJuly

    Aug

    Sep

    Oct

    Nov

    NovDec

    Nov

    Mating season

    Breeding ovulation

  • 73% Set net

    5% Natural

    0.5%Boat strike

    6.5%Trauma

    1.5%Cray pot

    13.5%Trawler

    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