|A new sub-species of Hectors Dolphin?
[article1] [article2] [petition] [DNA research] [survival]
Divers and fishermen have long regarded the Hector's dolphins living along New Zealand's west coast of the North Island, from New Plymouth to the Hokianga Harbour, as a different sub-species because they look different and are much bigger than their southern cousins. Most Hector's dolphins occur around the South Island of New Zealand, living close to the coast while frequenting inlets and fiords.
Two Auckland Univerity students, Franz Pichler and Kirsty Russell have brought new insight in the genetics and ecology of the northern tribe of Hectors Dolphins. Mr Pichler discovered that their DNA was sufficiently different from the southern tribe that they deserve the distinction of a new sub species. Ms Russell studied their ecology, taking many photographs. She discovered that their numbers are too low and their mortality rates too high for survival. NZ Herald article of 16 Oct 1999.
Too many Hectors Dolphins die in monofilament set nets as used for catching bait fish in coastal waters. Concerned with their survival, Ingrid Visser, well known for her studies on orcas, broadcast a well-documented petition for measures to ensure the survival of this very special sub-species.
South Island Hector's dolphin,
mother and baby.
courtesy of Steve Dawson
Sometimes Kirsty Russell and Franz Pichler wonder if anyone
really cares about the plight of the North Island Hector's dolphin.
There are only about l00 survivors left of the dolphin subspecies, separate
from the South Island Hector's dolphin, which inhabit Auckland west coast
waters. But the two Auckland University students have
to finance much of their research themselves, though they receive some
sponsorship. Last week, on an all-day expedition they
paid for themselves, the pair saw 12 of the dolphins south of the Manukau
Heads. Six of the rare dolphins were riding the swells
and surf off Karioitahi Beach and six more were apparently playing in rough
water at the Port Waikato bar. But the day on the water
searching and collecting genetic material by gently scratching the skin
of the dolphins with plastic pot cleaner pads will cost about $660 when
all the bills come in. Mr Pichler's working on the genetics
of the animals for his PhD, discovered the west coast dolphins to be a
distinct subspecies, perhaps separated from the South Island variety from
the time the North and South Islands were one land mass.
His work has received some sponsorship from the World Wide Fund for Nature
New Zealand but when there is a break in funding the pair put their own
cash into the research or work to raise the money. Mr
Pichler said: "If you receive funding from someone it indicates your work
is important to them. To not receive funding tends to suggest people think,
well, who cares?" "The people of Auckland have this dolphin
population right off the coast— sure it's on the west coast so it's rough
and hard to get to but what's left is an Auckland population — and yet
so much more effort and attention seems to be spent on bottlenose and common
dolphins, which occur worldwide." Deaths of the rare
dolphins are thought to occur as a result of the mammals being hit by boats,
drowning in fishing nets or trawling gear, inbreeding or being poisoned
by toxic manmade pollutants in runoff from the land.
Kirsty Russell has been studying the ecology of North Island Hector's dolphins
and documenting their decline for her MSc. For 18 months
she has photographed their dorsal fins for identification purposes, working
out their habitat preferences, the composition of pods, and reproduction
and death rates. "This kind of information has to be
determined scientifically so we know whether there is a hope for them or
not. I guess I am optimistic because I want them to survive.
If something is done now to protect them there is a possibility they will
survive." Kirsty Russell said. Engineering firm CPS New
Zealand paid petrol costs for her boat, which was partly paid for by Aquapro
International, while NZ Aerial Mapping provided flying time.
But she said much of her research went on her student loan.
"We are trying to get more funding but some organisations believe this
is not a high priority."
New Zealand's only native dolphin, the Hector's dolphin, is now officially
listed as a threatened species, meaning more effort can be put into its
survival. Conservation Minister Sandral Lee won plaudits from conservationists
yesterday when she declared the dolphin threatened under the Marine Mammals
Protection Act. But conservation groups urged her to take further action
to save the North Island Hector's dolphin, a subspecies that lives off
the west coast of Auckland. Hector's dolphins are falling victim to fishing
nets, collisions with boats and pollution. The population numbers between
3000 and 4000, while the North Island variety is down to about 100 and
could be extinct within 50 years.
Ms Lee said the "threatened" listing would provide her with more flexibility in taking steps to ensure the survival of the dolphin. "Hector's dolphin is as unique to the New Zealand environment as the kiwi or kakapo are to our forests."
She said numbers of Hector's dolphins had been increasing since the establishment of the Banks Peninsula marine mammal sanctuary, which now attracted 10,000 boat-borne tourists a year.Conservationists said a similar sanctuary should be established on the west coast of the North Island. A group of Otago University students has started a petition to ban gill-netting from the Hokianga Harbour to the Whanganui River. Barry Weeber, of the Royal Forest and Bird Protection Society, said the Hector's was probably the world's rarest marine dolphin (there are rarer freshwater dolphins). He said dead dolphins had been found washed ashore with injuries that indicated they had drowned in nets.
1. Hector's dolphins are unique to New Zealand and regarded as threatened by IUCN;
2. The genetic difference between the North Island population and SouthIsland Hector's dolphins is so great, they should be regarded as a separate sub-species; and
3. Estimates show that at the current rate of decline, this population is likely to become extinct in 50 years.
This petition appeals to the New Zealand Government to call an immediatehalt to all gillnetting along the west coast of the North Island (in particularfrom Hokianga Harbour to the Wanganui River), to allow the recovery of the North Island population of New Zealand's Hector's dolphins. It is considered that population levels are too low to experiment with techniques to reduce by catch levels and that a ban on all gillnetting is the only way to ensure the survival of this population of Hectors dolphins.
Ingrid Visser (email@example.com)
The Orca Project, 'Aorangi', Matapouri Road, RD 3, Whangarei, New Zealand. mobile 025 727 627
PLEASE NOTE TEMP Phone number: 9 43 43 043
Geographic Isolation of Hector's Dolphin
Populations Described by Mitochondrial DNA Sequences
To describe the genetic structure of Hector's Dolphin (Cephalorhynchus hectori) populations, we used the polymerase chain reaction to amplify and sequence a 360 base-pair fragment of the mitochondrial DNA control region from 34 beachcast or gillnet-caught specimens. Variation in these sequences identified 11 distinct haplotypes differing form one another by .28 -1.67% and by an average of 4.47% from the closely related Commerson's dolphin. The genealogical relationship of these haplotypes showed a strong concordance with the geographic origins of the samples. An analysis of variance modified for molecular data showed that 74% of the sequence variation could be explained by the three primary sampling regions: North Island, the west coast of the South Island, and the east coast of the South Island. Such a marked segregation of maternal lineages across a small geographic range is unusual among cetaceans. The low rate of female dispersal, as indicated by this mitochondiral DNA structure, could increase the vulnerability of local populations to extinction due to fisheries-related mortality.
Pichler, F.B., Dawson, S.M., Slooten, E. and Baker, C.S. 1998. Geographic Isolation of Hector's Dolphin Populations Described by Mitochondiral DNA Sequences. Conservation Biology. 12: 676-682.
A sensitivity analysis to guide research
and management for Hector's dolphin
Hector's dolphin (Cephalorhynchus hectori) is an uncommon endemic of New Zealand which is suspected to be in decline due to entanglement mortality. However, uncertainty in available data has led to a dispute between the New Zealand Ministry of Fisheries and the New Zealand Department of Conservation over the status of this species. We use a density-dependent deterministic model to predict the future abundance and geographic distribution of Hectorms dolphin under different scenarioms of fisheries management. We then examine the sensitivity of this model to a number of parameters for which few or no data are available. We find that two populations of Hectors dolphin are predicted to decline in the future even when the most optimistic parameter estimates are used. The status of the third population is dependent on the estimate of maximum annual population growth rate. Because of the dependence of final abundance estimates of entanglement mortality rates and maximum population growth rate, research effort should be concentrated on estimating these parameters.
Martien, K.K., Taylor, B.L., Slooten, E. and Dawson, S. 1999. A sensitivity analysis to guide research and management for Hectors dolphin. Biological Conservation 90 (1999) 183-191.