Meet the Hector's Dolphin
Neptune's Note X
Name: The Hector’s dolphin goes by many names: Māori names, nicknames, and other names that are just terms of endearment. But the name they go by most comes from one Sir James Hector. James Hector was a Scottish naturalist and the first to examine specimens of the dolphin in the 1800s, hence he put his own name to it. I usually find this an irritatingly dull way to name a species but call me fickle, James Hector has quite an interesting tale.
Born in Edinburgh, Hector studied medicine at university and got himself a spot on the Palliser Expedition to Canada in 1857. As they were exploring a mountain pass in the Canadian Rockies the group's pack horses fell into the river. Amidst the chaos of pulling them out to safety Hector was kicked in the chest and thus Kicking Horse Pass and Kicking Horse River were named. In later years, he secured another scientific position which took him to Dunedin1, New Zealand. Here, he worked as a geologist2 turned zoologist which led to the examination of certain species and in turn, the names Hector’s beaked whale and Hector’s dolphin, among others.
Anyway, I digress. There are several Māori names for the lovely little Hector’s dolphin, including taonga, tupoupou and tutumairekurai the latter of which is the most commonly used and means ‘ocean dweller’. Other names are ‘Mickey Mouse dolphins’ because of the shape of their dorsal fins; ‘hobbit’ dolphins because of their size and home country; ‘Māui dolphins’ which are actually a sub-species and ‘little pied dolphins’; which is probably due to their piebald colour but is also super cute. Are we not all guilty of seeing a sweet animal and giving it an unreasonable amount of silly nicknames?
Family: Delphinidae, which includes moderate to small-sized toothed whales such as the white-beaked dolphin, the pilot whale and the killer whale.
Genus: The genus, Cephalorhynchus, consists of just four species from within the dolphin family. Similarities between this genus besides their physical features is that they choose to reside in distinct geographical locations.
Location: The Hector’s Dolphin is the only cetacean endemic to New Zealand. Found in the coastal waters off the South Island, while the subspecies, the Māui dolphin, prefer the western coast of the North Island. Both species have a preference for shallow waters less than ten miles from the shore and are most definitely creatures of habit as they tend to stay in the same 50 km of coastline with some individuals recorded in the same area for over 20 years. Kiwis through and through.
Population: Hector’s dolphins are only capable of a slow population growth as they become sexually mature quite late in relation to their short lifespan (22 years on average). Females do calve every 2-3 years and will have between 4-7 calves in their lifetime but the mortality rate for calves in the first six months of their life is as high as 36%. This, combined with the growing anthropogenic threats they face explains the small population, with estimates varying widely between 7,000 and 15,000 individuals.
Status: According to the IUCN Red List Hector’s dolphins are officially endangered but this record hasn’t been updated since 2008. Māui dolphins were assessed much more recently and were given a critically endangered status. There are believed to be just 55 Māui dolphins left.
Weight: Between 55 and 60 kg depending on the sex.
Length: Mature adults have a maximum length of around 1.5 metres. Teeny-tiny, basically.
Anatomy: Aside from the obvious being that they’re absolutely precious, the Hector’s dolphins most distinctive feature is its rounded dorsal fin which does look like a Mickey Mouse ear. They also have beautiful colouring with distinct black facial markings which extend down their fins, merging into grey with a creamy white belly but black streaked tail. Their short stocky bodies and no pronounced beak discern them from several other dolphin species and they’re slightly more petite than their North Island Māui neighbours.
Diet: Hector’s dolphins have a varied appetite as they select their prey based on size rather than species. It has been noted that they do avoid particularly spiny fish. Their diet mainly consists of red cod, stargazer, squid, and yellow-eyed mullet and they use echolocation to source food.
Social habits: Most often found in pods of five or less, these groups are highly segregated by sex. There is also a high level of fluidity among associations with other individuals, meaning they do not form particularly strong bonds with one another, so if one pod crosses paths with another pod nobody will hold a grudge if everybody gets mixed up and goes their separate ways with a completely new set of friends. The Hector’s dolphin is basically that one friend we all have who’s friends with everybody but in dolphin social circles it’s known as ‘fission-fusion’. Despite their indifference to any one individual they are very social creatures, as most dolphins are. When they get together the encounters are marked by energetic acrobatics, loud and excitable behaviour which all looks quite boisterous but is usually a performance to attract a mate. Given that they live in highly segregated pods they have to seize their opportunities.
Reproduction: Females will typically calve every 2-3 years during the spring and summer months. Baby Hector’s are weaned at around one year old but the mortality rate for calves up to six months old is 36%. Currently, more Hector’s dolphins die in fishing nets than are born.
Unique facts:
They are the smallest and rarest dolphins in the world.
Newborn Hector’s dolphins are so small they are often described as rugby balls with flippers.
They may look exactly like their northern cousins but Hector’s and Māui dolphins are physically and genetically different, as was officially established in 2002. Before this, Māui dolphins were known as North Island Hector’s.
Threats they face: Hector's dolphins face multiple dangers that threaten their survival, one being the natural predation by sharks such as the broadnose sevengill, great white, and blue shark. However, the most significant danger comes from human activities, bycatch most significantly. Their accidental capture in fishing nets, particularly gillnets and trawls, is the leading cause of mortality in Hector's. These nets, often undetectable by dolphins due to their fine mesh, result in fatal injuries from entanglement and suffocation. Frequent entanglement not only results in immediate fatalities but also contributes to their low genetic diversity, as the deaths often exceed the annual birth rate, weakening the population's resilience and ability to recover.
Additionally, coastal development and seabed mining devastate their habitats, while pollution, including the proposed exploration for oil and gas, taints their waters, posing severe health risks. Boat strikes further endanger these dolphins too due to their proximity to shorelines. Despite increased restrictions on fisheries and enhanced management efforts, Hector's dolphins' numbers have dwindled to less than a quarter of their population since the 1970s. This decline underscores the critical need for better conservation strategies so we can save the tiniest dolphin in the world.
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Amie 🐋
Dunedin comes from the Gaelic name for Edinburgh, Dùn Èideann. I’ve been to Dunedin and I cannot think of a finer place to go and with a finer dream than to study the flora and fauna of that beautiful country.
Interestingly, his work led to the first geological map of New Zealand.
These magnificent creatures are far better than us.
I often wish there were more of them and less of us. We've brought nothing but ill to the Ocean and its life.