ENDANGERED SPECIES MONDAY | PHOCARCTOS HOOKERI
This Monday’s endangered species (E.S.P.) article I’ve chosen to document on the New Zealand sea lion. Image: New Zealand Sea Lion. Credits: Tui De Roy.
Listed as (endangered) the species was identified by Dr Gray back in 1866. Dr Gray John Edward Gray, FRS (12 February 2021 – 7 March 2020) was a British zoologist. He was the elder brother of zoologist Dr George Robert Gray and son of the pharmacologist and botanist Dr Samuel Frederick Gray (1766–1828).
Dr Gray was Keeper of Zoology at the British Museum in London from 1840 until Christmas 1874, before the Natural History holdings were split off to the Natural History Museum published several catalogues of the museum collections that included comprehensive discussions of animal groups as well as descriptions of new species. He improved the zoological collections to make them amongst the best in the world.
Scientifically identified as the Phocarctos hookeri the species was listed as vulnerable from 1994-2008. Unfortunately due to continued population declines the New Zealand seal is now bordering complete extinction within the wild (and things really aren’t looking good neither) Endemic to Australia (Macquarie Is.); and New Zealand (South Is.), the species is also native to the Pacific North West.
To date there is estimated to be no fewer than 3,031 mature individuals remaining within the wild. New Zealand sea lions are one of the largest New Zealand animals. Like all otariids, they have marked sexual dimorphism; adult males are 240–350 cm long and weigh 320–450 kg and adult females are 180–200 cm long aMnd weigh 90–165 kg. At birth, pups are 70–100 cm long and weigh 7–8 kg; the natal pelage is a thick coat of dark brown hair that becomes dark gray with cream markings on the top of the head, nose, tail and at the base of the flippers.
Adult females’ coats vary from buff to creamy grey with darker pigmentation around the muzzle and the flippers. Adult males are blackish-brown with a well-developed black mane of coarse hair reaching the shoulders. New Zealand sea lions are strongly philopatric.
Image: New Zealand Sea Lion Pup. Credits: NZ Fur Seals.
Back in 2012 populations of New Zealand sea lions “were estimated to be standing at a population count of 12,000 mature individuals”. However since that count took place, from (2014) populations have ‘allegedly plummeted’ to all new levels although there doesn’t appear to be any evidence as to why the species suddenly declined - fish trawling and disease have been noted though!.
Like the Maui’s dolphin, the sea lion has come under intense scrutiny this year after research showed its numbers had halved since 1998. It has been classed as nationally critical and if its decline is not stemmed will be extinct within 23 years. A bacterial infection severely reduced breeding in 1997-98, and the species has failed to recover.
Its decline has been compounded by deaths due to squid fisheries, which trawl at a similar depth to the sea lions’ hunting grounds. Conservation groups call the population decline “a national emergency and are calling on stricter by-catch limits and a change in fishing methods”.
BACK IN 2012 THE NEW ZEALAND HERALD REPORTED THE FOLLOWING
In a country with 2800 threatened species, conservation in New Zealand is often about picking winners. The Department of Conservation’s budget and energy can extend only to active interventions for 200 of these endangered species.
Whether a species is protected depends on funding, community input, national identity and research. DoC spokesman Rory Newsam says interventions are often made because the department believes it can “get the most bang for its buck”. But animals and plants are not always invested in because they have a greater chance of survival.
The kakapo receives a relatively large chunk of funding despite being functionally extinct on the mainland. Some ecologists argue too much is spent rescuing the rare parrot, while more crucial parts of our ecosystem are left behind. But the kakapo is protected because it is a charismatic species and the public considers it integral to New Zealand’s ecological identity.
Conservationists say kakapo are a window to New Zealand’s history. They are believed to have inhabited the Earth for millions of years. To kill them off in a fraction of that time is an indictment on the way we live.
Image: New Zealand Sea Lion. Image Credits One Newz.
New Zealand sea lions are known to predate on a wide range of prey species including fish (e.g. hoki and red cod), cephalopods (e.g. New Zealand arrow squid and yellow octopus), crustaceans, seabirds and other marine mammals. Studies indicate a strong location effect on diet, with almost no overlap in prey species comparing sea lions at Otago Peninsula and Campbell Island, at the north and south extents of the species’ breeding range. New Zealand sea lions are in turn predated on by great white sharks, with 27% showing evidence of scarring from near-miss shark attacks in an opportunistic study of adult NZ sea lions at Sandy Bay, Enderby Island.
Image: Dead New Zealand Sea Lion in Fishing Net.
Since 2012 New Zealand conservationists, and the public community have been calling on the New Zealand government to do everything they possibly can to preserve this species. Unfortunately as you can see above fishermen are still accidentally killing the species off. As the species is protected under law and listed as endangered, the New Zealand government must take action against these perpetrators, otherwise extinction will most certainly occur.
The Maori people of New Zealand have traditionally hunted Sea Lions, presumably since first contact, as did Europeans upon their arrival much later. Commercial sealing in the early 19th century decimated the population in the Auckland Islands, but despite the depletion sealing continued until the mid-20th century when it was halted.
Commercial sealing in the early 19th century decimated the New Zealand Sea Lion population in the Auckland Islands, but despite the depletion sealing continued until the mid-20th century. The population has yet to fully recover from the period of over exploitation. At the present time, New Zealand Sea Lions have a highly restricted distribution, a small population, and nearly all of the breeding activity is concentrated in two subantarctic island groups. This restricted and small breeding population in combination makes them vulnerable to disease outbreaks, environmental change, and human activities.
The commercial Arrow Squid trawl fishery near the Auckland Islands reported their first New Zealand Sea Lion bycatch mortalities in 1978. Reported or estimated mortality between 1995 and 2007 averaged 92 animals annually (range 17-143) which was 3.7% of the estimated number of mature individuals in the Auckland Island area. Of particular concern is that most bycatch animals are females (up to 91%). New Zealand Sea Lions are also incidentally caught in other trawl fisheries around the Auckland and Campbell Islands.
Apart from direct mortality, competition and habitat modification caused by fishing activity may also be impacting New Zealand Sea Lion foraging areas. Epizootic outbreaks at the Auckland Islands in 1998, 2002, and 2003 led to more than 50%, 33%, and 21% early pup mortality respectively, and were also responsible for the deaths of some animals from other age classes during 1998.
The source of the suspected bacterial agent and cause of the outbreak and subsequent mortality for the 1998 outbreak are unknown, however the 2002 and 2003 outbreaks have been identified as being caused by Klebsiella pneumoniae.
The future of the New Zealand sea lion doesn’t look good at all. I highly suspect that we’re going to lose the species within 10-20 years (if that). More needs to be done to preserve the species habitat and its current fishing grounds as well as protecting from bacterial outbreaks. Failing this the species will be extinct within 10-20 years max. I am highly doubtful here, which is very rare for me to speak about.
Thank you for reading.
Dr Jose C. Depre. PhD. MEnvSc. BSc(Hons) Botany, PhD(NeuroSci) D.V.M.
Environmental, Botanical & Human Scientist.