HOME

TheInfoList



OR:

The New Zealand sea lion (''Phocarctos hookeri''), once known as Hooker's sea lion, and as (for both male and female) or (male) and (female) in
Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the Co ...
, is a species of
sea lion Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. ...
that is
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to New Zealand and primarily breeds on New Zealand's subantarctic
Auckland Auckland ( ; ) is a large metropolitan city in the North Island of New Zealand. It has an urban population of about It is located in the greater Auckland Region, the area governed by Auckland Council, which includes outlying rural areas and ...
and Campbell islands, and have in recent years been slowly breeding and recolonising around the coast of
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
's
South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...
and Stewart islands. The New Zealand sea lion numbers around 12,000 and is one of the world's rarest sea lion species. They are the only species of the genus ''Phocarctos''.


Physiology and behaviour

New Zealand sea lions are one of the largest New Zealand animals. Like all
otariids An eared seal, otariid, or otary is any member of the marine mammal family Otariidae, one of three groupings of pinnipeds. They comprise 15 extant taxon, extant species in seven genus, genera (another species became extinct in the 1950s) and are ...
, they have marked
sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
; adult males are long and weigh , while adult females are long and weigh . At birth, pups are long and weigh ; 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. The New Zealand sea lion's terrestrial behaviour is unique among other pinniped species. In the breeding season, female New Zealand sea lions gradually move inland with their pups to protect them from harassment by males, wind, storms, and potential parasitic infections. They can move up to inland, from sandy beaches to tall grasses, and into forests. They are the only pinniped species known to disperse far inland and have a preference for forests.


Distribution

The main breeding populations are at the Auckland and Campbell Islands in the New Zealand subantarctic, where approximately 99% of the species' annual pup production occurs. There are currently three functioning breeding rookeries on the Auckland Islands. Most sea lions are born on Dundas Island. A smaller rookery exists at Sandy Bay on Enderby Island and the smallest rookery is on Figure of Eight Island. An even smaller rookery at South East Point on Auckland Island appears to now have been abandoned. The other major breeding area is the Campbell Islands. Historically, New Zealand sea lions were distributed all over mainland New Zealand and Stewart Island, but were
extirpated Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions. Local extinctions mark a chan ...
from these areas due to human hunting activities. For the first time in over 150 years, sea lions began breeding again on the South Island coast in 1993, on the
Otago Peninsula The Otago Peninsula () is a long, hilly indented finger of land that forms the easternmost part of Dunedin, New Zealand. Volcanic in origin, it forms one wall of the eroded valley that now forms Otago Harbour. The peninsula lies south-east of Ot ...
after Mum gave birth. Other small populations of breeding sea lions have recently begun to establish in various parts of the Stewart Island coastline and have been observed on the Catlins coast south of the Clutha River. Recent DNA information indicates the New Zealand sea lion is a lineage previously restricted to subantarctic regions. Somewhere between 1300 and 1500 AD, a genetically distinct mainland lineage was wiped out by the first Maori settlers, and the subantarctic lineage has since then gradually filled the ecological niche. It has been inferred from
midden A midden is an old dump for domestic waste. It may consist of animal bones, human excrement, botanical material, mollusc shells, potsherds, lithics (especially debitage), and other artifacts and ecofacts associated with past human oc ...
s and ancient DNA that a third lineage was made extinct at the
Chatham Islands The Chatham Islands ( ; Moriori language, Moriori: , 'Misty Sun'; ) are an archipelago in the Pacific Ocean about east of New Zealand's South Island, administered as part of New Zealand, and consisting of about 10 islands within an approxima ...
due to predation by the
Moriori people The Moriori are the first settlers of the Chatham Islands ( in Moriori; in Māori). Moriori are Polynesians who came from the New Zealand mainland around 1500 AD, which was close to the time of the shift from the archaic to the clas ...
.


Diet and predation

New Zealand sea lions are known to prey on a wide range of species including
fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
such as Antarctic horsefish and
Patagonian toothfish The Patagonian toothfish (''Dissostichus eleginoides''), also known as Chilean sea bass, mero, and icefish, is a species of notothen found in cold waters () between depths of in the southern Atlantic, Pacific, and Indian Oceans and Southern ...
,
cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
s (e.g. New Zealand arrow squid and yellow octopus),
crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s,
seabird Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...
s and other
marine mammal Marine mammals are mammals that rely on marine ecosystems for their existence. They include animals such as cetaceans, pinnipeds, sirenians, sea otters and polar bears. They are an informal group, unified only by their reliance on marine enviro ...
s, and even New Zealand fur seals. 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 preyed on by
great white shark The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocea ...
s, with 27% showing evidence of scarring from near-miss shark attacks in an opportunistic study of adult New Zealand sea lions at Sandy Bay, Enderby Island.


Status

New Zealand sea lions are considered the most threatened sea lion in the world. The species' status is largely driven by the main breeding population at the Auckland Islands, which declined by ~50% between 2000 and 2015. The 2013 sea lion pup production count on the Auckland Islands showed the number of pups born on the islands has risen to 1931, from the 2012 figure of 1684 (dead pups are also counted, since the annual pup count is used to assess the population of breeding females, but not future births when the counted pups mature). The 2013 number was the highest in five years. The Campbell Island population 'appears to be increasing slowly' and births here comprise ~30% of the species' total. The Otago and Stewart Island sea lion populations are currently small, though increasing. Population estimates for the whole species declined from ~15,000 in the mid-1990s to 9,000 in 2008 (based on the number of pups born). In 2010, the
Department of Conservation Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...
—responsible for marine mammal conservation—changed the
New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had s ...
ranking from Nationally Endangered to Nationally Critical. The Department of Conservation estimates that Auckland Islands' sea lions, nearly 80% of the total, could be functionally extinct by 2035. However, the New Zealand Ministry for Primary Industries considers research on which this prediction is based is low quality and 'should not be used in management decisions'. In 2015, the
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...
(IUCN) changed the classification of this species to "Endangered", based on low overall population size, the small number of breeding populations and the projected trend of the Auckland Islands breeding population. In 2019, the New Zealand sea lion's status was found to have improved and they are now "Nationally Vulnerable". Their overall rate of population decline has slowed in most breeding locations and Stewart Island was officially recognised as a new breeding colony in 2018. Their global IUCN status remains "Endangered".


Threats


Subsistence hunting and commercial sealing

Subsistence hunting and commercial harvest of sea lions greatly reduced the breeding range and population size of New Zealand sea lions between the 13th and 19th Centuries. In 1893, sealing for both New Zealand sea lions and
New Zealand fur seal ''Arctocephalus forsteri'' (common names include the Australasian fur seal, South Australian fur seal, New Zealand fur seal, Antipodean fur seal, or long-nosed fur seal) is a species of fur seal found mainly around southern Australia and New Z ...
s was prohibited by law in New Zealand.


Commercial fishery bycatch

In the 1990s, as the volume of squid fishing around the Auckland Islands increased, numbers of sea lions were captured as bycatch and drowned in the squid trawl nets. The government uses a modelling system to set a fishing-related mortality limit (FRML) each year. If the limit is predicted to be exceeded, the Minister of Primary Industries may close the fishery. The last time the FRML was exceeded was in 2000, though a number of closures occurred in the 1990s. In late February 2013, the first observed sea lion mortalities in the Auckland Island squid fleet in three years occurred. Juvenile sea lions slipped through the grid at the opening of the net into its cod end. The 23-cm grid aperture is designed to hold adult sea lions in the SLED (sea lion exclusion device) and yet still allow squid to pass into the net. In 2013, one adult female was taken as incidental bycatch. In August 2013, the seasonal southern blue whiting fleet captured 21 male sea lions in fishing grounds more than 100 km off the Campbell Islands. Four were released alive. No captures were reported by government observers the year before. The government responded to the captures by requesting the vessels try sea lion exclusion devices (SLEDs) to reduce this bycatch. The estimated captures in the 2014 season were 11.58% of the FRML.Ministry for Primary Industries, SQU6T Weekly Report for week ending 29 June The proportion of vessels in the Auckland Island squid fishery with government observers has increased over the years, providing independent reports of bycatch based on observation rather than computer model estimates. During the 2014 season, the observers' coverage was of 84% of tows. In the concluded 2014 season, two sea lions were reportedly captured in the fishery.


Sea lion exclusion devices

In 2001, the sea lion exclusion device (SLED) was introduced into the Auckland Island squid fishery to reduce sea lion bycatch. Conservation advocates have supported SLED use to protect other marine animals or sharks. Since 2007, all vessels in the Auckland Islands fishery have been equipped with SLEDs. Some scientists do not believe sea lions survive the interaction with a SLED, though the Ministry for Primary Industries (MPI) believes the direct effect of fishing-related mortality on the sea lion population is minimal. MPI has concluded that a sea lion has an 85% chance of escaping the SLED and a 97 per cent probability of surviving a SLED escape, though it says this estimate may be 'mildly pessimistic'.


Food limitation

Food availability is a well-known, major cause of population change in
pinniped Pinnipeds (pronounced ), commonly known as seals, are a widely range (biology), distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant taxon, extant families Odobenidae (whose onl ...
species. The Auckland Islands population has displayed numerous indicators of food limitation during the recent decline in breeder numbers, including: poor maternal condition, delayed maturation, years with very low pupping rate, low survival of pups born and long-term shifts in diet composition. Starvation was provisionally identified as cause of mortality for 62% of pups necropsied at Campbell Island in 2015, when 58% of all pups born were estimated to have died in the first month of life.


Disease

Though the Auckland Island sea lion pup production is highly variable, a decline trend for some years followed the outbreak of an introduced bacterial disease caused by a ''
Campylobacter ''Campylobacter'' is a type of bacteria that can cause a diarrheal disease in people. Its name means "curved bacteria", as the germ typically appears in a comma or "s" shape. According to its scientific classification, it is a genus of gram-negat ...
'' species in 1998 which killed an estimated 53% of newborn pups and 20% of adult females. In 2002, another probably introduced bacterial disease caused by ''
Klebsiella pneumoniae ''Klebsiella pneumoniae'' is a Gram-negative, non-motile, encapsulated, lactose- fermenting, facultative anaerobic, rod-shaped bacterium. It appears as a mucoid lactose fermenter on MacConkey agar. Although found in the normal flora of the mo ...
'' killed 32% of pups, and in 2003 another 21% of the pups. Since 2002, ''K. pneumoniae'' bacteria have caused significant mortality in the sea lion pups at Enderby Island. Infected pups have meningitis, as well as
sepsis Sepsis is a potentially life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage of sepsis is followed by suppression of the immune system. Common signs and s ...
. On 12 March 2014, the Conservation Minister Nick Smith was quoted as saying an "excessive focus on fishing bycatch" existed and 300 pups had died the previous summer from an as yet unidentified disease.


Mainland threats

The mainland population was estimated to reach 1000 animals by 2044, leading to issues of '
marine protected area A marine protected area (MPA) is a protected area of the world's seas, oceans, estuaries or in the US, the Great Lakes. These marine areas can come in many forms ranging from wildlife refuges to research facilities. MPAs restrict human activity ...
s, local fishing quotas and numbers management'. New Zealand sea lions are projected to potentially distribute all around mainland New Zealand, but they face potential human conflicts, especially due to their unique inland movement behaviour. New Zealand sea lions have been hit by cars on roads, and deliberately killed, harassed, and clubbed. There have also been incidents of disturbance from domestic dogs. Infrastructure such as roads and fences also pose as barriers to their inland movement. Females and pups on the mainland have also adapted to commercial
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...
plantations, which are privately-owned lands. In order ensure the protection of New Zealand sea lions, the Department of Conservation works to engage with local communities and spread awareness on this species' recolonisation and behaviour.


See also

*
Australian sea lion The Australian sea lion (''Neophoca cinerea''), also known as the Australian sea-lion or Australian sealion, is a species of sea lion that is the only endemic pinniped in Australia. It is currently Monotypic taxon, monotypic in the genus ''Neopho ...


References


External links


New Zealand sea lion
at the
Department of Conservation Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

Encyclopedia of New Zealand
- New Zealand sea lion *ARKive�

{{Authority control
New Zealand sea lion The New Zealand sea lion (''Phocarctos hookeri''), once known as Hooker's sea lion, and as (for both male and female) or (male) and (female) in Māori, is a species of sea lion that is endemic to New Zealand and primarily breeds on New Zeala ...
Fauna of the Campbell Islands Fauna of the Auckland Islands Fauna of the South Island Pinnipeds of New Zealand
New Zealand sea lion The New Zealand sea lion (''Phocarctos hookeri''), once known as Hooker's sea lion, and as (for both male and female) or (male) and (female) in Māori, is a species of sea lion that is endemic to New Zealand and primarily breeds on New Zeala ...
New Zealand sea lion The New Zealand sea lion (''Phocarctos hookeri''), once known as Hooker's sea lion, and as (for both male and female) or (male) and (female) in Māori, is a species of sea lion that is endemic to New Zealand and primarily breeds on New Zeala ...
Endemic fauna of New Zealand Endemic mammals of New Zealand