Animal Diversity Web

Ge­o­graphic Range

New Zealand sea lions, also known as Hooker’s sea lions, in­habit the south­ern stretches of New Zealand’s ter­ri­tory in the Pa­cific with colonies reach­ing as far north as the Foveaux Straight and as far south as Mac­quarie Is­land. How­ever, the vast ma­jor­ity of breed­ing oc­curs among the Auck­land Is­lands, with a scat­ter­ing of breed­ing colonies in­hab­it­ing the Camp­bell Is­lands. The pop­u­la­tion is es­ti­mated to be be­tween 10,000 and 13,000 total in­di­vid­u­als. Al­though New Zealand sea lions were thought to have dis­ap­peared from the main­land 200 years ago due to human hunt­ing, in 1993 it was re­ported that a sin­gle sea lion had breed on the main­land penin­sula. ("New Zealand Sea Lion", 2010; Louise Chil­vers, et al., 2007)

• Biogeographic Regions
• oceanic islands
  • native

Habi­tat

New Zealand sea lions are com­fort­able in a wide range of habi­tats, from 400 m above sea level through the hills, forests, and fields of the local is­lands to dives of up to 600 m below sea level. Yet, the ma­jor­ity of in­di­vid­u­als pre­fer to re­main on sandy beaches and hunt pri­mar­ily at depths no greater than 200 m below sea level. When breed­ing fe­males will seek shel­ter in the in­land veg­e­ta­tion and, when nec­es­sary, they will hunt main­land birds and their nests. ("New Zealand Sea Lion", 2010; Char­teris, et al., 2008; Mal­oney, et al., 2009)

• Habitat Regions
• polar
• saltwater or marine

• Aquatic Biomes
• coastal

• Range elevation

  400 (high) m

  1312.34 (high) ft

• Range depth

  600 (high) m

  1968.50 (high) ft

Phys­i­cal De­scrip­tion

New Zealand sea lion males have a de­fined mane around their shoul­ders and a dark brown or black color. Males reach be­tween 2.4 and 3.5 m in length and weigh be­tween 200 and 400 kg. Con­versely, fe­males are a much lighter grey and some are even yel­low with some darker shades around the flip­pers. Fe­males are also sig­nif­i­cantly smaller reach­ing only be­tween 1.6 and 2 m in length and weigh­ing be­tween 100 and 160 kg. Pups are typ­i­cally brown in ap­pear­ance with young males re­sem­bling fe­males until full mat­u­ra­tion. This species also fea­tures a very short, blunt head with a length to width ratio of 2:1, com­pared to an av­er­age ratio for fur seals and sea lions of 3:1. ("New Zealand Sea Lion", 2010; Clark, 1873)

New Zealand sea lions are sim­i­lar to Aus­tralian sea lions in ap­pear­ance, but many dif­fer­ences have sur­faced which are used to dis­tin­guish New Zealand sea lions, not only from Aus­tralian sea lions, but also from most other species of sea lion. It is typ­i­cal for New Zealand sea lions to have a deep con­cave palate (22 mm in males and 14.5 mm in fe­males), a den­tal for­mula of I: 3/2 C: 1/1 Cheek teeth: 6/5, and a smooth cylin­dri­cal pro­jec­tion of the tym­panic bulla. (King, 1960)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently

• Range mass

  100 to 400 kg

  220.26 to 881.06 lb

• Range length

  1.6 to 3.5 m

  5.25 to 11.48 ft

Re­pro­duc­tion

New Zealand sea lions are polyg­y­nous and males are ter­ri­to­r­ial. One dom­i­nant male will oc­cupy a beach in late No­vem­ber and harems of up to 25 fe­males will gather in De­cem­ber. Other bulls will re­main on the perime­ter of the ter­ri­tory oc­ca­sion­ally chal­leng­ing the dom­i­nant male. By late Jan­u­ary, the harems will break up and the bulls will dis­perse. ("New Zealand Sea Lion", 2010)

• Mating System
• polygynous

Breed­ing oc­curs in New Zealand's sum­mer months and is fol­lowed by a ges­ta­tion pe­riod of about 11 months. Fe­males move to a breed­ing beach about 2 days be­fore giv­ing birth. They usu­ally have only one pup at a time and give birth every one to two years. Dur­ing their first year, the pups are com­pletely de­pen­dent on the mother for food and pro­tec­tion. ("New Zealand Sea Lion", 2010; Louise Chil­vers, et al., 2007)

At birth males are larger than fe­males, with males weigh­ing in at about 10.6 kg and fe­males 9.7 kg. (Louise Chil­vers, et al., 2007)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  New Zealand sea lions breed once every one to two years.

• Breeding season

  Mating occurs between ecember to early January.

• Range number of offspring

  1 (high)

• Average number of offspring

  1

  AnAge

• Average gestation period

  11 months

• Average gestation period

  365 days

  AnAge

• Average time to independence

  12 months

• Range age at sexual or reproductive maturity (female)

  3 (low) years

• Range age at sexual or reproductive maturity (male)

  8 to 9 years

Body re­serves for pups are rel­a­tively low at birth. Suck­ling oc­curs for eight to nine days be­fore the mother's first for­ag­ing trip, which tends to last for only two days. A di­rect in­flu­ence on pup mor­tal­ity is male ha­rass­ment; fe­males move pups to in­land veg­e­ta­tion six weeks after birth, pre­sum­ably to pro­tect them from adult males. ("New Zealand Sea Lion", 2010; Louise Chil­vers, et al., 2007)

• Parental Investment
• precocial
• female parental care

Lifes­pan/Longevity

New Zealand sea lions are not for­mally kept in cap­tiv­ity and lit­tle is known about their lifes­pan. How­ever, it is es­ti­mated that the max­i­mum lifes­pan for both males and fe­males is about 23 years. ("New Zealand Sea Lion", 2010)

• Range lifespan
  Status: wild

  23 (high) years

Be­hav­ior

New Zealand sea lions are a so­cial species, but not mi­gra­tory. Track­ing of fe­males has shown that they do not travel be­tween the breed­ing sites in the Auck­land Is­lands and the Camp­bell Is­lands. Their only move­ment is be­tween the beaches under the con­trol of the bulls with whom they breed and the birthing beaches. ("New Zealand Sea Lion", 2010; Mal­oney, et al., 2009)

Male New Zealand sea lions have so­cial hi­er­ar­chies. The dom­i­nant ter­ri­to­r­ial male has breed­ing rights leav­ing ju­ve­nile and bach­e­lor males mostly ex­cluded from mat­ing. ("New Zealand Sea Lion", 2010)

• Key Behaviors
• natatorial
• motile
• sedentary
• territorial
• social
• dominance hierarchies

Home Range

In order to feed, New Zealand sea lions might travel up to 175 km from its local coast. ("New Zealand Sea Lion", 2010)

Com­mu­ni­ca­tion and Per­cep­tion

New Zealand sea lion com­mu­ni­ca­tions have not been de­scribed, but is widely stud­ied in their pop­u­lar rel­a­tives, Cal­i­for­nia sea lions. For Cal­i­for­nia sea lions, the most com­mon form of com­mu­ni­ca­tion is vocal. Males, in par­tic­u­lar, use vocal com­mu­ni­ca­tion to in­di­cate ter­ri­to­r­ial own­er­ship, sex­ual readi­ness, and readi­ness to fight. Fe­males use vocal cues to com­mu­ni­cate alarm and readi­ness to suckle to their pups. Pups have an alarm vo­cal­iza­tion as well as a vo­cal­iza­tion to in­di­cate hunger. (Pe­ter­son and Bartholomew, 1969)

• Communication Channels
• acoustic

• Perception Channels
• tactile
• acoustic
• chemical

Food Habits

New Zealand sea lions are car­niv­o­rous. They pre­dom­i­nately eat arrow squids, but other com­mon prey in­clude red cods, opal­fishes, other small local fishes, oc­to­puses, rays and sharks. Most dives are to less than 200 m and last for four to five min­utes; max­i­mum dives reach 600 m. Im­ma­ture sea lions feed on the same type and size of prey as adults. There have been re­ports of New Zealand sea lions trav­el­ing on land and hunt­ing South­ern Royal Al­ba­tross,. A num­ber of stud­ies have con­cluded that New Zealand sea lions often for­ages and func­tions to its phys­i­o­logic lim­its; this is thought to limit re­pro­duc­tive out­put. ("New Zealand Sea Lion", 2010; Char­teris, et al., 2008; Louise Chil­vers, et al., 2007; Meynier, et al., 2009)

• Primary Diet
• carnivore
  • piscivore
  • molluscivore

• Animal Foods
• birds
• fish
• mollusks
• other marine invertebrates

• Foraging Behavior
• stores or caches food

Pre­da­tion

The only known preda­tors on New Zealand seal lions are sharks and dogs on the main­land. Hu­mans also hunted New Zealand sea lions, but today New Zealand laws pro­tect the species. ("New Zealand Sea Lion", 2010)

• Known Predators

  • sharks (Carcharhiniformes)
  • domesticated dogs (Canis lupus familiaris)

Ecosys­tem Roles

New Zealand seal lions are dom­i­nant preda­tors. They hunt sim­i­larly en­dan­gered species, in­clud­ing the South­ern Royal Al­ba­tross, which wor­ries local sci­en­tists and poses an in­ter­est­ing co­nun­drum. (Char­teris, et al., 2008)

New Zealand seal lions have a mu­tu­al­ist re­la­tion­ship with the red-billed gull. This bird will perch on the back of New Zealand seal lions pick­ing the blowflies and other in­sects from the lion’s back and head. This be­hav­ior is sim­i­lar to that of birds and cat­tle. (Bell, 2008)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no known pos­i­tive ef­fects of New Zealand seal lions on hu­mans.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of New Zealand seal lions on hu­mans.

Con­ser­va­tion Sta­tus

Ac­cord­ing to the New Zealand De­part­ment of Con­ser­va­tion, New Zealand seal lions are listed as crit­i­cal, while IUCN lists the species as vul­ner­a­ble. New Zealand is highly con­cerned about New Zealand seal lions, be­cause of in­ter­ac­tions with local fish­ing ves­sels. They rely on arrow squid for food, but hu­mans fish for this squid, as well. Sim­i­lar to dol­phin in­ter­ac­tions with tuna fish­ing, New Zealand seal lions tend to be a com­mon in­ci­den­tal catch of squid fish­er­men. The New Zealand Gov­ern­ment has put lim­its on the num­bers of New Zealand seal lions that can be caught in fish­ing nets. Once this limit is reached, the fish­ery must close op­er­a­tions for the re­main­der of the sea­son. ("New Zealand Sea Lion", 2010; Kahui, 2011)

An­other cause for con­ser­va­tion con­cern for New Zealand seal lions are bac­te­r­ial epi­demics. Each epi­demic takes out hun­dreds of adults and pups. Sci­en­tists must take this into con­sid­er­a­tion when con­tem­plat­ing fur­ther man­age­ment plans for this species, be­cause the pop­u­la­tion is al­ready lim­ited and has a re­stricted range. ("New Zealand Sea Lion", 2010; Louise Chil­vers, et al., 2007)

• IUCN Red List

  Vulnerable
  More information

• IUCN Red List

  Vulnerable
  More information

Con­trib­u­tors

David Fer­land (au­thor), Michi­gan State Uni­ver­sity, Bar­bara Lun­dri­gan (ed­i­tor), Michi­gan State Uni­ver­sity.

Ref­er­ences

2010. "New Zealand Sea Lion" (On-line). New Zealand De­part­ment of Con­ser­va­tion. Ac­cessed March 12, 2012 at http://​www.​doc.​govt.​nz/​conservation/​native-animals/​marine-mammals/​seals/​new-zealand-sea-lion-rapoka-whakahao/​.

Bell, B. 2008. Mu­tu­al­is­tic and op­por­tunis­tic for­ag­ing by red-billed gull (Larus no­vae­hol­lan­diae) around Hooker's sea lion (Pho­carc­tos hook­eri). No­tor­nis, 55: 224-225.

Char­teris, M., P. Moore, E. Larsen. 2008. Notes on New Zealand mam­mals 8. Pre­da­tion on nest­ing south­ern royal al­ba­trosses Diomedea epo­mophora by New Zealand sea lion Pho­carc­tos hook­eri. New Zealand Jour­nal of Zo­ol­ogy, 35: 201-204.

Clark, J. 1873. On the eared seals of the Auck­land Is­lands. Pro­ceed­ings of the Zo­o­log­i­cal So­ci­ety of Lon­don, 1873: 750-760.

Kahui, V. 2011. A bioe­co­nomic model for Hooker’s sea lion by­catch in New Zealand. The Aus­tralian Jour­nal of Agri­cul­tural and Re­source Eco­nom­ics, 56: 22-41.

King, J. 1960. Sea-li­ons of the gen­era Neophoca and Pho­carc­tos. Mam­malia, 24: 445-456.

Louise Chil­vers, B., B. Robert­son, I. Wilkin­son, P. Duig­nan. 2007. Growth and sur­vival of New Zealand sea lions, Pho­carc­tos hook­eri: birth to 3 months. Polar Biol, 30: 459-469.

Mal­oney, A., B. Louise Chil­vers, M. Haley, C. Muller, W. Roe, I. Deb­ski. 2009. Dis­tri­b­u­tion, pup pro­duc­tion and mor­tal­ity of New Zealand sea lion (Pho­carc­tos hook­eri) on Camp­bell Is­land/Motu Ihupuku, 2008. New Zealand Jour­nal of Ecol­ogy, 33/2: 97-103.

Meynier, L., D. Macken­zie, P. Duig­nan, B. Louise Chil­vers, P. Morel. 2009. Vari­abil­ity in the diet of New Zealand sea lion (Pho­carc­tos hook­eri) at the Auck­land Is­lands, New Zealand. Ma­rine Mam­mal Sci­ence, 25/2: 302-326.

Pe­ter­son, R., G. Bartholomew. 1969. Air­borne vocal com­mu­ni­ca­tion in the Cal­i­for­nia sea lion, Za­lo­phus cal­i­for­ni­anus. An­i­mal Be­hav­ior, 17: 17-24.