Summer diving behaviour of lactating New Zealand sea lions, Phocarctos hookeri

1997 ◽  
Vol 75 (10) ◽  
pp. 1695-1706 ◽  
Author(s):  
N. J. Gales ◽  
R. H. Mattlin
Keyword(s):  
New Zealand ◽  
Dive Depth ◽  
Diving Behaviour ◽  
Physiological Adaptation ◽  
Sea Lions ◽  
Dive Behaviour ◽  
Physiological Limits ◽  
Aerobic Dive Limit ◽  
Foraging Environment ◽  
Phocarctos Hookeri

The diving behaviour of 14 female New Zealand sea lions (Phocarctos hookeri) was recorded during early lactation in January and February 1995 on the Auckland Islands, New Zealand. During 73 trips to sea, 19 720 dives were recorded. The average duration of a foraging cycle was 2.9 days (range 1.4–4.8 days), of which 1.7 days (57%) (range 1.1–3.4 days) were spent at sea and 1.2 days (43%) (range 0.8–2.3 days) ashore. At sea the sea lions dived almost continuously at a rate of 7.5 dives/h and spent a mean of 45% of the time submerged (≥ 2 m). Dive behaviour varied among individuals but showed no diel pattern overall. The dive depth for all dives ≥ 6 m was 123 ± 87 m (mean ± SD) (median 124 m, maximum 474 m) and ranged among individuals from 79 ± 85 to 187 ± 166 m. About half of the dives were in the 101- to 180-m range. The duration of all dives was 3.9 ± 1.8 min (median 4.33 min, maximum 11.3 min); about half (51%) of the dive durations were between 4 and 6 min. Surface interval was 4.5 ± 15.8 min (median 1.9 min). Almost half (44%) of all dives exceeded the calculated aerobic dive limit of each sea lion (range 16–73% for individuals). Most dive profiles were flat bottomed and, we believe, are to the benthos. A mean of 51.5% of all dive time was spent in the deepest 85% of the dive. Prey remains found during this study were primarily of benthic and demersal organisms. Phocarctos hookeri is the deepest and longest diving of any of the otariids recorded to date. We suggest that the dive behaviour may reflect either successful physiological adaptation to exploiting benthic prey and (or) a marginal foraging environment in which diving behaviour is close to physiological limits.

In the shallow end: diving behaviour of recolonising female New Zealand sea lions (Phocarctos hookeri) around the Otago Peninsula

2011 ◽  
Vol 89 (12) ◽  
pp. 1195-1205 ◽  
Author(s):  
Amélie A. Augé ◽  
B. Louise Chilvers ◽  
Lloyd S. Davis ◽  
Antoni B. Moore
Keyword(s):  
New Zealand ◽  
Dive Depth ◽  
Dive Duration ◽  
Diving Behaviour ◽  
Marine Habitat ◽  
Sea Lions ◽  
The Core ◽  
The Mean ◽  
Historical Range ◽  
Phocarctos Hookeri

Female New Zealand sea lions ( Phocarctos hookeri (Gray, 1844)) at the Auckland Islands (remnant populations) are the deepest and longest diving otariids. These remnant populations are found at the margin of the historical range of the species. We hypothesized that diving behaviours of animals in the core of their historical range is less extreme owing to a better marine habitat. All female New Zealand sea lions (n = 13, aged 2–14 years) born on the Otago Peninsula (initial recolonising population) were equipped with time–depth recorders during April and May 2008, 2009, and 2010. The mean dive depth was 20.2 ± 24.5 m and mean dive duration was 1.8 ± 1.1 min, some of the lowest values reported for otariids. Otago female New Zealand sea lions did not exhibit two distinct diving specialisations as reported at the Auckland Islands. Otago adult females exceeded calculated aerobic dive limits in 7.1% of dives compared with 68.7% at the Auckland Islands. The contrasting differences in diving behaviour between Otago and the Auckland Islands suggest that Otago represents a better marine habitat for New Zealand sea lions, with food easily accessible to animals of all ages.

Foraging energetics and diving behavior of lactating New Zealand sea lions, Phocarctos hookeri

2000 ◽  
Vol 203 (23) ◽  
pp. 3655-3665 ◽  
Author(s):  
D.P. Costa ◽  
N.J. Gales
Keyword(s):  
New Zealand ◽  
Metabolic Rate ◽  
Dive Depth ◽  
Diving Behavior ◽  
Metabolic Rates ◽  
Sea Lion ◽  
Water Turnover ◽  
Sea Lions ◽  
The Mean ◽  
Phocarctos Hookeri

The New Zealand sea lion, Phocarctos hookeri, is the deepest- and longest-diving sea lion. We were interested in whether the diving ability of this animal was related to changes in its at-sea and diving metabolic rates. We measured the metabolic rate, water turnover and diving behavior of 12 lactating New Zealand sea lions at Sandy Bay, Enderby Island, Auckland Islands Group, New Zealand (50 degrees 30′S, 166 degrees 17′E), during January and February 1997 when their pups were between 1 and 2 months old. Metabolic rate (rate of CO(2) production) and water turnover were measured using the (18)O doubly-labeled water technique, and diving behavior was measured with time/depth recorders (TDRs). Mean total body water was 66.0+/−1.1 % (mean +/− s.d.) and mean rate of CO(2) production was 0. 835+/−0.114 ml g(−)(1)h(−)(1), which provides an estimated mass-specific field metabolic rate (FMR) of 5.47+/−0.75 W kg(−)(1). After correction for time on shore, the at-sea FMR was estimated to be 6.65+/−1.09 W kg(−)(1), a value 5.8 times the predicted standard metabolic rate of a terrestrial animal of equal size. The mean maximum dive depth was 353+/−164 m, with a mean diving depth of 124+/−36 m. The mean maximum dive duration was 8.3+/−1.7 min, with an average duration of 3.4+/−0.6 min. The deepest, 550 m, and longest, 11.5 min, dives were made by the largest animal (155 kg). Our results indicate that the deep and long-duration diving ability of New Zealand sea lions is not due to a decreased diving metabolic rate. Individual sea lions that performed deeper dives had lower FMRs, which may result from the use of energetically efficient burst-and-glide locomotion. There are differences in the foraging patterns of deep and shallow divers that may reflect differences in surface swimming, time spent on the surface and/or diet. Our data indicate that, although New Zealand sea lions have increased their O(2) storage capacity, they do not, or cannot, significantly reduce their at-sea metabolic rates and are therefore likely to be operating near their physiological maximum.

Diving behaviour of lactating southern sea lions (Otaria flavescens) in Patagonia

1995 ◽  
Vol 73 (11) ◽  
pp. 1975-1982 ◽  
Author(s):  
Rodolfo Werner ◽  
Claudio Campagna
Keyword(s):  
Median Duration ◽  
Dive Depth ◽  
Dive Duration ◽  
Diving Behaviour ◽  
Diel Variation ◽  
Otaria Flavescens ◽  
Sea Lions ◽  
Aerobic Dive Limit

The diving behaviour of six lactating female southern sea lions (Otaria flavescens) was recorded during 52.4 animal-days at sea. Information was obtained from 18 057 dives. Females spent 52.7 ± 6.2% of the time at sea diving. Median and maximum dive depths ranged from 19 to 62 and from 97 to 175 m, respectively. Dives were short, with median and maximum durations ranging from 2.1 to 3.2 and from 4.4 to 7.7 min, respectively. Dives deeper than 10 m represented 56 – 89% of total dives and involved 93 – 97% of total diving time. Mean dive depth and duration of dives greater than 10 m were 61 m and 3 min, respectively. Most of these dives (69%) had a flat-bottomed U-shaped profile, bottom time constituting about half of the dive duration. Shallow dives, with a modal depth of 2 m, were short (median duration 0.1 –0.8 min), with virtually no time spent at the bottom of the dive. During trips to sea, which ranged from less than 1 day to more than 4 days, females dove continuously. Mean dive frequency was between 11 and 19 per hour. Surface intervals were short (median 0.9–1.2 min) and there was no apparent diel variation in dive depth or frequency. The estimated aerobic dive limit of the females was exceeded on only a few dives (0.7 – 6.2%). Transit to potential foraging areas took 0.2–8.3 h.

Size and experience matter: diving behaviour of juvenile New Zealand sea lions (Phocarctos hookeri)

Polar Biology ◽  
2013 ◽  
Vol 37 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Elaine S. Leung ◽  
B. Louise Chilvers ◽  
Shinichi Nakagawa ◽  
Bruce C. Robertson
Keyword(s):  
New Zealand ◽  
Diving Behaviour ◽  
Sea Lions ◽  
Phocarctos Hookeri

scholarly journals NEONATAL MORTALITY IN NEW ZEALAND SEA LIONS (PHOCARCTOS HOOKERI ) AT SANDY BAY, ENDERBY ISLAND, AUCKLAND ISLANDS FROM 1998 TO 2005

2007 ◽  
Vol 43 (3) ◽  
pp. 461-474 ◽  
Author(s):  
A. Castinel ◽  
P. J. Duignan ◽  
W. E. Pomroy ◽  
N. López-Villalobos ◽  
N. J. Gibbs ◽  
...  
Keyword(s):  
New Zealand ◽  
Neonatal Mortality ◽  
Sea Lions ◽  
Phocarctos Hookeri

scholarly journals Pathology and Epidemiology of Stillbirth in New Zealand Sea Lions (Phocarctos hookeri) From Enderby Island, Auckland Islands, 1998–2012

2016 ◽  
Vol 53 (6) ◽  
pp. 1241-1247 ◽  
Author(s):  
S. A. Michael ◽  
B. L. Chilvers ◽  
S. A. Hunter ◽  
P. Duignan ◽  
W. Roe
Keyword(s):  
New Zealand ◽  
Sea Lions ◽  
Phocarctos Hookeri

Philopatry and site fidelity of New Zealand sea lions (Phocarctos hookeri)

2008 ◽  
Vol 35 (5) ◽  
pp. 463 ◽  
Author(s):  
B. Louise Chilvers ◽  
Ian S. Wilkinson
Keyword(s):  
New Zealand ◽  
Site Fidelity ◽  
Breeding Area ◽  
Quantitative Investigation ◽  
Sea Lion ◽  
Breeding Sites ◽  
Auckland Island ◽  
Sea Lions ◽  
Breeding Habitats ◽  
Phocarctos Hookeri

The New Zealand sea lion (NZ sea lion), Phocarctos hookeri, is New Zealand’s only endemic pinniped, and one of the worlds rarest otariids. It is classified as ‘Threatened’ based primarily on the low number of breeding sites and restricted distribution. In New Zealand, a species listed as ‘threatened’ is required to be managed to allow its recovery and removal from the list within 20 years. For NZ sea lions this is dependant on the establishment of new breeding areas. However, understanding the recolonisation processes for pinnipeds is still in its infancy with factors such as philopatry needing more research to understand individual dispersal and the recolonisation process. This paper presents the first quantitative investigation into the level of site fidelity and philopatry to breeding beaches in NZ sea lions. Data from resights of NZ sea lions marked as pups from the northern Auckland Island breeding area suggest that both site fidelity and philopatry are important characteristics of this species. Our results show that overall: (1) females have a higher resighting rate than males, particularly at natal sites; (2) female non-natal resightings are predominantly restricted to locations within the northern Auckland Island breeding area (an area of ~10 km2), whereas male resightings are more widely dispersed (up to 700 km to NZ mainland); and (3) philopatry occurs for both sexes, but is more predominant in females than males, with males displaying delay related to sexual and social maturity. The colonisation of new breeding habitats rarely occurs when philopatry is strong and population density is low, stable or declining such as seen for NZ sea lions. Therefore, this research indicates that management of NZ sea lions needs to minimise anthropogenic mortality and encourage population growth to maximise density at breeding sites and encourage females to disperse to establish new breeding areas.

scholarly journals Pup mortality in New Zealand sea lions (Phocarctos hookeri) at Enderby Island, Auckland Islands, 2013-18

PLoS ONE ◽  
2019 ◽  
Vol 14 (11) ◽  
pp. e0225461
Author(s):  
Sarah A. Michael ◽  
David T. S. Hayman ◽  
Rachael Gray ◽  
Ji Zhang ◽  
Lynn Rogers ◽  
...  
Keyword(s):  
New Zealand ◽  
Sea Lions ◽  
Pup Mortality ◽  
Phocarctos Hookeri

Seasonal dive behaviour of lactating New Zealand fur seals (Arctocephalus forsteri)

1998 ◽  
Vol 76 (2) ◽  
pp. 350-360 ◽  
Author(s):  
R H Mattlin ◽  
N J Gales ◽  
D P Costa
Keyword(s):  
New Zealand ◽  
Dive Depth ◽  
Dive Duration ◽  
Early Summer ◽  
Late Winter ◽  
Individual Values ◽  
Dive Behaviour ◽  
Fur Seals ◽  
Fur Seal ◽  
Bay Islands

The dive behaviour of 18 female New Zealand fur seals (Arctocephalus forsteri) from Taumaka, Open Bay Islands, New Zealand (43°52'S, 168°53'E), was recorded during early (summer; December-February), mid (autumn; March-May), and late (winter; June-August) lactation. Mean dive depth, dive duration, and bottom time for dives >=6 m in depth increased from summer through winter. Variation in individual seal dive behaviour within a season accounted for approximately 11, 9, and 11% of the observed difference between seasons in dive depth, dive duration, and bottom time, respectively. Seasonal dive data (mean ± 1 SD) were as follows: summer: dive depth 30 ± 37 m, dive duration 1.4 ± 1.1 min, and bottom time 0.5 ± 0.6 min; autumn: dive depth 54 ± 47 m, dive duration 2.4 ± 1.3 min, and bottom time 1.0 ± 0.8 min; winter: dive depth 74 ± 64 m, dive duration 2.9 ± 1.5 min, and bottom time 1.2 ± 1.1 min. Maximum recorded dive depth was 274 m for a 5.67-min dive in autumn. Maximum duration was 11.17 min for a dive to 237+ m in winter. New Zealand fur seals are the deepest diving fur seal species reported thus far. The estimated theoretical aerobic dive limit was exceeded on 18.4% of dives (range of individual values 0.2-57.8%). Females (n = 12) were ashore about 1.8 days at a time during February through November, and this increased to about 4.3 days during December and January. Average time spent away from the rookery ranged from 3 to 15 days.

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