Continued population recovery by Australian fur seals

Abstract

Australian fur seals (Arctocephalus pusillus doriferus) are conspicuous, top-level predators in coastal waters of south-eastern Australia that were over-harvested during the 1800s and have had a delayed recovery. A previous species-wide estimate of live pups in 2002 recorded a near-doubling of annual pup production and a 5% annual growth rate since the 1980s. To determine if pup production increased after 2002, we estimated live pup numbers in 2007. Pups were recorded at 20 locations: 10 previously known colonies, three newly recognised colonies and seven haul-out sites where pups are occasionally born. Two colonies adjacent to the Victorian coast accounted for 51% of live pups estimated: Seal Rocks (5660 pups, 25.9%) and Lady Julia Percy Island (5574 pups, 25.5%). Although some colonies were up and some were down in pup numbers, the 2007 total of 21 882 +/- 187 (s.e.) live pups did not differ significantly from a recalculated estimate of 21 545 +/- 184 in 2002, suggesting little change to overall population size. However, the colonisation of three new sites between 2002 and 2007 indicates population recovery has continued.

Full text

Continued population recovery by Australian fur seals
Roger Kirkwood
A
,
F
,David Pemberton
B
,Rosemary Gales
B
,Andrew J. Hoskins
C
,
Tony Mitchell
D
,Peter D. Shaughnessy
E
and John P. Y. Arnould
C
A
Research Department, Phillip Island Nature Parks, PO Box 97, Cowes, Vic. 3922, Australia.
B
Department of Primary Industries, Parks, Water and Environment, GPO Box 44,
Hobart, Tas. 7001, Australia.
C
School of Life and Environmental Sciences, Deakin University, Burwood, Vic. 3125, Australia.
D
Department of Sustainability and the Environment, 171 Nicholson St, Orbost,
Vic. 3888, Australia.
E
South Australian Museum, North Terrace, Adelaide, SA 5000, Australia.
F
Corresponding author. Email: rkirkwood@penguins.org.au
Abstract. Australian fur seals (Arctocephalus pusillus doriferus) are conspicuous, top-level predators in coastal waters
of south-eastern Australia that were over-harvested during the 1800s and have had a delayed recovery. A previous species-
wide estimate of live pups in 2002 recorded a near-doubling of annual pup production and a 5% annual growth rate since
the 1980s. To determine if pup production increased after 2002, we estimated live pup numbers in 2007. Pups were
recorded at 20 locations: 10 previously known colonies, three newly recognised colonies and seven haul-out sites where
pups are occasionally born. Two colonies adjacent to the Victorian coast accounted for 51% of live pups estimated: Seal
Rocks (5660 pups, 25.9%) and Lady Julia Percy Island (5574 pups, 25.5%). Although some colonies were up and some
were down in pup numbers, the 2007 total of 21 882 187 (s.e.) live pups did not differ significantly from a recalculated
estimate of 21 545 184 in 2002, suggesting little change to overall population size. However, the colonisation of three
new sites between 2002 and 2007 indicates population recovery has continued.
Additional keywords: Arctocephalus pusillus, population status, pups born.
Introduction
Southern hemisphere fur seals (genus Arctocephalus) have been
recovering after their over-exploitation by sealing operations in
the 1700s to 1900s (Reidman 1990). Many commercial fisheries
developed during the period of low seal numbers, and the
recovering seal populations often have been seen as competitors
for diminishing resources (David and Wickens 2003). The
timing and rates of recovery vary between species, as they are
dependent on the productivity of local foraging environments,
further human interactions and intrinsic factors (such as
fecundity); as a result, it is difficult to predict when populations
might reach maturity, and what sizes they might attain (Roux
1987; Wickens and York 1997; Arnould et al. 2003).
Australian fur seals (Arctocephalus pusillus doriferus)are
conspicuous, large-bodied predators in south-eastern Australian
waters and are known to interact with commercial and recreational
fisheries (Shaughnessy et al. 2003; Hamer and Goldsworthy 2006;
Robinson et al. 2008). They breed mainly on small islands in Bass
Strait and forage almost exclusively over shelf waters of south-
eastern Australia, making them one of the most geographically
restricted fur seal species (Warneke 1982; Pemberton and
Kirkwood 1994; Kirkwood et al. 2005). Recent genetic studies
reveal there is little inter-colony structure for Australian fur seals,
and the species can be considered a single population (Lancaster
et al. 2010). Gene flow between colonies is facilitated by both
sexes, with evidence that cows can pup at different colonies in
consecutive years (Lancaster et al. 2010).
Recovery of the Australian fur seal population from com-
mercial sealing has been slow relative to that of other fur seal
populations (Arnould et al. 2003). It has been estimated that,
prior to the late 1700s, up to 50 000 pups were produced
annually in Bass Strait (Warneke and Shaughnessy 1985). Ling
(1999) estimated that between 1798 and 1840, over 244 000
fur seal skins were exported from Bass Strait. Mostly, these
were Australian fur seals although New Zealand fur seals
(Arctocephalus forsteri) were also present (Kirkwood et al.
2009). Hunting to supply local markets continued until ,1923
(Warneke and Shaughnessy 1985). Coastal and offshore fish-
eries developed in south-eastern Australia in the early 1900s
(Tilzey and Rowling 2001) and saw the Australian fur seal as a
competitor, resulting in the shooting of seals around vessels
and on land, and the instigation of several culls (Warneke and
Shaughnessy 1985; Ling 1999). In 1975, all seals in Australian
waters became protected under the National Parks and Wildlife
Conservation Act in Commonwealth waters and under various
State legislation in State waters (Shaughnessy 1999).
CSIRO PUBLISHING
www.publish.csiro.au/journals/mfr Marine and Freshwater Research, 2010, 61, 695–701
ÓCSIRO 2010 10.1071/MF09213 1323-1650/10/060695

Annual pup production provides an indication of the size and
condition of a seal population (Berkson and DeMaster 1985).
Aerial photography of Australian fur seal pupping sites in 1945,
1975 and 1986 all resulted in total estimates of o10 000 pups
(Pearse 1979; Warneke and Shaughnessy 1985; Warneke 1988).
During the 1990s, it became evident that several colonies were
growing (Pemberton and Kirkwood 1994; Shaughnessy et al.
2002; Pemberton and Gales 2004) and a species-wide assess-
ment in 2002 suggested pup production had doubled since 1986,
exhibiting a 5% annual growth rate (Kirkwood et al. 2005). To
confirm this increase and investigate if it continued past 2002,
we estimated numbers of live pups at all sites following pupping
in November–December 2007.
Materials and methods
Estimation techniques
Visits to all known Australian fur seal colonies and haul-out sites
where pup births occur were conducted between late December
2007 and late February 2008 (Fig. 1, Table 1), after pup births
are complete, and before pups freely take to the water and
move between colony areas (Pemberton and Kirkwood 1994;
Shaughnessy et al. 1995b). Colonies were defined as having at
least 15 pups present, whereas haul-outs were sites with more
than 15 pups. This distinction reflects stages in colony estab-
lishment from being composed only of males and juveniles, to
having adult females present, to occasional births occurring, and
then a sufficient number of births (,15, Kirkwood, R., Gales, R.,
Shaughnessy, P. and Arnould, J., pers. obs.) for some pups to
survive to weaning. Estimation techniques mirrored those applied
at each site in 2002–03 (Kirkwood et al.2005).Listedinorderof
perceived increasing accuracy and increasing disruption to seals,
the techniques applied were aerial photography, direct ground
counts and capture–mark-resights (CMR).
We adopted aerial photography at Reid Rocks because
ground visits to these islets can be detrimental to small pups
(Pemberton and Kirkwood 1994). There are few access points
from the water for the seals, so small pups entering the water
can have difficulty getting out and may drown. The accuracy of
aerial estimates at Reid Rocks is optimised as pups have
minimal cover and therefore are easily viewed from the air.
Using a Cessna 172 aircraft at an altitude of 800 ft (250 m), we
took large-format digital photographs of the entire surface of
Reid Rocks with a hand-held SLR Camera that had a lens fitted
with an image stabiliser. The ISO range was set at 400 to 800
and a minimum shutter speed of 1/1250th of a second was
adopted. Four separate counts were made of pups identified in a
set of downloaded images that were enhanced in the program
Adobe Photoshop (CS2 version 9). An island-specific multiplier
(Mu ¼1.56, variance: V
Mu
¼0.0018) has been determined for
Reid Rocks to predict numbers that might be counted in a ground
census (G) from numbers counted in aerial photographs (A)
(Kirkwood et al. 2005). The variance of the ground estimate
(V
G
) and its standard error are:
VG¼VAðMuÞ2þVMu ðAÞ2
SEG¼½ðVGÞ=ðq1Þ0:5
where q is the number of counts (Cressie and Shaughnessy
1987).
Lady Julia Percy Is Seal Rocks
Kanowna Is
West Moncoeur Is
Rag Is
The Skerries
Judgement Rocks
Wright Rocks
Double Is
Reid Rocks Moriarty Rocks
Tenth Is
Bull Rock
Cape Bridgewater
Gabo Is
Montague Is
Wendar Is
Walker Is Maatsuyker Is
North Casuarina Is
200m
200 400 km
Colony
Haul-out
Bass Strait
Tasmania
Victoria
N.S.W.
South
Aust.
140°E145°E150°E
40°S
42°S
38°S
Fig. 1. Australian fur seal breeding colonies (filled circles) and haul-out sites (empty circles) where pups were born in 2007.
696 Marine and Freshwater Research R. Kirkwood et al.

Direct ground counts were conducted at West Moncoeur,
Moriarty Rocks, Wright Rock, Double Rock, Black Rock at Seal
Rocks, west coast and islets at Kanowna Island, and Delta Reef,
South Cave and Cave Shelf at Lady Julia Percy Island. For direct
counts, at least two observers searched a definable area of the
colony and recorded the number of pups seen. Counts were
repeated by each observer enabling the calculation of a mean
and standard error.
A CMR technique using a modified Petersen formula (Seber
1982; Shaughnessy et al. 2000; Shaughnessy et al. 2002) was
adopted at Tenth Island, Judgement Rocks, The Skerries, and
most of Seal Rocks, Kanowna Island and Lady Julia Percy
Island. CMRs account for the obscured portions of the pup
population that are not quantified by counts from aerial photo-
graphs or direct counts.
In CMR estimates, pups were caught and had a patch of black
natal-fur trimmed from the top of the head. This trim revealed a
distinctive, light-brown under-fur which remained visible until
early March, when pups moult into a silver-grey pelage. At all
sites, pups were marked by a team of three or more people who
moved through a breeding area catching pups that were readily
available. A recorder kept track of the numbers marked and
directed the team’s progress with the aim of spreading effort
evenly across a breeding area. We tried to mark more than 25%
of pups present, which is considered to be sufficiently large to
minimise bias and maximise accuracy (Caughley 1980).
We conducted resights while either overlooking or walking
through breeding areas. Overlooking the habitat was preferred
as it minimised disturbance but was not feasible where there
was no suitable vantage point or where a large and unknown
proportion of the pup population was hidden when viewed from
above. Resights were performed by two people; the ‘resighter’
scanned the heads of all pups visible and informed the ‘recorder’
if pups seen were marked or unmarked. Only pups that could
be clearly identified as marked or unmarked were included in
the resight samples. Schedules for resights varied between
locations, depending on the time available and the priorities of
researchers. Generally, we aimed to conduct six resights in all
areas, with the first resight performed at least 24 h after marking.
Previous studies have demonstrated that this period ensures
thorough mixing of marked and unmarked pups (Shaughnessy
et al. 1995b; Kirkwood et al. 2005).
After marking, individuals that leave a population through
movement or death were not available for resights and so must
be accounted for to avoid biases. Movement issues were mini-
mised by selecting geographic boundaries between breeding
areas that are seldom crossed by small pups, and by conducting
CMRs at a time of year when pups were small and tended to
remain within their natal area. Pup mortality was accounted for,
where possible, by individually scoring newly dead pups during
each resight. In large breeding areas, it became difficult to
keep track of which dead pups had been recorded on previous
resights. In these cases, we scored just the marked pups that
died, and estimated unmarked pup deaths based on these and the
ratio of marked to unmarked pups (Seber 1982). Arithmetic
means and variances about the means of all estimates were
calculated following White and Garrott (1990), as previously
described in Kirkwood et al. (2005). As each estimate of pup
numbers utilised all individuals in the population rather than a
sub-set of individuals, the square root of each variance provides
a standard error rather than a standard deviation (Chapman
1952; Fowler et al. 1998). Because each breeding area was
distinct unit while estimates were taking place, we estimated the
number of pups at a colony by summing the means for each
breeding areas, and the variance of the total by summing the
variances at each breeding area.
To estimate pup numbers for the taxon, we summed the
estimates from all sites, with combined figures from the three
techniques. The variances of these should not be summed,
though, because variance values from CMR methods indicate
variation on single estimates of all pups, whereas those from the
counts indicate variation in the ability to count the pups. To
ignore the variance values from counts, however, would result in
gross under-estimates of the confidence limits on the total.
Consequently, in the absence of more appropriate data, we have
combined all the variances in the estimate for the taxon.
Comparison with 2002 pup estimates
The species-wide estimate of live pup numbers for 2007 was
compared with the 2002 estimate using ‘Z’ tests (Seber 1982).
At Kanowna Island in 2002, pup numbers were estimated using
direct counts (Kirkwood et al. 2005) and we applied CMRs
in 2007. Recently, direct counts at this island were found to
underestimate pup numbers and a colony-specific multiplier
of 1.75 0.02 was calculated to approximate CMR estimates
(Gibbens and Arnould 2009b). We adjusted the 2002 estimate
at this site accordingly. The exponential rate of change (r) and
associated standard errors between counts ‘t’ years apart was
calculated (Caughley 1980) and expressed as percentages.
Table 1. Australian fur seal pupping sites and dates of estimates of live
pup numbers in 2007]08
Sites Latitude Longitude Date Status
Victoria
Lady Julia Percy Is 388420S 1428000E 6–11 Jan Colony
Seal Rocks 388300S 1458100E 26–31 Dec Colony
Kanowna Is 398100S 1468180E 23–25 Jan Colony
The Skerries 378450S 1498310E 15–18 Jan Colony
Rag Is 388580S 1468420E 11 Feb Colony
Cape Bridgewater 388230S 1418240E 20 Jan Haul-out
Gabo Is 378570S 1498920E 18 Jan Haul-out
Tasmania
Reid Rocks 408100S 1438550E 25 Feb Colony
West Moncoeur Is 398140S 1468300E 12 Jan Colony
Judgement Rocks 398300S 1478080E 9–10 Jan Colony
Tenth Is 408570S 1468590E 27 Dec–4 Jan Colony
Moriarty Rocks 408350S 1488160E 15 Jan Colony
Wright Rocks 398360S 1478320E 8 Jan New colony
Double Rocks 408200S 1478550E 8 Jan New colony
Bull Rock 408440S 1458180E 5 Jan Haul-out
Maatsuyker Is 438390S 1468170E 6–8 Mar Haul-out
Walker Is 438380S 1468170E 6–8 Mar Haul-out
Wendar Is 438250S 1458560E 6–8 Mar Haul-out
New South Wales
Montague Is 368150S 1508140E 5 Jan Haul-out
South Australia
North Casuarina Is 368400S 1368420E 31 Jan–1 Feb New colony
Australian fur seal pups Marine and Freshwater Research 697

Estimating total pups born and population size
Estimates of population size of fur seals have been derived from
pup production estimates in combination with multipliers
developed using demographic parameters such as pregnancy
and age-specific survival rates (Harwood and Prime 1978).
Estimating numbers of pups born from live pup estimates
requires knowledge of mortalities before colony visits. Such
data were unobtainable in this study as sites were visited only
once, and this occurred 1–2 months after pupping ceased. To
develop a rough estimate of pups born, we incorporated an over-
arching rate of 15% mortality before visits. The rate comes from
a study at Seal Rocks between 1966 and 1972, when 13 to 15%
of pups born in November–December each year had died by
early January (Warneke 1975). Perhaps coincidently, 15%
mortality was recorded for the November to early January period
at Tenth Island in 1991 (Pemberton and Kirkwood 1994). The
15% rate is incorporated cautiously, as mortality rates do vary
between site and year (Pemberton and Gales 2004; Gibbens and
Arnould 2009b). For example, large storms can cause losses of
greater than 50% at low-lying colonies in some years (Pemberton
and Gales 2004). As pup mortalities might have ranged broadly
from the 15% rate, we rounded estimates of pups born to two
significant numbers and did not calculate variances.
A multiplier of 4.5 pup production was applied to estimate
total seal numbers, including pups, associated with each site
(Gibbens and Arnould 2009a). No estimates of variance were
available for this multiplier and, in line with the estimates of pups
born, we rounded figures to two places and did not calculate
variances.
Results and discussion
In 2007, Australian fur seal pups were recorded at 20 locations:
10 previously known colonies, 3 new colonies and 7 haul-out
sites where pups are occasionally born (Tables 1, 2). Two
colonies adjacent to the Victorian coast accounted for 51% of
live pups estimated: Seal Rocks (25.9%) and Lady Julia Percy
Island (25.5%). Three colonies (two Victorian and one in
Tasmanian Bass Strait) produced an additional 37% of pups:
Kanowna Island (13.3%), The Skerries (12.4%) and Judgement
Rocks (10.9%). The three newly recognised colonies were
Wright Rocks (n¼130 pups) and Double Rocks (n¼51) in
Tasmanian Bass Strait; and North Casuarina Island (n¼28),
near Kangaroo Island, South Australia. Assuming a 15% mor-
tality of pups before the census dates, ,26 000 Australian fur
seal pups were born in 2007. Using the 4.5 multiplier (Gibbens
and Arnould 2009a) provides a total population estimate of
,120 000 seals (Table 2).
In 2002, a total of 19 819 163 live pups was estimated for
the species (Kirkwood et al. 2005). To compare the 2002 and
2007 estimates, techniques applied should be comparable. At
Kanowna Island, however, a direct count was used in 2002 and a
CMR in 2007. Using the site-specific multiplier of 1.75 to derive a
CMR estimate from a direct count (Gibbens and Arnould 2009b),
the 2002 ground count of 2301 21 live pups equates with a
CMR estimate of 4026 127. This revises the 2002 estimate to
21 545 184 live pups. Assuming 15% mortality prior to counts
and the 4.5 multiplier (previously 3.95 was applied; Goldsworthy
et al. 2003) derives a revised total population estimate for 2002
of ,110 000 seals. This is comparable to the 2007 estimate given
the rounding of data to two significant figures.
The total live pups estimated for 2007 (21 882 187,
Table 2) suggested a growth rate of 0.31 0.21% per year since
2002, although estimates for the years did not differ significantly
(Z¼1.49, P¼0.07). Previously, between 1986 and 2002, an
annual rate of increase of up to 5% was estimated (Kirkwood
et al. 2005), although the 1986 estimate was based on adjusted
aerial counts, and probably underestimated pup production at
some sites (Warneke 1988). However, the 5% rate of increase
accords with rates recorded at several individual colonies during
the 1990s (Shaughnessy et al. 2000; Kirkwood et al. 2005).
Thus, although pup production by Australian fur seals did not
increase significantly between 2002 and 2007, expansion was
evident in the colonisation of new sites. After confinement to
nine colonies for over 100 years (before ,2000), there are now
13 established colonies of Australian fur seals, suggesting the
species’ vulnerability is reducing.
Interannual variation in pup numbers is evident at Australian
fur seal colonies, with patterns of variation not correlating across
sites (Fig. 2; Pemberton and Kirkwood 1994; Pemberton and
Gales 2004; Gibbens and Arnould 2009b). Several factors might
be contributing to this variation. For example, vulnerability
to high seas and wave action is colony-specific. Reid Rocks,
Tenth Island and Moriarty Rocks, which displayed great
changes between years, are low-lying rocks, and small pups
on them are susceptible to being washed away. Diseases such as
septicaemia can also influence pup survival, and appear to be
highest where access to clean pools is limited (Pemberton and
Gales 2004). In addition, changes in currents influencing the
unique water bodies around pupping sites can influence foraging
conditions for cows, and thus pup production and survival. For
instance, sea surface temperature fluctuations correlate with
changes in diet, time of pupping and pup production at sites
in northern Bass Strait (Kirkwood et al. 2008; Gibbens and
Arnould 2009b). As a consequence of these colony-specific
annual variations in pup production, estimates from a single year
should be interpreted cautiously.
Since at least the 1980s, pup production by Australian fur
seals has been concentrated in northern Bass Strait. Islands
within 10 km of the Victorian coastline contained 61% of the
species’ total pup production in 1986, 79% in 2002 and 78% in
2007. In 2002, the establishment of a new breeding colony, at
Rag Island, Victoria, was the first to be recorded since at least
the 1920s, and highlight the importance of the Victorian coast
to Australian fur seals (Kirkwood et al. 2005). The most
substantial change to the breeding distribution recorded in
the present survey was the newly recognised colony at North
Casuarina Island, South Australia. This represents the first
westward movement of the species out of the vicinity of Bass
Strait. South Australian waters are more productive than are
the waters of Bass Strait (Middleton et al. 2007; Middleton and
Bye 2007); large colonies of New Zealand fur seals already
occur there (Shaughnessy et al. 1994; Shaughnessy et al.
1995a; Shaughnessy and McKeown 2002) and it is the primary
breeding region for the endangered Australian sea lion,
Neophoca cinerea (Gales et al. 1994; Goldsworthy and Page
2007). Both these species forage over the continental shelf
(Fowler et al. 2007; Baylis et al. 2008) and might compete for
698 Marine and Freshwater Research R. Kirkwood et al.

Table 2. Estimates of live pup numbers of Australian fur seals following pupping in 2007, and derived estimates of pups born and total seal numbers
Includes method (capture–mark-resight (CMR), direct ground counts or aerial photography), pups marked, percentage of pups in resights. Estimates of pups
born in 2007 assume 15% mortality before counts (Warneke 1975; Pemberton and Kirkwood 1994), and total seal numbers use a species-specific multiplierof
4.5 numbers of pups born (Gibbens and Arnould 2009a). Live pup data are rounded to integers and derived data to two significant figures, so totals need not
conform to numbers in the columns
Sites Method Pups marked (%) % pups in resights (s.e.) Live pups (s.e.) Pups born Total seals
Seal Rocks
SR North Bay CMR 482 (42) 49 (1) 1150 (17)
SR West Bay CMR 502 (47) 40 (2) 1077 (18)
SR Main Beach CMR 1178 (51) 32 (2) 2342 (29)
Back of Main Count – – 97
A
Black Rock Count – – 993 (74)
Subtotal 2162 5660 (83) 6700 30 000
Lady Julia Percy Is
Cape Frederick CMR 242 (44) 64 (2) 549 (8)
Dinghy Cove CMR 534 (39) 53 (2) 1368 (18)
Landslip Point CMR 398 (50) 56 (3) 798 (11)
Sphinx Head CMR 457 (46) 63 (3) 1002 (11)
Square Reef CMR 209 (43) 64 (2) 498 (9)
Seal Bay CMR 551 (55) 32 (2) 1012 (17)
Delta Reef Count – – 154
A
South Cave Count – – 186
A
Cave Shelf Count – – 7
AB
Subtotal 2391 5574 (73) 6600 30 000
Kanowna Is
East Coast CMR 300 (37) 18 (1) 837 (23)
West Coast CMR 32 (11) 15 289 (103)
North Slopes CMR 451 (25) 19 (1) 1695 (33)
Blowhole Slope Count – – 84 (2)
Islets Count – – 8
A
Subtotal 751 2913 (110) 3400 15000
The Skerries
Inner Islet CMR 101 (37) 39 (3) 237 (9)
Middle Islet CMR 510 (34) 35 (1) 1545 (24)
Outer Islet CMR 290 (40) 39 (5) 923 (17)
Subtotal 901 2705 (31) 3200 14 000
Rag Island Count – – 277
A
330 1500
Cape Bridgewater Count – – 7
A
837
Gabo Island Count – – 1
A
15
Judgement Rocks CMR 500 (21) 16 (2) 2387 (75) 2800 13 000
Reid Rocks Aerial
C
– – 886 (52) 1000 4700
Moriarty Rocks Count – – 598 (9) 700 3200
Tenth Island Count – – 448 (20) 530 1800
West Moncoeur Island Count – – 204 (6) 240 1100
Wright Rocks Count – – 130 (1) 150 690
Double Rocks Count – – 51
A
60 270
Bull Rock Count – – 7
A
837
Maatsuyker Island Count – – 1
A
211
Walker Island Count – – 1
A
15
Wender Island Count – – 1
A
15
Montague Island Count – – 2
A
211
Nth Casuarina Island
D
CMR – – 28 33 150
Total 21 882 26 000 120 000
A
Single, direct counts.
B
Cave Shelf was viewed from above only so the count represents a minimum. During a thorough search of the shelf and all its caves in Jan. 2009, 50 pups were
recorded.
C
The aerial count at Reid Rocks (567 pups) has been adjusted using a site specific multiplier (1.56).
D
North Casuarina estimate comprised 27 pups from CMR plus one pup that was marked incorrectly as a New Zealand fur seal.
Australian fur seal pups Marine and Freshwater Research 699

resources with the Australian fur seal. There is, however, a
great potential for growth in Australian fur seal numbers in
regions of high productivity in South Australia.
Future population sizes and distribution of Australian fur
seals can potentially also be influenced by current global sea-
warming, which could force temperate marine communities
towards higher latitudes (Poloczanska et al. 2007). If this occurs
in southern Australia, the breeding range of the Australian fur
seals might expand into southern Tasmanian waters, where
substantial haul-out sites exist and pups are occasionally born,
such as at Maatsuyker Island, Walker Island, Wender Island and
Isle des Phoques.
Acknowledgements
For assistance in the field, we thank all the boat drivers and field workers,
including Richard Hill and Joe Austin for counts at Cape Bridgewater, and
Darryl Stafford of Stanley Seal Cruises for counts at Bull Rock. We also
thank the journal editor and two anonymous referees whose comments and
suggestions greatly enhanced the final presentation. Research was con-
ducted under animal ethics permits 2.2007 from the Phillip Island Nature
Park AEEC, A34/2004 from Deakin University AWC and 16/2006–07 from
Tasmanian DPIPWE AEC, and Wildlife Research Permits 10004150 and
10003856 from the Victorian Department of Sustainability and Environment
and scientific permits issued by DPIWE. The project was co-funded by the
Australian Marine Mammal Centre, Phillip Island Nature Parks, the Princess
Melikoff Marine Mammal Conservation Trust, and the Australian Research
Council.
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0
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1985 1990 1995 2000 2005 2010
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Lady Julia Percy Is
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Tenth Is
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Pups Pups
CMR(a)
West Moncoeur
Moriarty Rocks
Reid Rocks
(b) Counts
Fig. 2. Comparison of 2007 live pup numbers estimated at Australian fur
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Manuscript received 28 August 2009, accepted 14 December 2009
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