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Large-scale tropical movements and diving behavior of white sharks Carcharodon carcharias tagged off New Zealand

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Recent advances in our understanding of the spatial behavior of white sharks have been based on only 3 geographical areas: the waters off Australia, southern Africa, and the northeast Pacific Ocean. Here we report results from the first study in New Zealand waters using satellite tags to study sharks. We attached pop-up archival tags to 4 white sharks Carcharodon carcharias at the Chatham Islands, New Zealand, during April 2005. One tag released prematurely, but 3 others showed long-distance northward movements of 1000 to 3000 km across the open ocean, with 2 sharks moving to the tropical islands of New Caledonia and Vanuatu. Our results are similar to recent findings elsewhere of fast oceanic travel and well oriented navigation. Circumstantial information suggests that some of these movements could be part of a regular foraging migration where white sharks visit humpback whale wintering grounds to feed on carcasses and prey on newborn calves. Before embarking on large-scale movements, all sharks remained over the continental shelf near the Chatham Islands for 2.6 to 5.0 mo, rarely swimming deeper than 100 m. In contrast, during oceanic large-scale movements, they spent most of their time in the top 1 m of water, showing periodic dives to depths over 900 m. The diving behavior in combination with the large-scale movements from temperate to tropical waters results in the sharks experiencing a very wide range of water temperatures.
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AQUATIC BIOLOGY
Aquat Biol
Vol. 8: 115–123, 2010
doi: 10.3354/ab00217 Published online January 12
INTRODUCTION
The white shark Carcharodon carcharias (also known
as the great white shark) is a globally distributed
apex predator, with reported centers of abundance in
temperate and sub-tropical waters (Compagno 2001).
Negative abundance trends and rapid population de-
clines reported in several range states have high-
lighted the need for improved knowledge of this
species (Malcolm et al. 2001, Soldo & Jardas 2002,
Anonymous 2004), and have led to its protection in a
number of countries as well as its inclusion on Appen-
dix II of the Convention for International Trade in
Endangered Species of Animals and Plants (CITES)
and Appendices I and II of the Convention on the Con-
servation of Migratory Species of Wild Animals (CMS).
As recently as 2001, the white shark was considered
to be chiefly an inhabitant of continental and insular
shelves, and its migratory habits were virtually
unknown (Compagno 2001). However, recent research
through satellite-linked tags has demonstrated that
besides spending extended periods of time in pre-
ferred coastal areas, white sharks commonly venture
thousands of kilometers into the open ocean (Boustany
et al. 2002) and undertake regular long-distance
coastal migrations, often returning to sites to which
they show a high degree of fidelity (Bonfil et al. 2005,
Bruce et al. 2006, Weng et al. 2007a,b). One white
© Inter-Research 2010 · www.int-res.com*Email: ramon.bonfil@gmail.com
Deceased
Large-scale tropical movements and diving
behavior of white sharks Carcharodon carcharias
tagged off New Zealand
R. Bonfil1,*, M. P. Francis2, C. Duffy3, M. J. Manning2,†, S. O’Brien4
12233 Caton Ave. 5C, Brooklyn, New York 11226, USA
2National Institute of Water and Atmospheric Research, 301 Evans Bay Parade, Greta Point, Wellington 6021, New Zealand
3Department of Conservation, Private Bag 68908, Newton, Auckland 1145, New Zealand
4School of Aquatic & Fishery Sciences, University of Washington, 1122 NE Boat St., Seattle, Washington 98105, USA
ABSTRACT: Recent advances in our understanding of the spatial behavior of white sharks have been
based on only 3 geographical areas: the waters off Australia, southern Africa, and the northeast
Pacific Ocean. Here we report results from the first study in New Zealand waters using satellite tags
to study sharks. We attached pop-up archival tags to 4 white sharks Carcharodon carcharias at the
Chatham Islands, New Zealand, during April 2005. One tag released prematurely, but 3 others
showed long-distance northward movements of 1000 to 3000 km across the open ocean, with 2 sharks
moving to the tropical islands of New Caledonia and Vanuatu. Our results are similar to recent find-
ings elsewhere of fast oceanic travel and well oriented navigation. Circumstantial information sug-
gests that some of these movements could be part of a regular foraging migration where white sharks
visit humpback whale wintering grounds to feed on carcasses and prey on newborn calves. Before
embarking on large-scale movements, all sharks remained over the continental shelf near the
Chatham Islands for 2.6 to 5.0 mo, rarely swimming deeper than 100 m. In contrast, during oceanic
large-scale movements, they spent most of their time in the top 1 m of water, showing periodic dives
to depths over 900 m. The diving behavior in combination with the large-scale movements from tem-
perate to tropical waters results in the sharks experiencing a very wide range of water temperatures.
KEY WORDS: Great white shark .Archival satellite tags .Southwest Pacific Ocean
Resale or republication not permitted without written consent of the publisher
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Aquat Biol 8: 115– 123, 2010
shark made an impressive and fast transoceanic return
migration, covering more than 22 000 km in less than
9 mo (Bonfil et al. 2005). White sharks also display dif-
ferent diving behaviors during oceanic versus shelf
residence, and Bonfil et al. (2005) and Weng et al.
(2007a) speculated that celestial clues are used during
oceanic navigation.
White sharks are common in New Zealand waters
and were recently protected within its Territorial Sea
and Exclusive Economic Zone, but in this part of their
range, there has been little research on their biology,
including movements. Here we present data on the
meso- and macro-scale movements and diving behav-
ior of 3 white sharks tagged with archival satellite tags
at the Chatham Islands, New Zealand.
MATERIALS AND METHODS
Satellite tagging. Four white sharks (3 females, 1
male) were tagged with pop-up archival transmitting
tags (PAT4 tags; Wildlife Computers) during April 2005
at Star Keys, Chatham Islands, New Zealand (175°
59.16’ W, 44° 13.40’S; Table 1). All sharks were tagged
free-swimming, following the procedure described in
Bonfil et al. (2005). Tagged sharks were sexed visually
from diving cages or from the surface as they passed
close to the boat. Shark size was estimated visually by
at least 2 experienced observers and ranged between
ca. 350 and 450 cm in total length (TL; Table 1). Tags
were deployed for 3 to 6 mo (Table 1) and programmed
to record depth, temperature, and light measurements
at 60 s intervals. Limits for depth bins are shown in
Fig. 4; upper limits for temperature bins were 4, 6, 8,
10, 12, 14, 16, 18, 20, 23, 26, and 60°C. Archival data
were transmitted to Argos satellites in 6 h bins (starting
at 00:00, 06:00, 12:00, and 18:00 h local time).
Data analysis. Daily shark positions were estimated
from ambient light-level data collected by PAT4 tags
using the geolocation algorithms implemented in
software available from www.wildlifecomputers.com
(WC-AMP 1.01.009, WC-GPE 1.01.0005). To reduce
the inherent uncertainty of these estimates (Musyl et
al. 2001, Itoh et al. 2003, Wilson et al. 2007), revised
‘most-probable’ daily positions were estimated by
Kalman filter analysis. The model assumed was the
Nielsen et al. (2006) extension of the model of Sibert et
al. (2003) incorporating sea-surface temperature (SST);
the ‘solstice’ error model was assumed in all fits.
The number of data points fitted to each track is
listed in Table 2. Days for which PAT-measured
SST data were implausible (observed SST above 35°C)
were omitted from the analysis. The deployment and
pop-up positions (Table 1) were assumed by the
Kalman filter fitting routine to be known without error.
Longitude and SST bias were not estimated, and lati-
tude bias was estimated in all fits. Composite SST field
data on a 1° longitude ×1° latitude grid for the dates
and area of interest and averaged over consecutive
8 d periods were downloaded from the online NMFS
atlas deposited at the University of Hawaii and used
in the model fits as described by Nielsen et al. (2006).
Most-probable position estimates and surrounding
confidence regions (within 2 SE) were extracted from
the fitted model object for each track.
Approximate departure dates from the Chatham
Islands were estimated by simultaneous examination
of temporal changes in longitude, depth, and tempera-
ture. Missing data prevented exact determination of
the departure dates, but errors were probably minimal
(~± 2 d). Oceanic travel swimming speeds were esti-
mated based on great circle distances traveled from
the Chatham Islands to the pop-up points and time
spent traveling.
For days with no PAT4 depth-temperature (PDT)
profile data in the transmitted data summaries, we con-
servatively estimated these values from the 6 h bin
data where they existed: minimum depths and temper-
116
Table 1. Carcharodon carcharias. Details of tag deployments on white sharks at the Star Keys, Chatham Islands, New Zealand. Speed
estimates are for oceanic traveling, and are not based on the entire deployment time period. Dates are in Universal Time. F: female;
M: male; Est. TL: estimated total length; n/a: not available
Tag no. Sex Est. TL (m) Tagging date Pop-up date Pop-up Argos pop-up Distance Deployment (d) Speed
(2005) (2005) location location class traveled (km) Programmed Actual (km h–1)
57033 F 4.2 to 4.5 7 Apr 5 Jul 172° 02.1’W 1 1036 89 89 5.4
35° 25.4’ S
57034 F 3.5 9 Apr 14 Apr 176°17.4’ W n/a n/a 120 5 n/a
43° 45.6’ S
57035 F 4.0 9 Apr 5 Sep 167° 09.3’E 1 2847 149 149 3.7
22° 45.3’ S
57036 M 3.2 to 3.5 8 Apr 5 Oct 169° 38.7’E 2 2884 180 181 4.3
21° 11.2’ S
Bonfil et al.: Tropical movements of NZ white sharks
atures were estimated as the upper (deeper, warmer)
bound of the lowest bin in each 24 h period, and maxi-
mum depths and temperatures were estimated as the
lower (shallower, cooler) bound of the highest bin in
each 24 h period. This procedure allowed approximate
temporal interpolation between daily PDT estimates
but at the expense of underestimating the maxima and
overestimating the minima.
RESULTS
We successfully tracked 3 sharks for periods of 89,
149, and 181 d (Table 1). Summary data transmitted for
each tag via the Argos system comprised time-at-depth
data, time-at-temperature data, depth-temperature pro-
file data, and geolocation estimates of longitude and
latitude based on light readings.
Geographic movements
A 3.8 to 4.0 m TL female white shark (Tag 57034,
programmed for a 4 mo deployment) prematurely shed
its tag 5 d after tagging. This tag reported to the Argos
system from ~70 km north of the tagging site, but the
tag may have drifted from elsewhere before transmit-
ting (it was programmed to detach and transmit after
168 h at a constant depth).
A second female white shark, 4.2 to 4.5 m TL (Tag
57033, a 3 mo deployment) traveled to the Louisville
Seamount Chain, 1036 km northeast of the Chatham
Islands (Table 1). The pop-up region has no shallow
water: most of the sea floor is at depths >4000 m,
although several seamounts within 55 to 90 km rise to
depths of 2400 to 3700 m. A third female white shark,
ca. 4.0 m TL (Tag 57035, a 5 mo deployment) traveled
to the southern shelf of New Caledonia, 2847 km
northwest of the Chatham Islands. The fourth shark, a
3.2 to 3.5 m TL male (Tag 57036, a 6 mo deployment)
moved to southern Vanuatu, having traveled 2884 km
from the tagging site (Fig. 1).
The Kalman filter-corrected tracks suggest that the
sharks traveled directionally to pop-up locations (Fig. 2).
Numerical results of the Kalman model fits are pro-
vided in Table 2. Sharks 57035 and 57036 visited the
northeastern coast of New Zealand before continuing
on a direct route to the tropical waters of New Caledo-
nia and Vanuatu. The estimated routes and swimming
speeds suggest that these sharks did not stop in coastal
waters of mainland New Zealand during their large-
scale movements.Estimated speeds during ocean travel-
ing were 89 to 130 km d–1 (3.7 to 5.4 km h–1; Table 1).
The 3 white sharks we tracked remained in the vicin-
ity of the Chatham Islands for 2.6 to 5.0 mo before
embarking on oceanic large-scale movements. They
left the Chatham Islands in late June (57033), early
July (57035), and early September (57036; Fig. 3).
Sharks 57035 and 57036 arrived in tropical waters in
early August and early October, respectively.
Vertical distribution
While at the Chatham Islands, all 3 sharks remained
in shallow water, rarely venturing below 75 m (Figs. 3
& 4). Most time (mean of 3 sharks = 81.8%) was spent
between 2 m and 50 m depth. The modal depth range
was slightly greater for shark 57035 (26 to 50 m) than
for the other 2 sharks (11 to 25 m).
During their ocean traveling phase, the vertical dis-
tribution of the sharks changed dramatically. All 3
sharks spent most time (mean 61.6%) at the surface
(0 to 1 m depth band) but made periodic deep dives.
Sharks 57033 and 57036 both dove to at least 901 m
(maximum PDT depths for both sharks were shallower
than the shallow limit of the deepest depth bin occu-
pied), and shark 57035 dove to at least 748 m (Fig. 3).
The vertical distribution pattern was bimodal, but this
effect is exaggerated by the unequal depth-bin sizes.
117
Table 2. Carcharodon carcharias. Numerical results of Kalman filter model fits. N: number of observations fitted to in each track;
LL: model log-likelihood; p: number of model free parameters; Est.: model parameter estimate; SD: model parameter standard de-
viation; u, v, and D: movement parameters from the Kalman transition equation; blong, blat, bSST, σlong, σlat, and σSST: bias and SD
parameters; a0and b0: solstice error model parameters from the measurement equation. See Nielsen et al. (2006) for a description
of model parameters and their derivation
Model parameters
Tag N LL puvDb
long blat bSST σlong σlat σSST a0b0
57033 59 –274.998 9 Est. 3.78 10.40 429.36 0 0.18 0 0.18 1.70 0.24 0.03 25.56
SD 0.83 0.97 82.04 0.45 0.17 0.30 0.03 0.02 5.11
57035 90 – 446.223 9 Est. 5.10 8.20 556.83 0 0.01 0 0.45 1.63 0.25 0.05 26.89
SD 1.15 0.86 74.72 0.36 0.08 0.27 0.03 0.02 4.27
57036 79 – 455.196 9 Est. 4.69 8.37 764.04 0 5.82 0 0.28 2.81 0.35 0.01 9.68
SD 1.08 1.81 91.34 0.52 0.07 0.28 0.02 0.01 3.03
Aquat Biol 8: 115– 123, 2010
After grouping the depth bins into equal 200 m inter-
vals, the mean percentages of time spent by the 3
sharks in each depth range were 76.7% at 0 to 200 m,
4.6% at 201 to 400 m, 8.3 % at 401 to 600 m, 9.2 % at
601 to 800 m, and 1.1% at 801 to 1000 m. The bimodal
pattern persisted, and had a minimum at 201 to 400 m,
indicating that the sharks traversed these depths rela-
tively quickly. The percentage of time spent by indi-
vidual sharks deeper than 400 m was 11 to 30% (mean
18.7%) and deeper than 600 m was 6 to 18 % (mean
10.4%; Fig. 4).
It was not possible to determine the frequency or
duration of deep dives because of the coarse temporal
resolution of the data (6 h time bins) and frequent gaps
in the data series because of incomplete transmission.
However, Shark 57033 made at least 2 dives deeper
than 800 m, Shark 57035 made at least 5 dives deeper
than 600 m, and Shark 57036 made at least 4 dives
deeper than 600 m (Fig. 3). Shark 57035 displayed a
third vertical distribution pattern in New Caledonian
waters, intermediate between those from the Chatham
Islands and while ocean traveling (Fig. 3). She spent
most of her time (74.0%) shallower than 100 m, but
with large amounts of time between 101 and 200 m
(12.6%) and 201 and 400 m (12.1 %). Only 1.2 % of her
time was spent deeper than 400 m.
Temperature ranges
While at the Chatham Islands, all 3 sharks experi-
enced similar, steadily declining water temperatures
as winter approached (Fig. 3). Maximum and minimum
temperatures differed little, consistent with the sharks
inhabiting the shallow mixed layer. Water temperature
was near 15°C when tags were deployed in April and
declined to about 12°C in late June to early July when
Sharks 57033 and 57035 departed, and about 11°C in
early September when Shark 57036 departed.
After departure from the Chatham Islands, maxi-
mum temperatures increased rapidly as the sharks
headed northwards into subtropical and tropical
118
Fig. 1. Southwest Pacific Ocean showing the tagging site (star) and other locations mentioned in the text. 1: Vanuatu; 2: New
Caledonia; 3: Louisville Seamount Chain; 4: Chatham Islands; 5: Campbell Island; A: Chatham Island; B: Star Keys; 100 m bathy-
metric contours are overlaid on the inset
Bonfil et al.: Tropical movements of NZ white sharks
waters. Shark 57035 reached a plateau of about 22°C,
and a maximum of 23.8°C in New Caledonian waters,
and Shark 57036 reached 23.4°C at the end of his
track in southern Vanuatu. During the ocean traveling
phase, minimum temperatures experienced by the
sharks fluctuated markedly in concert with their div-
ing behavior (Fig. 3). All sharks experienced tem-
peratures less than 8°C, with Sharks 57036 and 57033
recording the lowest values at 6.6°C and 6.4°C, respec-
tively.
As a result of their movement from temperate
to tropical latitudes and deep diving behavior, our
sharks experienced a wide range of temperatures (6.4
to 23.8°C). Temperature variations of 10 to 12°C were
often experienced in a single day by Sharks 57035
and 57036 (Fig. 3).
DISCUSSION
Geographic movements
The 3 white sharks successfully tracked
during this study appear to have remained at
the Chatham Islands for several months after
tagging and then made rapid, directed move-
ments to subtropical and tropical locations.
This is consistent with studies conducted
elsewhere describing white shark behaviors
ranging from site fidelity to trans-oceanic
migrations (Strong et al. 1992, Goldman &
Anderson 1999, Boustany et al. 2002, Bonfil
et al. 2005, Bruce et al. 2006, Weng et al.
2007a,b, Domeier & Nasby-Lucas 2008).
While our data do not provide unequivocal
evidence for residency because light-based
geolocation estimates are subject to error
particularly for latitude (Musyl et al. 2001,
Itoh et al. 2003), the most-probable position
estimates for the 3 sharks have relatively
small confidence regions and are tightly
grouped around the islands (Fig. 2). Addition-
ally, the steady decline in tag-recorded tem-
peratures as winter approached, and the
relatively shallow depths recorded during
this period are also consistent with the sharks
remaining in the vicinity of the Chatham
Islands for 2.6 to 5.0 mo after tagging.
The Chatham Islands sharks all made ex-
tensive oceanic movements, whereas most
other white sharks tagged in the Southern
Hemisphere have largely remained within
shelf waters when moving from temperate to
lower latitudes (Bonfil et al. 2005, Bruce et al.
2006). The most notable exceptions to this are
the trans-oceanic return migration of an im-
mature female white shark between South
Africa and Western Australia (Bonfil et al. 2005) and the
movement of a subadult female white shark between
South Australia and the northwest coast of New Zealand
(Bruce et al. 2006). The important difference between
these studies and ours is that in both southern Africa and
Australia, the continental shelf is continuous between
tropical and temperate regions, but the Chatham Islands
are in a temperate region where the continental shelf is
separated from subtropical and tropical shelves by ex-
tensions of the continental slope and submarine ridges.
Seasonal migration to subtropical and tropical latitudes
is a common white shark behavior elsewhere (Boustany
et al. 2002, Bonfil et al. 2005, Bruce et al. 2006, Weng et
al. 2007a, Domeier & Nasby-Lucas 2008), so it is not sur-
prising that white sharks inhabiting New Zealand waters
make long-distance, northward, oceanic movements.
119
Fig. 2. Carcharodon carcharias. ‘Most-probable’ tracks for tagged white
sharks; confidence regions (2 SE) surrounding each point are shown (orange)
Aquat Biol 8: 115– 123, 2010
Swimming speed
Chatham Island white sharks maintained high swim-
ming speeds (3.7 to 5.4 km h–1) during ocean crossings.
Previous estimates of white shark swimming speeds
maintained for several hours or longer are mainly
within the range of 2.9 to 4.5 km h–1 (Carey et al. 1982,
Strong et al. 1992, Boustany et al. 2002, Klimley et al.
120
Fig. 3. Carcharodon carcharias. Depth ranges traversed by 3 tagged white sharks and ambient water temperatures recorded by
the tags. Data represent minimum and maximum values recorded within a 6 h time interval. Vertical dashed lines indicate the
approximate date of departure of each shark from the Chatham Islands. The vertical dotted line in B indicates the approximate
time of arrival of shark 57035 at New Caledonia. Missing data mean that depth and temperature plots do not always correspond
with each other
Bonfil et al.: Tropical movements of NZ white sharks
2002, Bruce et al. 2006). However, a speed of 4.7 km
h–1was recorded during an ocean transit of ca.11100 km
in 99 d (Bonfil et al. 2005), and a maximum speed of
5.0 km h–1 was recorded for a shark tracked in the
northeast Pacific (Weng et al. 2007b). Fur-
thermore, Domeier & Nasby-Lucas (2008)
recorded a maximum speed of 8.0 km h–1
over a 24 h period for a white shark in the
northeast Pacific. Thus, white sharks can
make extended migrations at sustained
speeds of about 5 km h–1, or 120 km d–1. In
an analysis of 4 satellite-tracked Aus-
tralian sharks (1.8 to 3.6 m TL), Bruce et
al. (2006) found that swimming speed was
independent of shark length. In compari-
son, salmon sharks Lamna ditropis also
swim at relatively high speeds during
oceanic travel; Weng et al. (2008) reported
maximum swimming speeds of 4.29 km
h–1 for salmon sharks in the North Pacific.
Motivation for large-scale movements
Although the motivation for white shark
migrations is unknown, archival satellite
tag records from the northeast Pacific
suggest they may be related to foraging
(Weng et al. 2007a, Domeier & Nasby-
Lucas 2008). However, foraging chances
are likely to be higher in the areas to
which our white sharks are traveling from
New Zealand than in the vast oceanic
region to where northeast Pacific white
sharks are traveling. In our case, the tag
release points and pop-up dates coin-
cide with seasonal aggregations of large
whales, particularly humpback whales
Megaptera novaeangliae in tropical areas
(Gaskin 1976, Garrigue & Gill 1994,
Richards 2002, Garrigue & Russell 2004).
Data collected by Clua & Séret (in
press) indicate that white sharks occur
sporadically but consistently in New
Caledonian waters. They reported more
than 20 occurrences in the last 30 yr.
White sharks are known to scavenge on
whale carcasses (Carey et al. 1982, Long
& Jones 1996, Dudley et al. 2000) and
have also been observed to attack dis-
tressed juvenile southern right whales
Eubalaena australis (S. Burnell pers.
comm.). Most white shark records from
the Hawaiian Islands coincided with the
humpback whale calving season (Novem-
ber to May; Taylor 1985, Boustany et al. 2002, Weng et
al. 2007a, Domeier & Nasby-Lucas 2008), and similar
patterns are evident in Australia (Paterson & Paterson
1989, Bruce et al. 2006) and New Caledonia (Garrigue
121
Fig. 4. Carcharodon carcharias. Time spent by 3 white sharks at different
depths while at the Chatham Islands, ocean traveling, and (for Shark 57035
only) New Caledonia. N: sample sizes (number of days with data records) for
Chatham Islands, ocean traveling, and New Caledonia
Aquat Biol 8: 115– 123, 2010
& Gill 1994, Clua & Séret in press). The correlation of
white shark movements with those of large cetaceans
in different parts of the world suggests that white
sharks might travel to areas frequented by whales to
exploit windfall feeding opportunities.
More research, including further satellite tagging
and the development of techniques to remotely record
feeding events of sharks, needs to be carried out
before we can determine whether our preliminary
results of white shark large-scale movements are
indeed aimed at feeding on whales, whether they
return to the Chatham Islands after these large-scale
movements to the tropics, and whether such patterns
of spatial behavior are indeed seasonal, predictable,
and constitute part of a migration.
Vertical behavior
The 3 white sharks we tracked displayed a unimodal
depth distribution with a preference for depths of 2 to
50 m while at the Chatham Islands. They rarely dove
deeper than 75 m, although depths exceeding 100 m
exist within 9 km of the Star Keys tagging site. Prefer-
ences for depths shallower than 50 m have also been
displayed by white sharks near pinniped colonies else-
where (Strong et al. 1992, Goldman & Anderson 1999,
Boustany et al. 2002, Bruce et al. 2006, Hammerschlag
et al. 2006, Weng et al. 2007b).
This behavior pattern changed abruptly after the
sharks left the Chatham Islands. During ocean travel-
ling, the Chatham Islands sharks spent most of their
time at the surface (mean 62% at 0 to 1 m depth),
punctuated by dives below 600 m depth. The bimodal
depth distribution exhibited by the Chatham Islands
sharks during oceanic travel (Fig. 4) is essentially the
same as that shown by white sharks during oceanic
travel in the northeast Pacific and Indian Oceans
(Boustany et al. 2002, Bonfil et al. 2005, Weng et al.
2007a, Domeier & Nasby-Lucas 2008). These results,
and the regular receipt of satellite fixes from dorsal fin
tags that transmit when the aerial breaks the sea sur-
face (e.g. Bruce et al. 2006), indicate that white sharks
moving in oceanic waters travel mainly at the surface.
Diving to depths greater than 500 m is also a feature in
all of these studies, suggesting that surface migration
interspersed with deep diving is a routine behavioral
pattern for white sharks during ocean travel. Oscilla-
tory swimming behavior is common in large pelagic
fishes, including sharks, and may serve a variety of
functions in addition to foraging. These include ther-
moregulation (Carey & Scharold 1990), energy conser-
vation (Weihs 1973), and navigation using geomag-
netic and/or celestial cues (Klimley et al. 2002, Bonfil
et al. 2005).
Further research is required to understand the func-
tion of bimodal depth oceanic swimming behavior and
the mechanisms used by white sharks to navigate during
oceanic travel, and to determine whether white sharks
that leave New Zealand make return large-scale move-
ments such as those reported elsewhere (Bonfil et
al. 2005, Weng et al. 2007a). Such research could also
help elucidate population connectivity between the
Chatham Islands, mainland New Zealand, tropical is-
lands in the region, and Australia. The limited amount of
existing information on white shark movements in this
region suggests at least some movement between Aus-
tralia and the main islands of New Zealand (Pardini et al.
2001, Bruce et al. 2006). Despite the sparse and infre-
quent records of white sharks from the tropical islands of
the southwest Pacific, our data suggest that white sharks
may regularly travel there from New Zealand, possibly
drawn to humpback whale wintering and calving
grounds.
Acknowledgements. We thank T. and S. Gregory-Hunt, G.
King, and K. Scollay for their invaluable assistance in finding
and tagging of sharks; and C. Garrigue (Opération Cétacés,
Nouméa) for providing information on humpback whale
distribution and migration around New Caledonia and the
tropical South Pacific. The Wildlife Conservation Society, The
Roe Foundation, the New Zealand Foundation for Research
Science and Technology, and the New Zealand Department
of Conservation provided financial support for this project.
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123
Editorial responsibility: Brent Stewart,
San Diego, California, USA
Submitted: September 8, 2007; Accepted: December 4, 2009
Proofs received from author(s): January 1, 2010
... Yet, only seven of these animals (8%) conducted directed long-distance migrations between eastern Australia, New Zealand, New Caledonia and Papua New Guinea. In contrast, migration frequencies of white sharks previously tagged in New Zealand were much higher, with 95% of tagged individuals migrating to south Pacific islands and/or the Australian east coast 21,23 . Although ~70% of sharks tagged in New Zealand were immature, those sharks were generally larger (FL range: 244-410 cm, mean 326 cm, SD: 53) 21,23,30 than the sharks tracked in our study (FL range: 147-350 cm, mean 224 cm, SD 39), suggesting ontogenetic development of seasonal long-distance movements. ...
... variation in feeding niche, resource distribution, inter-annual oceanographic differences) [36][37][38] , rather than ontogeny alone. Oceanic travel speeds of the eight sharks crossing the Tasman Sea (mean 3.0 km −1 , range 2.4 to 3.8 km hour −1 ) were remarkable similar to swimming speeds recorded in previous studies 20,22,23,[39][40][41] and within the range of speeds estimated to minimize the metabolic cost of transport 42 . While large, regional tracking datasets like ours can help to resolve what proportion of the study population conducts frequent long-distance migrations 43 , horizontal movement data alone cannot verify the proximate mechanisms of migratory behaviour. ...
... Satellite data in this study is consistent with the hypothesis of several distinct migration corridors in the western South Pacific 20,21 (Supplementary Figure S1). Paths taken by sharks nos.179 (Chatham Islands, New Zealand to New Caledonia) and 234 (southwest South Island, New Zealand, to southern Queensland) (Supplementary Figure S1) were remarkably similar to the south-north migratory routes observed in several sharks previously tagged in New Zealand waters 21,23,49 . Although departure and arrival dates were not synchronous among sharks utilizing the same migration routes, they did fall within the same seasonal periods 21,23,25,50 . ...
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In Australian and New Zealand waters, current knowledge on white shark (Carcharodon carcharias) movement ecology is based on individual tracking studies using relatively small numbers of tags. These studies describe a species that occupies highly variable and complex habitats. However, uncertainty remains as to whether the proposed movement patterns are representative of the wider population. Here, we tagged 103 immature Australasian white sharks (147–350 cm fork length) with both acoustic and satellite transmitters to expand our current knowledge of population linkages, spatiotemporal dynamics and coastal habitats. Eighty-three sharks provided useable data. Based on individual tracking periods of up to 5 years and a total of 2,865 days of tracking data, we were able to characterise complex movement patterns over ~45° of latitude and ~72° of longitude and distinguish regular/recurrent patterns from occasional/exceptional migration events. Shark movements ranged from Papua New Guinea to sub-Antarctic waters and to Western Australia, highlighting connectivity across their entire Australasian range. Results over the 12-year study period yielded a comprehensive characterisation of the movement ecology of immature Australasian white sharks across multiple spatial scales and substantially expanded the body of knowledge available for population assessment and management.
... In the SWA population, although occasional offshore movements were observed, immature and adult sharks mainly occupy coastal waters on the continental shelf where they primarily target locally abundant pinnipeds Bruce et al., 2006;Meyer et al., 2019). Conversely, EA sharks show an ontogenetic (developmental) shift in habitat use, with immature sharks being mainly restricted to coastal waters Bruce et al., 2019) and larger individuals performing wide-spread movements across ocean basins to New Zealand and tropical Pacific islands (Duffy et al., 2012;Bonfil et al., 2010). As the east coast of Australia is devoid of primary seal colonies, coastal fish are the predominant prey for immature EA sharks (Grainger et al., 2020). ...
... In the EA population, Δ 199 Hg was positively correlated with shark total length (Fig. 3A). Previous studies of the EA white shark population have shown an ontogenetic increase in travelling behavior (Lee et al., 2021), with coastal areas dominated by small immature individuals Bruce et al., 2019;Grainger et al., 2020; and large sharks more likely to undertake large-scale offshore migrations (Duffy et al., 2012;Bonfil et al., 2010;Francis et al., 2015). Such an increase in offshore dispersal would result in greater exposure to pelagic MeHg sources, typically characterized by higher Δ 199 Hg values (Le Croizier et al., 2020b;Blum et al., 2013;Sackett et al., 2017) than MeHg produced in coastal habitats (Meng et al., 2020;Senn et al., 2010;Perrot et al., 2019), and would explain the ontogenetic variation in Δ 199 Hg found in EA sharks. ...
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Large marine predators exhibit high concentrations of mercury (Hg) as neurotoxic methylmercury, and the potential impacts of global change on Hg contamination in these species remain highly debated. Current contaminant model predictions do not account for intraspecific variability in Hg exposure and may fail to reflect the diversity of future Hg levels among conspecific populations or individuals, especially for top predators displaying a wide range of ecological traits. Here, we used Hg isotopic compositions to show that Hg exposure sources varied significantly between and within three populations of white sharks (Carcharodon carcharias) with contrasting ecology: the north-eastern Pacific, eastern Australasian, and south-western Australasian populations. Through Δ200Hg signatures in shark tissues, we found that atmospheric Hg deposition pathways to the marine environment differed between coastal and offshore habitats. Discrepancies in δ202Hg and Δ199Hg signatures among white sharks provided evidence for intraspecific exposure to distinct sources of marine methylmercury, attributed to population and ontogenetic shifts in foraging habitat and prey composition. We finally observed a strong divergence in Hg accumulation rates between populations, leading to three times higher Hg concentrations in large Australasian sharks compared to north-eastern Pacific sharks, and likely due to different trophic strategies adopted by adult sharks across populations. This study illustrates the variety of Hg exposure sources and bioaccumulation patterns that can be found within a single species and suggests that intraspecific variability needs to be considered when assessing future trajectories of Hg levels in marine predators.
... However, this remains at odds with movement patterns by this species in other areas of the world, where white sharks have been found to regularly exhibit offshore migratory movements and have spent as long as 1.5 years in areas of open ocean that were located several thousands of kilometres from the coast. Examples of oceanic behavioural stages include migrations by white shark in the southwest (Bonfil et al. 2010) and northeast Pacific Ocean (Nasby-Lucas et al. 2009) and the northern Atlantic Ocean (Skomal et al. 2017). ...
... Previously, white sharks in the Australian region had been characterised predominantly as shelf inhabitants (Bruce et al. 2006;McAuley et al. 2017). However, the recent evidence has identified some white sharks in this (Bruce et al. 2006;Bonfil et al. 2010;Bruce and Bradford 2012;Duffy et al. 2012). This study has demonstrated that within the SWA white shark population the use of off-shelf and slope waters is greater than previously thought; however, female white sharks may make greater use of off-shelf waters than their male counterparts. ...
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Large endothermic pelagic sharks are highly migratory and use habitats spanning a broad range of coastal, neritic and oceanic areas. This study aimed to resolve the current lack of information on the movements and habitat use of white sharks, Carcharodon carcharias, between shelf, slope and oceanic areas located off southwestern Australia. Movement behaviours, spatial distribution patterns and vertical habitat use of juvenile, sub-adult and adult white sharks ranging in size from 1.9 to 5.7 m total length were examined using 43 satellite tags deployed over 15 years. Pop-up satellite archival tags and satellite-linked radio tags collected 3663 days and > 109,900 km of tracking data over periods of up to 381 days. We demonstrated sex-based differences in movement and distribution patterns of male (21) and female (19) white sharks. Female dispersal was broader and extended further offshore than males, which largely remained in neritic and gulf habitats. Female white sharks experienced a narrower range of water temperatures (F = 9.0–19.0 °C; M = 10.4–24.8 °C). Despite these subtle differences, both sexes showed an affinity to the Neptune Island Group and the shelf slope canyons of the eastern Great Australian Bight, which are productive and oceanographically complex regions that support known prey of white sharks. This study highlighted that the southern-western Australian population of white sharks use off-shelf habitat to a greater extent than previously identified. Findings have potential implications for: ecological risk assessments of fisheries that operate in these offshore habitats and for monitoring and managing marine protected areas.
... El Tiburón Blanco (Carcharodon carcharias [Linnaeus, 1758]) es una especie que habita en las regiones subtropicales y templadas de todos los océanos, incluido el Mar Mediterráneo (Moro et al., 2019), y hace algunas incursiones en aguas tropicales (Duffy et al., 2012). Anteriormente se creía que esta especie era esencialmente costera, pero, con la ayuda de marcaje satelital y análisis genéticos, se ha documentado que los Tiburones Blancos realizan movimientos regulares hacia aguas oceánicas e inclusive entre distintos continentes (Pardini et al., 2001;Bonfil et al., 2005Bonfil et al., , 2010. Con base en análisis de secuencias de la región D-loop del ADN mitocondrial, se reconoce que existen seis clados monofiléticos asociados a Australia y Nueva Zelandia, Sudáfrica, Atlántico noroccidental, Mar Mediterráneo, Pacífico Noroeste y Pacífico Noreste (Tanaka et al., 2011), lo que sugiere la existencia de al menos seis subpoblaciones de esta especie a nivel mundial. ...
... El Tiburón Blanco (Carcharodon carcharias [Linnaeus, 1758]) es una especie que habita en las regiones subtropicales y templadas de todos los océanos, incluido el Mar Mediterráneo (Moro et al., 2019), y hace algunas incursiones en aguas tropicales (Duffy et al., 2012). Anteriormente se creía que esta especie era esencialmente costera, pero, con la ayuda de marcaje satelital y análisis genéticos, se ha documentado que los Tiburones Blancos realizan movimientos regulares hacia aguas oceánicas e inclusive entre distintos continentes (Pardini et al., 2001;Bonfil et al., 2005Bonfil et al., , 2010. Con base en análisis de secuencias de la región D-loop del ADN mitocondrial, se reconoce que existen seis clados monofiléticos asociados a Australia y Nueva Zelandia, Sudáfrica, Atlántico noroccidental, Mar Mediterráneo, Pacífico Noroeste y Pacífico Noreste (Tanaka et al., 2011), lo que sugiere la existencia de al menos seis subpoblaciones de esta especie a nivel mundial. ...
Book
El objetivo general del Programa de Acción para la Conservación de la Especie Tiburón Blanco (PACE) consiste en establecer una estrategia integral de investigación, protección y conservación del Tiburón Blanco en aguas mexicanas, que permita incrementar el conocimiento de la especie, robustecer las medidas de manejo para su aprovechamiento no extractivo sustentable y prevenir y mitigar las posibles amenazas para la especie y su hábitat.
... White sharks from multiple ocean basins have been shown to spend considerable time in coastal over-shelf waters with regular offshore, pelagic phases (Bonfil et al., 2005;Jorgensen et al., 2010;Domeier, 2012;Duffy et al., 2012;Bradford et al., 2020). At times, these pelagic phases can coincide in latitude or longitude with a typical population-level seasonal migration pattern (Weng et al., 2007a;Domeier andNasby-Lucas, 2008, 2013) or in contrast to the typical seasonal pattern (Bonfil et al., 2010;Skomal et al., 2017;Bradford et al., 2020;Spaet et al., 2020). Clarifying these movement phases in understudied white shark populations is critical given their designation as 'Vulnerable' by the IUCN (Rigby et al., 2019), their propensity to occupy coastal waters where there is potential for human-shark conflicts, and their naturally low population sizes as apex predators in marine food webs (Huveneers et al., 2018;Kock et al., 2018;Colefax et al., 2020). ...
Article
Full-text available
Understanding how mobile, marine predators use three-dimensional space over time is central to inform management and conservation actions. Combining tracking technologies can yield powerful datasets over multiple spatio-temporal scales to provide critical information for these purposes. For the white shark ( Carcharodon carcharias ), detailed movement and migration information over ontogeny, including inter- and intra-annual variation in timing of movement phases, is largely unknown in the western North Atlantic (WNA), a relatively understudied area for this species. To address this need, we tracked 48 large juvenile to adult white sharks between 2012 and 2020, using a combination of satellite-linked and acoustic telemetry. Overall, WNA white sharks showed repeatable and predictable patterns in horizontal movements, although there was variation in these movements related to sex and size. While most sharks undertook an annual migratory cycle with the majority of time spent over the continental shelf, some individuals, particularly adult females, made extensive forays into the open ocean as far east as beyond the Mid-Atlantic Ridge. Moreover, increased off-shelf use occurred with body size even though migration and residency phases were conserved. Summer residency areas included coastal Massachusetts and portions of Atlantic Canada, with individuals showing fidelity to specific regions over multiple years. An autumn/winter migration occurred with sharks moving rapidly south to overwintering residency areas in the southeastern United States Atlantic and Gulf of Mexico, where they remained until the following spring/summer. While broad residency and migration periods were consistent, migratory timing varied among years and among individuals within years. White sharks monitored with pop-up satellite-linked archival tags made extensive use of the water column (0–872 m) and experienced a broad range of temperatures (−0.9 – 30.5°C), with evidence for differential vertical use based on migration and residency phases. Overall, results show dynamic inter- and intra-annual three-dimensional patterns of movements conserved within discrete phases. These results demonstrate the value of using multiple tag types to track long-term movements of large mobile species. Our findings expand knowledge of the movements and migration of the WNA white shark population and comprise critically important information to inform sound management strategies for the species.
... White sharks tagged at Stewart Island and the Chatham Islands nearly all migrate to tropical and subtropical waters north of New Zealand (in an arc between the Great Barrier Reef of Australia and Tonga) during winter and spring (Bonfil et al. 2010;Duffy et al. 2012). A small number of sharks also migrate southwards along the New South Wales coast. ...
Technical Report
Full-text available
Eight fish species are currently protected in New Zealand fisheries waters: spotted black grouper (Epinephelus daemelii), white shark (Carcharodon carcharias), spinetail devilray (Mobula japanica), manta ray (Manta birostris), whale shark(Rhincodon typus), deepwater nurse shark (Odontaspis ferox), giant grouper (Epinephelus lanceolatus) and basking shark (Cetorhinus maximus). This study documents and describes their interactions with commercial fisheries in New Zealand waters, and locates and describes the available population information relevant to assessing the risk to these species.
... White sharks tagged at Stewart Island and the Chatham Islands nearly all migrate to tropical and subtropical waters north of New Zealand (in an arc between the Great Barrier Reef of Australia and Tonga) during winter and spring (Bonfil et al. 2010;Duffy et al. 2012). A small number of sharks also migrate southwards along the New South Wales coast. ...
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To gain insight into whale shark (Rhincodon typus) movement patterns in the Western Indian Ocean, we deployed eight pop‐up satellite tags at an aggregation site in the Arta Bay region of the Gulf of Tadjoura, Djibouti in the winter months of 2012, 2016, and 2017. Tags revealed movements ranging from local‐scale around the Djibouti aggregation site, regional movements along the coastline of Somaliland, movements north into the Red Sea, and a large‐scale (>1,000 km) movement to the east coast of Somalia, outside of the Gulf of Aden. Vertical movement data revealed high occupation of the top ten meters of the water column, diel vertical movement patterns, and deep diving behavior. Long‐distance movements recorded both here and in previous studies suggest that connectivity between the whale sharks tagged at the Djibouti aggregation and other documented aggregations in the region are likely within annual timeframes. In addition, wide‐ranging movements through multiple nations, as well as the high use of surface waters recorded, likely exposes whale sharks in this region to several anthropogenic threats, including targeted and bycatch fisheries and ship‐strikes. Area‐based management approaches focusing on seasonal hotspots offer a way forward in the conservation of whale sharks in the Western Indian Ocean.
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Full-text available
Purpose: Among 29 different species of sharks reported in the Adriatic, the great white shark and the basking shark are included as very rare species. These two species, like other sharks, have life history characteristics, such as slow growth, delayed ages at maturity, low fecundity and long gestation periods, that make them particularly vulnerable to overfishing. A number of studies carried out throughout the world indicate that numbers of these two species decline. Methods: This paper gives collected data of records of these two species in the Eastern Adriatic, based on bibliographical research and collaboration with numerous persons and institutions. Conclusion: Since 19th century 61 records of the great white shark and 27 records of the basking shark have been collected in the Eastern Adriatic. According to obtained results, a proposal of their protection in the same area has been presented.
Chapter
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We tested the ability of archival tags and their associated algorithms to estimate geographical position based on ambient light intensity by attaching six tags (three tags each from Northwest Marine Technologies [NMT] and Wildlife Computers [WC]) at different depths to a stationary mooring line in the Pacific Ocean (approx. 166º42'W, 24º00'N), for approximately one year (29- Aug-98 to 16-Aug-99). Upon retrieval, one tag each from the two vendors had malfunctioned: from these no data (NMT) or only partial data (WC) could be downloaded. An algorithm onboard the NMT tag automatically calculated geographical positions. For the WC tags, three different algorithms were used to estimate geographical positions from the recorded light intensity data. Estimates of longitude from all tags were significantly less variable than those for latitude. The mean absolute error for longitude estimates from the NMT tags ranged from 0.29 to 0.35º, and for the WC tags from 0.13 to 0.25º. The mean absolute error in latitude estimates from the NMT tags ranged from 1.5 to 5.5º, and for the WC tags from 0.78 to 3.50º. Ambient weather conditions and water clarity will obviously introduce errors into any geoposition algorithm based on light intensity. We show that by applying objective criteria to light level data, outliers can be removed and the variability of geographical position estimates reduced. We conclude that, although archival tags are suitable for questions of ocean basin-scale movements, they are not well suited for studies of daily fine scale movement patterns because of the likely magnitude of position estimate errors. For studies of fine scale movements in relation to specific oceanographic conditions, forage densities and distance scales of 100 km or less, other methods (e.g. acoustic tracking) remain the tool of choice.
Article
We investigated the migration and behavior of young Pacific bluefin tuna (Thunnus orientalis) using archival tags that measure environmental variables, record them in memory, and estimate daily geographical locations using measured light levels. Swimming depth, ambient water temperature, and feeding are described in a companion paper. Errors of the tag location estimates that could be checked were -0.54° ±0.75° (mean ±SD) in longitude and -0.12° ±3.06° in latitude. Latitude, estimated automatically by the tag, was problematic, but latitude, estimated by comparing recorded sea-surface temperatures with a map of sea-surface temperature, was satisfactory. We concluded that the archival tag is a reliable tool for estimating location on a scale of about one degree, which is sufficient for a bluefin tuna migration study. After release, tagged fish showed a normal swimming behavioral pattern within one day and normal feeding frequency within one month. In addition, fish with an archival tag maintained weight-at-length similar to that of wild fish; however, their growth rate was less than that of wild fish. Of 166 fish released in the East China Sea with implanted archival tags, 30 were recovered, including one that migrated across the Pacific Ocean. Migration of young Pacific bluefin tuna appears to consist of two phases: a residency phase comprising more than 80% of all days, and a traveling phase. An individual young Pacific bluefin tuna was observed to cover 7600 km in one traveling phase that lasted more than two months (part of this phase was a transpacific migration completed within two months). Many features of behavior in the traveling phase were similar to those in the residency phase; however the temperature difference between viscera and ambient temperature was larger, feeding was slightly more frequent, and dives to deeper water were more frequent.
Article
Geolocation data were recovered from archival tags applied to bigeye tuna near Hawaii. A state-space Kalman filter statistical model was used to estimate geolocation errors, movement parameters, and most probable tracks from the recovered data. Standard deviation estimates ranged from 0.5� to 4.4� latitude and from 0.2� to 1.6� longitude. Bias estimates ranged from )1.9� to 4.1� latitude and from )0.5� to 3.0� longitude. Estimates of directed movement were close to zero for most fish reaching a maximum magnitude of 5.3 nm day)1 for the one fish that moved away from its release site. Diffusivity estimates were also low, ranging from near zero to 1000 nm2 day)1. Low values of the estimated movement parameters are consistent with the restricted scale of the observed movement and the apparent fidelity of bigeye to geographical points of attraction. Inclusion of a time-dependent model of the variance in geolocation estimates reduced the variability of latitude estimates. The statespace Kalman filter model appears to provide realistic estimates of in situ geolocation errors and movement parameters, provides a means to avoid indeterminate latitude estimates during equinoxes, and is a potential bridge between analyses of individual and population movements.