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Movements, behavior and habitat preferences of juvenile white sharks Carcharodon carcharias in the eastern Pacific

Authors:
  • Virginia Institute of Marine Science, College of William & Mary

Abstract and Figures

Understanding of juvenile life stages of large pelagic predators such as the white shark Carcharodon carcharias remains limited. We tracked 6 juvenile white sharks (147 to 250 cm total length) in the eastern Pacific using pop-up satellite archival tags for a total of 534 d, demonstrating that the nursery region of white sharks includes waters of southern California, USA, and Baja California, Mexico. Young-of-the-year sharks remained south of Point Conception whereas one 3 yr old shark moved north to Point Reyes. All juvenile white sharks displayed a diel change in behavior, with deeper mean positions during dawn, day and dusk (26 +/- 15 m) than during night (6 +/- 3 m). Sharks occasionally displayed deeper nocturnal movements during full moon nights. On average, vertical excursions were deeper and cooler for 3 yr olds (226 +/- 81 m; 9.2 +/- 0.9 degrees C) than young-of-the-year animals (100 +/- 59 m; 11.2 +/- 1.4 degrees C). Juvenile white sharks are captured as bycatch in both US and Mexican waters, suggesting that management of fishing mortality should be of increased concern.
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MARINE ECOLOGY PROGRESS SERIES
Mar Ecol Prog Ser
Vol. 338: 211224, 2007
Published May 24
INTRODUCTION
The white shark Carcharodon carcharias is an apex
predator with a cosmopolitan distribution in temperate
and tropical waters of both hemispheres (Compagno
1984) and occurs rarely at boreal latitudes (Martin 2004).
Recent advances in our understanding of adult white
shark movements and habitat utilization have come
through the use of electronic tag technologies. Short-
term acoustic tracks off North America have revealed
that sharks prefer shallower depths (0 to 50 m) on the
continental shelf (Carey et al. 1982, Goldman et al. 1996,
Goldman 1997, Klimley et al. 2001). Longer satellite
tracks revealed that adult white sharks made large-scale
pelagic movements from the coastal waters of California
into the eastern and central Pacific as far west as Hawaii
(Boustany et al. 2002). During these offshore excursions
the white sharks occupied depths from the surface to
>980 m and encountered ambient temperatures from 4
to 24°C. Satellite tracking of white sharks in South Africa
(Bonfil et al. 2005) using fin-mounted Argos position tags
also revealed coastal and pelagic movements, with one
shark making an extensive trans-oceanic journey from
South Africa to Western Australia.
Few studies have focused on the juvenile life stages of
white sharks (Klimley et al. 2002, Dewar et al. 2004).
Klimley et al. (2002) acoustically tracked a single young-
of-the-year (YOY) white shark for 3.6 h near La Jolla,
California. This shark made oscillatory movements be-
tween the surface and 25 m depth. Over this depth range
© Inter-Research 2007 · www.int-res.com*Email: kevincmweng@gmail.com
Movements, behavior and habitat preferences
of juvenile white sharks Carcharodon carcharias
in the eastern Pacific
Kevin C. Weng
1,
*
, John B. O’Sullivan
2
, Christopher G. Lowe
3
, Chuck E. Winkler
4
,
Heidi Dewar
1
, Barbara A. Block
1
1
Tuna Research and Conservation Center, Hopkins Marine Station of Stanford University, 120 Ocean View Boulevard,
Pacific Grove, California 93950-3024, USA
2
Monterey Bay Aquarium, 886 Cannery Row, Monterey, California 93940-1023, USA
3
California State University, Long Beach, Department of Biological Sciences, 1250 North Bellflower Boulevard, Long Beach,
California 90840-0004, USA
4
Southern California Marine Institute, 820 South Seaside Avenue, Terminal Island, California 90731-7330, USA
ABSTRACT: Understanding of juvenile life stages of large pelagic predators such as the white shark
Carcharodon carcharias remains limited. We tracked 6 juvenile white sharks (147 to 250 cm total
length) in the eastern Pacific using pop-up satellite archival tags for a total of 534 d, demonstrating
that the nursery region of white sharks includes waters of southern California, USA, and Baja Cali-
fornia, Mexico. Young-of-the-year sharks remained south of Point Conception whereas one 3 yr old
shark moved north to Point Reyes. All juvenile white sharks displayed a diel change in behavior, with
deeper mean positions during dawn, day and dusk (26 ± 15 m) than during night (6 ± 3 m). Sharks
occasionally displayed deeper nocturnal movements during full moon nights. On average, vertical
excursions were deeper and cooler for 3 yr olds (226 ± 81 m; 9.2 ± 0.9°C) than young-of-the-year
animals (100 ± 59 m; 11.2 ± 1.4°C). Juvenile white sharks are captured as bycatch in both US and
Mexican waters, suggesting that management of fishing mortality should be of increased concern.
KEY WORDS: Juvenile white shark · Carcharodon carcharias · Habitat · Diel behavior · Satellite tag ·
Bycatch
Resale or republication not permitted without written consent of the publisher
Mar Ecol Prog Ser 338: 211224, 2007
the temperature dropped from 21 to 15°C. Dewar et al.
(2004) tracked an individual YOY white shark with a
pop-up satellite tag for 28 d near Long Beach, California.
This shark preferred mixed layer waters of 16 to 22°C but
made frequent movements through the thermocline to
temperatures as low as 9°C and depths of 240 m. Neither
animal moved out of the Southern California Bight
(SCB), however both were tracked for short durations.
Little is known about the breeding, parturition and
early life history phases of white sharks. Pregnant white
sharks have been captured near Japan, Taiwan, Aus-
tralia, New Zealand, in the Mediterranean, and off
Kenya (Bruce 1992, Fergusson 1996, Francis 1996,
Uchida et al. 1996, Anonymous 1999). YOY white sharks,
having total lengths <176 cm (Cailliet et al. 1985), have
been observed in these regions as well as in the SCB and
Baja California (Klimley 1985), the New York Bight
(Casey & Pratt 1985), southeastern Australia (Bruce
1992) and South Africa (Cliff et al. 1996). In the eastern
Pacific, the nursery habitat is hypothesized to include the
coast of North America south of Point Conception (Klim-
ley 1985). YOY white sharks have been captured in com-
mercial and recreational fisheries along this coast rela-
tively close to shore (Klimley 1985), but no pregnant
females have been captured in the region (Francis 1996),
and the breeding and parturition locations for white
sharks in the eastern Pacific remain unknown.
White sharks, like many large pelagic fishes and
sharks, are under increasing fishing pressure (Stevens et
al. 2000). The species is listed as ‘vulnerable’ by IUCN,
the International Union for Conservation of Nature and
Natural Resources (Fergusson et al. 2000) and is listed
under Appendix II of CITES, the Convention on Interna-
tional Trade in Endangered Species (Inskipp & Gillett
2005). Understanding the biology of both adult and juve-
nile white sharks is essential to the development of effec-
tive management strategies. The early life history stages
of a low-fecundity species such as the white shark are
particularly important, as fishing mortality is a more im-
portant factor in population dynamics than for a high fe-
cundity species (Mollet & Cailliet 2002). Juvenile white
sharks are captured in commercial fisheries off Califor-
nia (Klimley 1985) and Baja California, Mexico (O. Sosa-
Nishizaki pers. comm.) and in this study we identify im-
portant habitats of juvenile white sharks in this region of
the eastern Pacific.
MATERIALS AND METHODS
Satellite tagging of sharks. Pop-up satellite archival
tags (PAT 2.0 and 4.0, Wildlife Computers, Redmond,
WA, USA) were deployed on 6 juvenile white sharks
during 2002 to 2004 (Table 1). The tags were pro-
grammed to archive data at 30 or 60 s intervals. The
212
Table 1. Juvenile white sharks Carcharodon carcharias tagged during 20022004
Individual Sex Length Mass Age Days Start Start location Latitude Longitude End End location Latitude Longitude
(cm)
a
(kg)
b
(yr)
c
tracked date (°N) (°W) date (°N) (°W)
YOY-1 F 147 27 0.2 24
d
2 Jul 02 Channel Islands Harbor, CA
e
34.08 119.23 12 Aug 02 Ventura, CA
e
34.25 119.42
YOY-2 F 155 32 0.4 63 29 Jul 03 Ventura, CA
e
34.01 118.77 30 Sep 03 Hermosa Beach, CA
g
33.85 118.45
YOY-3 M 156 32 0.4 60 8 Sep 03 Long Beach, CA
e
33.68 118.24 7 Nov 03 Vizcaino Bay, BCN
h
28.49 114.29
YOY-4 M 155 32 0.4 37 20 Oct 03 Port Hueneme, CA
e
34.13 119.23 26 Nov 03 Ensenada, BCN
e
31.92 116.83
3YR-1 F 248 143 3.2 168 11 Aug 04 Will Rogers State Beach, CA
f
34.03 118.54 25 Jan 05 El Segundo, CA
g
33.88 118.50
3YR-2 F 250 146 3.3 182 12 Aug 04 Will Rogers State Beach, CA
f
34.03 118.54 10 Feb 05 Point Reyes, CA
h
37.98 122.87
a
Total length
b
After Kohler et al. (1995)
c
After Cailliet et al. (1985)
d
The shark was at liberty for 41 d, but the tag recorded only until 26 Aug 02, yielding a 24 d track
e
Captured in a commercial gillnet
f
Captured by hook and line
g
Tag popped up and was recovered
h
Tag popped up and was not recovered
Weng et al.: Movement of juvenile white sharks
archival data were compressed into bins of 2, 6 or 12 h
for transmission to Argos satellites. For each bin the
tag produced a depth-temperature profile and 2 histo-
grams, one of time-at-depth and one of time-at temper-
ature. In addition, a dawn and dusk light curve was
transmitted for each day.
Tags were deployed in the SCB on white sharks that
were captured in bottom-set gillnets as bycatch
(Table 1). Each PAT was attached to a titanium dart
(59 mm × 13 mm) with a 15 cm segment of 136 kg
monofilament line (300 lb test Extra-hard Hi-catch,
Momoi) covered with shrink-wrap (Block et al. 1998).
The dart was cleaned with Betadine microbicide
(Purdue Pharma) and inserted into the dorsal muscula-
ture at the base of the first dorsal fin using a stainless
steel applicator, such that the satellite tag trailed
behind the fin. To ease the insertion of the dart, a small
slit in the skin was made using a surgical scalpel.
We obtained data from all 6 of the white sharks
tagged. Four PAT tags were recovered after releasing
from sharks or when sharks were recaptured, provid-
ing full archival records of depth, temperature and
light, while the 2 remaining tags transmitted summary
data (Table 1).
Estimation of geopositions. To determine the move-
ments of each shark between the start and end posi-
tions, longitude was calculated from light levels (Hill &
Braun 2001) using software provided by the manufac-
turer (WC-GPE version 1.01.0005) and latitude was
estimated by matching sea surface temperature (SST)
measured by the tag to SST measured by satellites
along the estimated longitude (Smith & Goodman
1986, Teo et al. 2004) using MatLab (MathWorks). A
speed filter of 2.7 km h
–1
was used to filter the position
data, based on the speed for a juvenile white shark
obtained during an acoustic track by Klimley et al.
(2002). Given that this shark would travel 2.7 km h
–1
if
it made no turns or vertical movements, this speed fil-
ter is conservative.
Potential errors in geolocation were estimated by
comparing known deployment or endpoint locations to
estimated geolocations within 1 d. For error calcula-
tions, the geolocation algorithm was run with no limit
on daily movements rates so that there would be no
confounding effects of the speed filter.
Quantification of vertical and thermal habitat pref-
erences. The depth and temperature habitats of the
sharks were described using pressure and tempera-
ture data collected by the tags, and characterized in
terms of the surface mixed layer and thermocline. Ide-
ally, surface mixed layer depth is calculated according
to density, but since our tags do not measure salinity,
we used a definition of Δ1°C from the surface (Rao et
al. 1989). This depth was used to calculate the average
temperature of the surface mixed layer and the ther-
mocline. Time spent within the surface mixed layer
and the thermocline was calculated for individuals
with archival records (Sharks YOY-1, YOY-2, YOY-4
and 3YR-1); for transmitted records, bin margins for
the time-at-depth histograms typically did not corre-
spond to the surface mixed layer depth, so similar cal-
culations were not performed. However, in the case of
Shark 3YR-2, a time-at-temperature histogram bin
(20°C) corresponded closely to the mixed layer tem-
perature in the summer and autumn (19.8°C) and a
time-at-depth bin (50 m) corresponded closely to the
winter mixed layer depth (55 ± 1 m), so these values
were used.
Quantification of diel differences in depth and tem-
perature. To investigate diel patterns in habitat prefer-
ences, we used the light record in archival records to
divide the 24 h cycle into dawn, day, dusk and night
periods and then determined depth and temperature
preferences within these 4 periods, using MatLab. The
light record was corrected for light attenuation with
depth using the following light attenuation relation-
ship:
where Z is the depth, L
s
is the light at the surface, L
Z
is
the light measured by the tag at depth Z, and K is the
light attenuation coefficient. To allow the use of a
threshold value to separate twilight from day (or
night), between-day variation in L
s
was removed as
follows:
where w is the width of the moving average of L
s
, set to
the number of records per day. L
sc
is then L
s
without
interdiel trend and centered about zero. We defined
the periods of the diel cycle as follows:
where t is time, during dawn,
during dusk, and L
d
is the minimum L
s
during the day.
We conducted an analysis to determine if the light of
the moon affected the vertical distribution of juvenile
white sharks during nighttime periods. We selected
nighttime depths based on the light level measured by
the tag, as described above, and within these data
G
L
t
dk
s
=
Δ
Δ
G
L
t
dn
s
=
Δ
Δ
night
s
dn
s
dk s
:
Δ
Δ
Δ
Δ
L
t
G
L
t
GL<
∧>
∧<
()
L
d
dusk
s
dk
:
Δ
Δ
L
t
G
day
s
dn
s
dk s d
:
Δ
Δ
Δ
Δ
L
t
G
L
t
GLL<
∧>
∧>
(()
dawn
s
dn
:
Δ
Δ
L
t
G
LLL
wsc s s
()=−
LL
Z
KZ
=
s
e
213
Mar Ecol Prog Ser 338: 211224, 2007
compared 3 d periods centered on the full moon with
3 d periods centered on the new moon, as determined
from astronomical tables (Anonymous 2006).
RESULTS
Geographic movements
Six juvenile white sharks were tagged and released
in the Southern California Bight (SBC) between July
2002 and August 2004, and moved within waters
offshore of California and Baja California, Mexico
(Fig. 1). Young-of-the-year (YOY) sharks were tracked
for 46 ± 19 d (184 d in total) while 3 yr old sharks were
tracked for 175 ± 10 d (350 d in total) (Table 1). The
ranges of YOY and 3 yr old sharks overlapped in the
SCB but YOY sharks traveled further south, and 3 yr
old sharks moved further north. The 2 YOY sharks for
which we have data in the summer and early autumn
(Sharks YOY-1 and YOY-2) remained within the SCB
for the duration of their tracks (July and August to Sep-
tember, respectively). Shark YOY-1 was recaptured
near Ventura, California and Shark YOY-2’s satellite
tag popped up near Hermosa Beach, California. The
remaining YOY sharks were tracked during autumn
and traveled south into Mexican waters. Shark YOY-3
moved from the SCB to Vizcaino Bay, Baja California
between late September and mid October, traveling
700 km. Shark YOY-4 left the SCB during late Novem-
ber and was captured near Ensenada shortly there-
after. The 3 yr old sharks were tracked during autumn
and winter (Table 1). Shark 3YR-1 was tagged off the
SCB and remained within the SCB and waters off
northern Baja California for the 168 d of the track. The
satellite tag popped up near El Segundo, California on
25 January 2005. Shark 3YR-2 remained in the SBC
and waters off northern Baja California from August to
October and then moved north of Point Conception
during the first 9 d of November 2004. During the
remainder of the 182 d track the individual inhabited
waters off central and northern California, and the tag
released near Point Reyes on 25 January 2005, 600 km
from the tagging location and 4° farther north.
Accuracy of geolocations
Of the 6 sharks tagged in this study, light and SST
geolocation estimates were obtained within 1 d of the
start and end points for 6 of 12 possible pop-up end-
point events (Fig. 2). For these 6 events, the longitude
errors ranged from 80 km west to 103 km east, with
absolute error values averaging 54 ± 36 km (mean ±
SD). Latitude errors were all south, ranging from 17 to
434 km, with an average of 231 ± 159 km.
Vertical movements and diel patterns in behavior
Juvenile white sharks showed strong diel patterns in
behavior. During summer and autumn, when data
were available for all 4 individuals with archival
records (Sharks YOY-1, YOY-2, YOY-4, 3YR-1) mean
214
M
m
m
m
m
m
j
j
j
j
j
j
j
j
j
j
m
m
m
–122° –118° –114°
30°
34°
38°
j
m
m
m
m
#j
j
j
j
j
m
m
j
j
m
m
–122° –118° –114°
30°
34°
38°
n
h
Popup
Deploy
3YR-2
3YR-1
YOY-4
YOY-3
YOY-1
YOY-2
(a)
(b)
j
Fig. 1. Carcharodon carcharias. (a) Start and end positions for juvenile white sharks tracked off southern California, USA and
Baja California, Mexico. (b) Daily positions of juvenile white sharks based on light- and SST-based geolocations. Grey line:
1000 m depth contour
Weng et al.: Movement of juvenile white sharks
depths were within the thermocline during dawn (31 ±
19 m), day (26 ± 16 m) and dusk (22 ± 10 m) but in the
surface mixed layer at night (6 ± 3 m) (Figs. 3 & 4);
these depths were significantly shallower at night than
during other periods of the day (paired t-tests, p < 0.05;
Table 2). Consequently, the mean ambient tempera-
tures were cooler during dawn (15.8 ± 0.4°C), day
(16.8 ± 0.4°C) and dusk (16.6 ± 0.3°C) than during
night (18.2 ± 0.4°C) (Figs. 5 & 6). These temperatures
were significantly warmer during night than during
other periods of the day; in addition, dawn was signifi-
cantly cooler than day and dusk (paired t-tests, p <
0.05; Table 2). During winter, archival data were only
available for Shark 3YR-1 and it showed no diel pat-
terns in depth or temperature. The individual re-
mained at a depth of 4 ± 1 m and a temperature of 15.5
± 0.1°C, which was in the surface mixed layer.
In addition to comparing the average depths and
temperatures between periods of the day, we com-
pared the distributions of time-at-depth and time-at-
temperature between the 4 diel periods by summariz-
ing these variables into evenly spaced depth and
temperature bins. The same diel patterns emerged for
all 4 sharks. During summer and autumn, when data
were available for all 4 sharks, the shallower (Figs. 3 &
4) and warmer (Figs. 5 & 6) nighttime distributions
were significantly different from other periods of
the diel cycle (p < 0.05, Kolmogorov-Smirnov tests,
Table 3). A secondary peak of occupancy at depth
occurred during dawn, day and dusk for all 4 individu-
als, though the depth of this secondary peak was shal-
lower for YOY sharks (47 ± 23 m) than for the 3 yr old
(240 m). Shark 3YR-2 had a secondary peak in the 200
to 300 m bin, showing agreement with the archival
data for Shark 3YR-1. This secondary peak of occu-
pancy caused a secondary peak in temperature occu-
pancy during dawn, day and dusk, at 12.8 ± 1.9°C for
YOY sharks and 9.7 ± 0.3°C for the 3 yr old shark. Dur-
215
Longitude
Latitude
–400
–300
–200
–100
0
100
Error (km)
Fig. 2. Carcharodon carcharias. Error estimates for light- and
SST-based geolocations for 6 juvenile white sharks. Positive
values represent east and north; negative values west and
south. Boxplots: centerline, median; edges of box, 1st and 3rd
quartiles; whiskers, data points within the range Q1 – 1.5
(Q3 – Q1) to Q3 + 1.5 (Q3 – Q1)
Depth (m)
2 4 6 8 10 12 14 16 18 20 22 24
20
40
60
80
100
120
140
160
180
200
0
0
Depth (m)
Day
Dawn
Dusk
200
180
160
140
120
100
80
60
40
20
0
02040608060 40 20
Hour
% Time
Night
(a)
(b)
(c)
% Time
02040608060 40 20
10 12 14 16 18 20
Temperature (°C)
8 10 12 14 16 18 20
Temperature (°C)
0.1 0.3 0.7 1.8 5 14 37
% Time-at-depth
Fig. 3. Carcharodon carcharias. Diel changes in vertical movements for one young-of-the-year white shark (YOY-2). (a) Time-at-
depth through 24 h cycle during summer in the Southern California Bight. Color denotes amount of time spent at each depth.
White line: light intensity at the surface in arbitrary units. Time-at-depth histograms for (b) day and night and (c) dawn and dusk.
Blue lines: depth-temperature profile
Mar Ecol Prog Ser 338: 211224, 2007
ing winter, archival data were available only for shark
3YR-1, and this individual showed neither diel patterns
nor a secondary peak of occupancy in the thermocline.
During the course of their tracks, the 3 YOY sharks
undertook 2493 vertical excursions below the surface
mixed layer, while the 3 yr old shark (Shark 3YR-1) un-
dertook 1751 vertical excursions. The frequency and
duration of these vertical excursions did not differ
markedly between YOY and 3 yr old sharks, while the
mean depth of excursions was shallower for the YOY
animals. YOY sharks made 21 ± 9 vertical excursions
per day, while Shark 3YR-1 made 20 ± 11 vertical ex-
cursions per day, and the difference was not significant
(paired t-test, p = 0.69). The duration of excursions be-
216
Depth (m)
2 4 6 8 1012141618202224
40
80
120
160
200
240
280
320
360
400
0
0
400
350
300
250
200
150
100
50
0
Depth (m)
0 2040608060 40 20 0 20 40 60 8060 40 20
10 12 14 16 18 20
Temperature (°C)
8 10 12 14 16 18 20
Temperature (°C)
Day
Dawn
Dusk
Hour
% Time
Night
(a)
(b)
(c)
% Time
0.1 0.3 0.7 1.8 5 14 37 % Time-at-depth
Fig. 4. Carcharodon carcharias. Diel changes in vertical movements for one 3 yr old white shark (3YR-1). (a) Time-at-depth
through 24 h cycle during autumn in the Southern California Bight. Color denotes amount of time spent at each depth. White line:
light intensity at the surface in arbitrary units. Time-at-depth histograms for (b) day and night and (c) dawn and dusk. Blue lines:
depth-temperature profile
6
8
10
12
14
16
18
20
22
24
Temperature (°C)
2 4 6 8 10121416182022
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
30 20 10 0 10 20 30 40
Day
Dawn
Dusk
Hour
% Time
Night
(a)
(b)
(c)
24
0
30 20 10 0 10 20 30 40
% Time
Temperature (°C)
0.1 0.3 0.7 1.8 5 14 37
% Time-at-
temperature
30 20 10 0 10 20 30 40
% Time
30 20 10 0 10 20 30
% Time
Fig. 5. Carcharodon carcharias. Diel changes in temperature preferences for a young-of-the-year white shark (YOY-2). (a) Time-
at-temperature through 24 hr diel cycle during summer in the Southern California Bight. Color denotes amount of time spent at
each temperature. White line: light intensity at the surface in arbitrary units. Time-at-temperature histograms for (b) day and
night and (c) dawn and dusk
Weng et al.: Movement of juvenile white sharks
low the surface mixed layer was similar for YOY sharks
(0.7 ± 1.3 h) and the 3 yr old shark (0.8 ± 1.5 h) (paired
t-test, p = 0.30). However, the duration of the longest
excursion during each day was significantly greater for
the 3 yr old shark (5.1 ± 3.0 h) than the YOY sharks (3.9 ±
3.2 h) (paired t-test, p = 0.01). Maximum depths were
greater during dawn, day and dusk (157 ± 80 m) than
during night (56 ± 40 m) for the 4 individuals with
archival records (paired t-test, p < 0.01) (Fig. 7). Mini-
mum temperatures were significantly
cooler during dawn, day and dusk
(10.2 ± 1.1°C) than during night (12.2 ±
1.7°C) (paired t-test, p = 0.05). There
was a strong contrast in the depth of ex-
cursions into the thermocline between
age classes, with YOY sharks having
significantly shallower excursions (100
± 59 m) than the 3 yr old shark (226 ± 81
m) (paired t-test, p = 0.02). The 3 yr old
shark reached significantly cooler temperatures during
excursions into the thermocline (9.2 ± 0.9°C) than the
YOY sharks (11.2 ± 1.4°C) (paired t-test, p < 0.01). The
greatest depth and coolest temperature reached by
each individual during its track was deeper and cooler
for 3 yr olds (394 ± 14 m; 8.4 ± 0.3°C) than for YOY ani-
mals (241 ± 82 m; 9.4 ± 0.6°C) (paired t-test for depth,
p = 0.02; paired t-test for temperature, p = 0.03).
We compared nighttime depths between full moon
and new moon periods (Fig. 8). The median nighttime
depths were greater during full moon periods than new
moon periods for 3 of the 4 sharks (Sharks YOY-2,
YOY-4, 3YR-1). For Sharks YOY-2, YOY-4 and 3YR-1,
nighttime full moon depths (7 ± 4 m) were significantly
greater than nighttime new moon depths (3 ± 2 m)
(Wilcoxon rank sum tests, p < 0.05). Shark YOY-1 did not
show greater nighttime depths during full moon periods.
Potential benthic foraging events, as indicated by
vertical excursions to consistent or gradually changing
bottom depths (Fig. 8b), were noted on 63 ± 10% of all
days for which archival data were obtained (Sharks
217
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
6
8
10
12
14
16
18
20
22
24
Temperature (°C)
Temperature (°C)
2 4 6 8 10 12 14 16 18 20 22
30 20 10 0 10 20 30 40
Day
Dawn
Dusk
Hour
% Time
Night
(a)
(b)
(c)
24
0
30 20 10 0 10 20 30 40
% Time
0.1 0.3 0.7 1.8 5 14 37
% Time-at-
temperature
30 20 10 0 10 20 30 40
30 20 10 0 10 20 30
% Time % Time
Fig. 6. Carcharodon carcharias. Diel changes in temperature preferences for a 3 yr old white shark (3YR-1). (a) Time-at-temper-
ature through 24 hr diel cycle during autumn in the Southern California Bight. Color denotes amount of time spent at each tem-
perature. White line: light intensity at the surface in arbitrary units. Time-at-temperature histograms for (b) day and night and
(c) dawn and dusk
Table 2. P-values from paired t-tests on data for Sharks YOY-1, YOY-2, YOY-3
and 3YR-1 during summer and autumn for average depth and temperature dur-
ing diel periods. *: statistically significant
Test Dawn Day Dusk Dawn Dawn Dusk
vs. night vs. night vs. night vs. day vs. dusk vs. day
Depth (a > b) 0.04* 0.05* 0.03* 0.36 0.22 0.66
Temperature (a < b) 0.00* 0.00* 0.00* 0.01* 0.00* 0.24
Table 3. P-values from Kolmogorov-Smirnov tests for distrib-
utions of time-at-depth and time-at-temperature during diel
periods. *: statistically significant
Shark Variable Dawn Day Dusk
vs. night vs. night vs. night
YOY-1 Depth 0.155 0.797 0.797
YOY-2 Depth 0.000* 0.000* 0.000*
YOY-4 Depth 0.000* 0.000* 0.000*
3YR-1 autumn Depth 0.000* 0.000* 0.001*
3YR-1 winter Depth 1.000 1.000 1.000
Mar Ecol Prog Ser 338: 211224, 2007
YOY-1, YOY-2, YOY-4 and 3YR-1). YOY sharks under-
took benthic foraging on 67 ± 3% of all days, compared
to 48% for the 3 yr old shark. The value for Shark 3YR-
1 remained the same if the comparison was conducted
during summer and autumn only.
Depth and temperature preferences
The pressure and temperature data recorded on the
PAT tag enabled reconstruction of the vertical thermal
structure along the tracks of the sharks (Fig. 9). YOY
sharks occupied waters with surface temperatures
ranging from 15.0 to 23.4°C, and the surface mixed
layer had an average depth of 8 ± 2 m (mean ±SD) and
an average temperature of 18.8 ± 0.2°C. Below the sur-
face mixed layer, waters occupied by YOY sharks
averaged 13.8 ± 1.7°C. YOY sharks spent 64 ± 19% of
their time in the surface mixed layer and 36 ± 19% of
their time in the thermocline. Temperatures encoun-
tered by YOY sharks ranged from 23.4°C (Shark
YOY-2) to 8.6°C (Shark YOY-3).
Three year old sharks (Sharks 3YR-1 and 3YR-2)
inhabited waters similar to those of YOY sharks during
the summer and autumn, spending 53 ± 0% of the time
in the surface mixed layer with an average depth of 9 ±
0 m and an average temperature of 19.2 ± 0.8°C, and
47 ± 0% of the time in thermocline waters averaging
13.4 ± 1.6°C. During the winter (December to Febru-
ary) the 3 yr old sharks spent 93 ± 9% of their time in a
deeper, colder surface mixed layer averaging 45 ±
15 m and 14.3 ± 1.8°C; and 7 ± 9% of their time in the
thermocline in average temperatures of 13.0 ± 0.1°C.
Temperatures encountered by 3 yr old sharks ranged
from 24.0°C (Shark 3YR-2) to 8.4°C (Shark 3YR-1).
The depth and temperature distributions of the juve-
nile white sharks showed differences between YOY
and 3 yr old age classes. YOY sharks inhabited tem-
peratures below 10°C only 1 ± 2% of the time, com-
pared to 10 ± 1% of the time for 3 yr old sharks during
the same seasons (paired t-test, p < 0.01).
Seasonal patterns of mixed layer occupancy and
maximum depth
Vertical and thermal habitats were compared across
seasons (autumn and winter) for the 3 yr old sharks
that were tracked into the winter months. For Sharks
3YR-1 and 3YR-2 a seasonal cooling of the mixed
layer in winter, as well as during movements north of
Point Conception, coincided with a near cessation of
vertical movements into the thermocline resulting in a
constriction of the habitat to the surface mixed layer
(Fig. 10). During summer and autumn, when mixed
layer temperatures averaged 19.2 ± 0.8°C, both sharks
frequently made excursions to depths >300 m, where
water temperatures averaged 13.4 ±
1.6°C, and spent 18 ± 2% of the time in
waters cooler than 12°C; calculation of
time within thermocline waters was
not possible for shark 3YR-2, so 12°C
was used as a threshold instead. Dur-
ing winter, when mixed layer tem-
peratures averaged 14.3 ± 1.8°C, the
2 sharks avoided thermocline waters
even though the temperature of this
layer (13.0 ± 0.1°C) was similar to its
temperature during summer and au-
tumn, spending only 0.4 ± 0.0% of the
time in waters cooler than 12°C (paired
t-test, p = 0.05). The maximum depth
reached by the sharks was positively
218
Dawn Day Dusk Night
0
50
100
150
200
250
300
Depth (m)
Fig. 7. Carcharodon carcharias. Maximum depths during
dawn, day, dusk and night for a juvenile white shark (YOY-2).
Boxplots: centerline, median; edges of box, 1st and 3rd quar-
tiles; whiskers, data points within the range Q1 – 1.5 (Q3 – Q1)
to Q3 + 1.5 (Q3 – Q1); +: points lying outside this range
200
150
100
50
0
200
150
100
50
0
7 Sep
8 Sep
23 Sep
24 Sep
Depth (m)
Depth (m)
(a)
(b)
Fig. 8. Carcharodon carcharias. Vertical movements of a juvenile white shark
(YOY-2) for two 48 h periods during (a) full moon, (b) new moon. Lines show
depth measured at 60 s intervals; grey boxes: nighttime
Weng et al.: Movement of juvenile white sharks
correlated with surface temperature
(least squares regression, r
2
= 32.7, p <
0.01).
Bycatch of juvenile white sharks in
fisheries
In this study, 4 YOY white sharks
were caught in US and Mexican bot-
tom-set gillnets 6 times (Table 1). All
YOY sharks were initially captured in
gillnets and 2 sharks (YOY-1 and YOY-
4) encountered gillnets a second time.
Shark YOY-1 encountered a gillnet
near Ventura, California, USA and
escaped, but left its satellite tag behind
in the net. Shark YOY-4 was recap-
tured by a gillnet fisherman near Ense-
nada, Baja California, Mexico.
219
08/27 09/13 09/30 10/17 11/03 11/20 12/07 12/24 01/10
0
50
100
150
200
250
300
350
400
08/04 08/10 08/16 08/22 08/29 09/04 09/10 09/16 09/22
0
50
100
150
200
250
300
350
400
10 12 14 16 18 20 22824
Temperature (°C)
Depth (m)
(a)
(b)
Fig. 9. Carcharodon carcharias. Time series of water column thermal structure for (a) Shark YOY-2 and (b) Shark 3YR-1. Extent
of the profile: maximum depth reached on a given day. Color denotes ambient water temperature
Temperature (°C)
Depth (m)
10 12 14 16 18 20 22 24
0
40
80
120
160
200
240
280
320
360
400
5
10
15
20
25
30
35
Number of Observations
Fig. 10. Carcharodon carcharias. Frequency of depth-temperature observations
for two 3 yr olds (3YR-1, 3YR-2). Color denotes number of observations at each
depth and temperature
Mar Ecol Prog Ser 338: 211224, 2007
DISCUSSION
Nursery region of white sharks in
the eastern Pacific
In this study we tracked 6 juvenile white sharks in
the eastern North Pacific over durations of 24 to 182 d
and have provided new information on their seasonal
movements, behavior and habitat utilization. The ap-
parent residency of sharks in the California Current
system off California and Baja California suggests that
this region is an important nursery habitat for juvenile
white sharks (Fig. 1). YOY sharks tracked during sum-
mer (Sharks YOY-1 and YOY-2) remained within the
Southern California Bight (SCB), whereas YOY sharks
tracked in autumn (YOY-3 and YOY-4) moved south
into waters of Baja California, Mexico. The two 3 yr old
sharks were tracked from late summer through winter,
with one remaining in the SCB and northern Baja Cal-
ifornia waters (Shark 3YR-2), overlapping the range of
the YOY sharks, and the other moving north of Point
Conception into central and northern California waters
(Shark 3YR-1).
The results presented here extend the nursery
region for white sharks south of the SCB, expanding
the area described by Klimley (1985), and indicating
that juvenile white sharks located in US and Mexican
waters are most likely part of the same population.
Juvenile white sharks have also been captured inside
the Gulf of California (Klimley 1985, O. Sosa-Nishizaki
pers. comm.). Our results suggest that the expansion of
the nursery may be associated with season, as YOY
sharks tracked in the summer remained in the SCB,
while those tracked in the autumn moved south into
Mexican waters. Longer tracks are required to deter-
mine the full extent of the nursery grounds in the east-
ern Pacific and whether subpopulations exist.
Putative nursery areas exist in other regions of the
world, and in both the northern and southern hemi-
spheres, captures of pregnant and YOY sharks occur
most frequently during spring and summer (Casey &
Pratt 1985, Bruce 1992, Cliff et al. 1996, Fergusson
1996, Francis 1996, Uchida et al. 1996). In our study,
sea surface temperatures occupied by YOY sharks
ranged from 15.0 to 23.4°C. For the seasons of YOY
and pregnant shark captures in other putative nursery
areas, climatological temperatures are 19 to 22°C in
southern Japan; 20 to 22°C in Taiwan; 21 to 26°C in
eastern South Africa; 20 to 23°C in southeastern Aus-
tralia; 16 to 20°C in northern New Zealand; 20 to 26°C
in the central Mediterranean; and 17 to 24°C in the
Mid-Atlantic Bight (Anonymous 2005). The similarity
in water temperature in all of these regions suggests
that there may be an optimal thermal environment for
YOY white sharks.
Larger juvenile white sharks appear to have a different
geographic range and seasonal pattern than YOY ani-
mals. While both year classes of sharks appear to enter
Mexican waters at various points, 3 yr old individuals re-
turned to California waters and remained there during
the winter. Shark 3YR-2 moved north of Point Concep-
tion, into the primary nearshore habitat of adult white
sharks. Since this individual was a 3 yr old of 2.5 m
length, and fish predominate in the diets of white sharks
<3 m in length (Tricas & McCosker 1984), the northward
movements of juvenile sharks are probably not associ-
ated with the addition of mammals to the diet (Klimley
1985). Differences in track duration may bias the geo-
graphic ranges covered (Block et al. 2005), so longer
tracks on YOY sharks may show more overlap with the
3 yr old sharks. Conversely 3 yr old sharks may be re-
vealing a niche expansion to the north that YOY sharks
cannot physiologically tolerate (Weng et al. 2005).
Accuracy of geopositions
Long distance movements of individual sharks
between the SCB, Baja California, and northern Cali-
fornia were demonstrated by satellite-derived pop-up
endpoint positions and recapture positions, with inter-
mediate positions calculated using light and SST based
geolocation. The geoposition errors for juvenile white
sharks in this study (54 ± 15 km zonally, 231 ± 64 km
meridionally; Fig. 2) meant that the data were useful in
characterizing movements out of the SCB, but not
within the SCB. As in the validation study of Teo et al.
(2004), longitude errors for juvenile white sharks are
smaller than latitude errors. However, the latitude
errors for juvenile white sharks are all to the south,
indicating a systematic bias which was not observed
by Teo et al. (2004). The use of SST to determine lati-
tude (Smith & Goodman 1986) is most accurate in
regions where greater north-south gradients in SST
exist; the gradient is monotonic over scales greater
than a degree of latitude; there are no large gaps in
SST data, as occur in areas with high cloud cover or
near land; and the scale of movements is much larger
than the scale of errors. Teo et al. (2004) estimated root
mean square latitude errors of 163 km, 129 km and
100 km for salmon sharks Lamna ditropis, blue sharks
Prionace glauca and bluefin tuna Thunnus thynnus,
respectively. These highly migratory pelagic species
travel hundreds or thousands of kilometers in primarily
offshore waters. The present study takes place in
coastal, upwelled waters with a much finer scale of
variability in SST, which most likely explains the
slightly higher error estimates we obtained. Further-
more, the high cloud cover in the region reduces the
coverage of satellite data.
220
Weng et al.: Movement of juvenile white sharks
Diel patterns in depth and temperature
The 30 s and 60 s archival data sets obtained from
4 white sharks provided the opportunity to conduct a
detailed analysis of behavior over diel and lunar
time scales, across a range of habitats. Juvenile white
sharks make deeper vertical movements during day,
dawn and dusk than during night (Figs. 3 & 4). Dewar
et al. (2004) also noted a peak in activity in a juvenile
white shark in the SBC at sunrise. Twilight activity has
been noted in a wide range of pelagic fishes including
tunas (Thunnini) (Dagorn et al. 2000, Kitagawa et al.
2000, Schaefer & Fuller 2002), billfishes (Xiphidae,
Istiophoridae) (Carey & Robison 1981, Holland et al.
1990a) and mako sharks Isurus oxyrinchus (Sepulveda
et al. 2004). Stomach content analysis indicates that
these dawn/dusk activity peaks are often associated
with feeding (Buckley & Miller 1994, Scott & Cattanach
1998), although feeding may also occur during the day
(Reintjes & King 1953) or night (Holland et al. 1990b).
Vertical excursions into the thermocline comprise a
small portion of the animals’ time, but may be ecologi-
cally important if they constitute foraging behavior.
Sepulveda et al. (2004) used stomach temperature data
to confirm feeding events on vertical excursions by
mako sharks. Similar studies on juvenile white sharks
would help to confirm whether this behavior is for
foraging.
During the nighttime, the moon phase influenced the
occurrence and depth of vertical excursions by juve-
nile white sharks (Fig. 8). Vertical excursions into the
thermocline occurred more frequently and to greater
depths during full moon nights as compared to new
moon nights. Increased depth during full moon periods
may be associated with the deeper depth of the prey
species (squids, fishes, zooplankton), which undergo
light-mediated vertical migrations (Ringelberg & van
Gool 2003). This also suggests that during the full
moon, the juvenile white sharks are foraging at night.
Depth and temperature preferences
Tagging data indicate that the primary habitat of
juvenile white sharks is in the surface mixed layer, but
that they make extensive use of the cooler waters of
the thermocline. The preference for surface mixed
layer waters results in occupancy of the warmest
waters within the California Current, ranging from 16
to 20°C (Figs. 5 & 6). This habitat preference is similar
to those of the sharks tracked by Klimley et al. (2002)
and Dewar et al. (2004), which showed a preference for
waters of 15 to 21 and 16 to 22°C respectively. These
temperatures are characteristic of nearshore SCB
waters during summer and autumn (Venrick et al.
2003). Occupancy of cooler waters in the thermocline
by juvenile white sharks was higher in this study than
in previous studies. During summer and autumn, YOY
white sharks spent 32 ± 20% of their time in waters
cooler than 16°C, as compared to 11% of the time for
the white shark tracked by Dewar et al. (2004) and
25% by the white shark tracked by Klimley et al.
(2002). The greater occupancy of cooler waters ob-
served here likely results from the longer tracks cap-
turing a wider variety of behavior: 46 ± 19 d in the pre-
sent study, vs. 0.15 and 28 d in the studies of Klimley
et al. (2002) and Dewar et al. (2004), respectively. The
lack of data for YOY sharks during the winter leaves
open the possibility that this age class may encounter
cooler habitats if tracked during this period.
The 3 yr old sharks tracked in this study inhabited
similar water masses to the YOY sharks during sum-
mer and autumn, but utilized the habitat differently.
These older and larger sharks made deeper vertical
excursions, and as a result, their depth distributions
were significantly deeper (Fig. 4) and temperature dis-
tributions significantly cooler (Fig. 6). A similar result
was found for juvenile mako sharks by Sepulveda et al.
(2004). The niche expansion of white sharks into cooler
habitats appears to continue beyond the 3 yr old phase,
as adult white sharks occupy waters ranging from 4 to
25°C (Lowe & Goldman 2001, Boustany et al. 2002) and
enter boreal habitats (Martin 2004).
Foraging habitat of juvenile white sharks
The large proportion of time juvenile white sharks
spent in the surface mixed layer indicates that this may
be an important foraging habitat. Stomach content
analysis shows that nearshore pelagic fishes are in the
diet of juvenile white sharks, including Pacific sardine
Sardinops sagax, king salmon Oncorhynchus tshawyt-
scha, white seabass Cynoscion nobilis and striped bass
Morone saxatilis (Klimley 1985). Other potential prey
species that inhabit the water column in the study area
include grunion Leuresthes tenuis, surfperch Hyper-
prosopon spp., smelt Atherinops spp., croaker Geny-
onemus spp., mackerel Scomber spp., barracuda Sphy-
raena argentea and market squid Loligo opalescens.
Our data indicate that benthic foraging is also impor-
tant for juvenile white sharks (Fig. 8b). Behavior indi-
cating benthic foraging was observed on 63 ± 10%
of all days for sharks with archival records. Similar
behaviors were noted by Dewar et al. (2004), and stom-
ach content studies show a variety of demersal fishes in
the diet of juvenile white sharks including the bat ray
Myliobatis californica, cabezon Scorpaenichthys mar-
moratus, soupfin shark Galeorhinus zygopterus, grey
smooth-hound Mustelus californicus, spiny dogfish
221
Mar Ecol Prog Ser 338: 211224, 2007
Squalus acanthius, lingcod Ophiodon elongatus, rock
crab Cancer antennarius, and rockfish Sebastes spp.
(Klimley 1985). The secondary peak of occupancy at
depth (47+23 m for YOY sharks, Fig. 3; 240 m for 3 yr
olds, Fig. 4) is the aggregate time of vertical excursions
and may be an indicator of foraging effort. There are
large depth-associated changes in the species assem-
blages of fishes off California and Baja California, so
the depth range of a predator determines the forage
species it can access. At the depth range of the sec-
ondary occupancy peak for YOY sharks, other poten-
tial forage species include shallow-living soft-substrate
demersal fishes such as halibut Paralichthys californi-
cus, sanddabs Citharichthys spp; shallow hard-sub-
strate fishes such as copper rockfish Sebastes caurinus,
vermilion rockfish S. miniatus, lingcod Ophiodon elon-
gatus and painted greenling Oxylebius pictus; or elas-
mobranches such as round stingray Urobatis halleri,
California skate Raja inornata and leopard shark Tri-
akis semifasciata (Bond et al. 1999, Love et al. 2000).
Forage species accessible to 3 yr old sharks could
include deeper-living soft-substrate fishes such as tur-
bot Hypsopsetta spp., Pleuronichthys spp. and sole
Microstomus spp., and deep-living hard-substrate
fishes such as greenspotted rockfish S. cholorostictus,
flag rockfish S. rubrivinctus and bocaccio S. pausispi-
nus (Bond et al. 1999, Love et al. 2000).
The closely related shortfin mako shark, which is
abundant in the SCB, appears to utilize thermocline
waters less than juvenile white sharks. Shortfin mako
sharks of a size intermediate between YOY and 3 yr
old sharks in this study (1.8 m), tracked in waters of the
SCB, showed only occasional use of the thermocline
and spent only 3.7 ± 3.2% of the time in waters cooler
than 16°C (Holts & Bedford 1993). This suggests that
there may be some resource partitioning between
these species, with mako sharks utilizing epipelagic
resources and white shark potentially making use of
both epipelagic and demersal resources.
Thermal limitation of habitat
A number of results in this study are consistent with
thermal limitation in juvenile white shark habitat uti-
lization, and a niche expansion into cooler habitats
with growth. The southward movement of YOY ani-
mals during the autumn, when mixed layer tempera-
tures in the SCB are falling, is consistent with move-
ments to avoid cooler winter temperatures. The greater
depths and cooler temperatures of vertical excursions
undertaken by 3 yr olds, in comparison to YOY sharks
occupying the same region during the same season
(summer and autumn in the SCB), are consistent with
an expansion of thermal habitat with body size. The
northward movement of one 3 yr old shark into waters
north of Point Conception, where YOY individuals are
rare (Klimley 1985), is consistent with a thermally
mediated geographic range expansion with body size.
The cessation of excursions into the thermocline by
3 yr old sharks when surface mixed layer temperatures
fall below 16°C is consistent with behavioral ther-
moregulation (Carey & Scharold 1990, Holland et
al. 1992). However, the observation could also be
explained by patterns in the vertical distribution of
prey. It is important to note the bias caused by the
longer tracks of 3 yr olds, extending into the winter, as
compared to the tracks of YOY sharks that were lim-
ited to summer and autumn. However, comparisons of
depth and temperature using only data for summer
and autumn did reveal deeper and cooler habitat uti-
lization by 3 yr olds.
Recent physiological studies have indicated that
pelagic fish may have cardiac limitations when enter-
ing cold waters. A cold induced bradycardia is evident
in tunas (Korsmeyer et al. 1997, Blank et al. 2002,
2004). Although few studies have investigated the
influence of cooler temperatures on in vivo cardiac
performance in lamnid sharks, it is possible that a sim-
ilar cold-induced bradycardia occurs. We have identi-
fied a high expression of calcium cycling proteins in
the cardiac myocyctes of lamnid sharks including the
white shark (Weng et al. 2005). These results suggest
that white sharks have the potential to maintain car-
diac output at cooler temperatures, but the relation of
this capacity to body size remains unknown.
Fishing mortality and management
In this study, 4 juvenile white sharks were captured
by US and Mexican fishermen 6 times. Dewar et al.
(2004) reported that a single juvenile white shark was
captured twice in the SCB. The capture rate of juvenile
white sharks in bottom-set gillnet fisheries in US and
Mexican waters suggests that fishing mortality on
juvenile white sharks in the Eastern Pacific may be
significant and that management actions may be war-
ranted to protect these vulnerable life history stages.
Efforts to reduce fishing mortality will be most effec-
tive if management efforts occur in both US and Mexi-
can waters.
The geographic range of species and individuals is
important in understanding population dynamics
(DeMartini 1993, McNeill & Fairweather 1993, Russ &
Alcala 1996). Futhermore, the fisheries that animals
are likely to encounter, and the required scale of man-
agement actions, changes with ontogeny and season
(Block et al. 2005). In addition to understanding geo-
graphic range, knowing the vertical distribution of
222
Weng et al.: Movement of juvenile white sharks
animals in the water column allows assessment of the
vulnerability of juvenile white sharks to different types
of fishing gear. Vertical habitat data showing a prefer-
ence for the surface mixed layer and upper thermo-
cline indicate that juvenile white sharks may be most
susceptible to fishing gear deployed at these depths.
Furthermore, the diel pattern showing greater vertical
movements during daylight indicates that they are
more likely to be captured in bottom-set gillnets dur-
ing daylight, as noted by Dewar et al. (2004). This
implies that a shift toward nocturnal gillnet effort could
reduce bycatch of juvenile white sharks. In regions
where mixed layer temperatures are cooler than 16°C,
juvenile white sharks rarely make vertical excursions
and thus should be less vulnerable to deeper gear.
Northward movements of larger juveniles may reduce
the risk of encountering bottom set gillnets, as this
gear is presently banned north of Point Conception,
California.
Acknowledgements. This research was supported by grants
from the Monterey Bay Aquarium Foundation and the Office of
Naval Research. We thank the following for assistance with this
study: K. Bates, S. Reid, J. Welsh, M. Ezcurra, T. Athens,
J. Vaudo, D. Topping, M. Blasius, L. Hale, L. Bellquist, K. John-
son, T. Price, K. Anthony, Y. Papastamatiou, C. Williams,
T. Wilmarth, N. Guglielmo, B. Henke, M. Schmidt, C. Espinoza,
C. Spencer, S. Robledo Ruiz, R. Robledo Ornelas, O. Sosa-
Nishizaki, R. Hamilton, C. Farwell, C. Harrold, J. Ganong,
R. Matteson, M. Castleton, S. Teo, A. Boustany, D. Kohrs and
G. Strout.
LITERATURE CITED
Anonymous (1999) Proposal to include Carcharodon car-
charias (Great White Shark) on Appendix I of the Conven-
tion of International Trade in Endangered Species of Wild
Fauna and Flora. Report No. 11.48, CITES, Geneva
Anonymous (2005) World Ocean Atlas. National Oceano-
graphic Data Center, Silver Spring, MD
Anonymous (2006) Astronomical Almanac Online. US Naval
Observatory, Washington, and HM Nautical Almanac
Office, Didcot
Blank J, Morrisette J, Davie P, Block BA (2002) Effects of tem-
perature, epinephrine and Ca
2+
on the hearts of yellowfin
tuna (Thunnus albacares). J Exp Biol 205:18811888
Blank JM, Morrissette JM, Landeira-Fernandez AM, Black-
well SB, Williams TD, Block BA (2004) In situ cardiac
performance of Pacific bluefin tuna hearts in response to
acute temperature change. J Exp Biol 207:881890
Block BA, Teo SLH, Walli A, Boustany A and 5 others (2005)
Electronic tagging and population structure of Atlantic
bluefin tuna. Nature 434:11211127
Bond AB, Stephens JS, Pondella DJ, Allen MJ, Helvey M
(1999) A method for estimating marine habitat values
based on fish guilds, with comparisons between sites in
the Southern California Bight. Bull Mar Sci 64:219242
Bonfil R, Meyer M, Scholl MC, Johnson R and 5 others (2005)
Transoceanic migration, spatial dynamics, and population
linkages of white sharks. Science 310:100103
Boustany AM, Davis SF, Pyle P, Anderson SD, Le Boeuf BJ,
Block BA (2002) Satellite tagging: Expanded niche for
white sharks. Nature 415:3536
Bruce BD (1992) Preliminary observations on the biology of
the white shark Carcharodon carcharias in South Aus-
tralian Waters. Aust J Mar Freshw Res 43:111
Buckley TW, Miller BS (1994) Feeding habits of yellowfin
tuna associated with fish aggregation devices in American
Samoa. Bull Mar Sci 55:445459
Cailliet GM, Natanson LJ, Welden BA, Ebert DA (1985) Pre-
liminary studies on the age and growth of the white shark,
Carcharodon carcharias, using vertebral bands. Mem
South Calif Acad Sci 9:4960
Carey F, Robison B (1981) Daily patterns in the activities of
swordfish, Xiphias gladius, observed by acoustic teleme-
try. Fish Bull 79:277292
Carey FG, Scharold JV (1990) Movements of blue sharks (Pri-
onace glauca) in depth and course. Mar Biol 106:329342
Carey FG, Kanwisher JW, Brazier O, Gabrielson G, Casey JG,
Pratt HLJ (1982) Temperature and activities of a white
shark, Carcharodon carcharias. Copeia 1982:254260
Casey JG, Pratt HL Jr (1985) Distribution of the white shark,
Carcharodon carcharias, in the western North Atlantic.
Mem South Calif Acad Sci 9:214
Cliff G, Dudley SFJ, Jury MR (1996) Catches of white sharks
in KwaZulu-Natal, South Africa and environmental influ-
ences. In: Klimley AP, Ainley DG (eds) Great white sharks:
the biology of Carcharodon carcharias. Academic Press,
San Diego, CA, p 351362
Compagno LJV (1984) Vol. 4 Sharks of the World, Part 1
Hexanchiformes to Lamniformes. United Nations Devel-
opment Programme, Rome
Dagorn L, Bach P, Josse E (2000) Movement patterns of large
bigeye tuna (Thunnus obesus) in the open ocean, deter-
mined using ultrasonic telemetry. Mar Biol 136:361371
DeMartini E (1993) Modeling the potential of fishery reserves
for managing Pacific coral reef fishes. Fish Bull 91:
414427
Dewar H, Domeier M, Nasdy-Lucas N (2004) Insights into
young of the year white sharks (Carcharodon carcharias)
behavior in the Southern California Bight. Environ Biol
Fishes 70:133143
Fergusson IK (1996) Distribution and autecology of the white
shark in the eastern North Atlantic Ocean and the
Mediterranean Sea. In: Klimley AP, Ainley DG (eds) Great
white sharks: the biology of Carcharodon carcharias.
Academic Press, CA, p 321345
Fergusson IK, Compagno LJV, Marks MA (2000) Predation by
white sharks, Carcharodon carcharias (Chondrichthyes:
Lamnidae) upon chelonians, with new records from the
Mediterranean Sea and a first record of the ocean sunfish
Mola mola (Osteichthyes: Molidae) as stomach contents.
Environ Biol Fishes 58:447453
Francis MP (1996) Observations on a pregnant white shark
with a review of reproductive biology. In: Klimley AP,
Ainley DG (eds) Great white sharks: the biology of Car-
charodon carcharias. Academic Press, San Diego, CA,
p 157172
Goldman KJ (1997) Regulation of body temperature in the
white shark, Carcharodon carcharias. J Comp Physiol B
Biochem Syst Environ Physiol 167:423429
Goldman KJ, Anderson SD, McCosker JE, Klimley AP (1996)
Temperature, swimming depth, and movements of a white
shark at the South Farallon Islands, California. In: Klimley
AP, Ainley DG (eds) Great white sharks: the biology of
Carcharodon carcharias. Academic Press, San Diego, CA,
p 111120
Hill RD, Braun MJ (2001) Geolocation by light-level. The next
step: latitude. In: Sibert J, Nielson J (eds) Electronic
223
Mar Ecol Prog Ser 338: 211224, 2007
tagging and tracking in marine fisheries research: meth-
ods and technologies, Vol 1. Kluwer Academic Press, Dor-
drecht, p 315330
Holland K, Brill R, Chang R (1990a) Horizontal and vertical
movements of Pacific blue marlin captured and released
using sportfishing gear. Fish Bull 88:397402
Holland K, Brill R, Chang R (1990b) Horizontal and vertical
movements of yellowfin and bigeye tuna associated with
fish aggregating devices. Fish Bull 88:493507
Holland K, Brill R, Chang R, Sibert J, Fournier D (1992) Phys-
iological and behavioural thermoregulation in bigeye tuna
(Thunnus obesus). Nature 358:410412
Holts D, Bedford D (1993) Horizontal and vertical move-
ments of the shortfin mako shark, Isurus oxyrinchus, in
the southern California bight. Aust J Mar Freshw Res 44:
901909
Inskipp T, Gillett HJ (eds) (2005) Checklist of CITES species
and Annotated CITES Appendices and reservations.
CITES Secretariat, Geneva, Switzerland & UNEP-WCMC,
Cambridge, UK. Available at: www.cites.org/eng/
resources/publications.shtml
Kitagawa T, Nakata H, Kimura S, Itoh T, Tsuji S, Nitta A
(2000) Effect of ambient temperature on the vertical distri-
bution and movement of Pacific bluefin tuna Thunnus
thynnus. Mar Ecol Prog Ser 206:251260
Klimley AP (1985) The areal distribution and autecology of the
white shark, Carcharodon carcharias, off the West Coast of
North America. Mem South Calif Acad Sci 9:1540
Klimley AP, Le Boeuf BJ, Cantara KM, Richert JE, Davis SF,
Van Sommeran S, Kelly JT (2001) The hunting strategy of
white sharks (Carcharodon carcharias) near a seal colony.
Mar Biol 138:617636
Klimley A, Beavers S, Curtis T, Jorgensen S (2002) Move-
ments and swimming behavior of three species of sharks
in La Jolla Canyon, California. Environ Biol Fishes 63:
117135
Kohler NE, Casey JG, Turner PA (1995) Length-weight rela-
tionships for 13 species of sharks from the western North
Atlantic. Fish Bull 93:412418
Korsmeyer KE, Lai NC, Shadwick RE, Graham JB (1997)
Heart rate and stroke volume contributions to cardiac out-
put in swimming yellowfin tuna: response to exercise and
temperature. J Exp Biol 20:19751986
Love MS, Caselle JE, Snook L (2000) Fish assemblages
around seven oil platforms in the Santa Barbara Channel
area. Fish Bull 98:96117
Lowe CG, Goldman KJ (2001) Thermal and bioenergetics of
elasmobranchs: bridging the gap. Environ Biol Fishes 60:
251266
Martin RA (2004) Northerly distribution of white sharks, Car-
charodon carcharias, in the eastern Pacific and relation to
ENSO events. Mar Fish Rev 66:1628
McNeill S, Fairweather P (1993) Single large or several small
marine reserves? An experimental approach with seagrass
fauna. J Biogeogr 20:429440
Mollet HF, Cailliet GM (2002) Comparative population
demography of elasmobranchs using life history tables,
Leslie matrices and stage-based matix models. Mar
Freshw Res 53:503516
Rao RR, Molinari RL, Festa JF (1989) Evolution of the climato-
logical near-surface thermal structure of the tropical
Indian Ocean: 1. Description of mean monthly mixed layer
depth, and sea surface temperature, surface current, and
surface meteorological fields. J Geophys Res C 94:
1080110815
Reintjes JW, King JE (1953) Food of yellowfin tuna in the Cen-
tral Pacific. Fish Bull 54:91110
Ringelberg J, van Gool E (2003) On the combined analysis of
proximate and ultimate aspects in diel vertical migration
(DVM) research. Hydrobiologia 491:8590
Russ G, Alcala A (1996) Do marine reserves export adult fish
biomass? Evidence from Apo Island, central Philippines.
Mar Ecol Prog Ser 132:19
Schaefer KM, Fuller DW (2002) Movements, behavior, and
habitat selection of bigeye tuna (Thunnus obesus) in the
eastern equatorial Pacific, ascertained through archival
tags. Fish Bull 100:765788
Scott MD, Cattanach KL (1998) Diel patterns in aggregations
of pelagic dolphins and tunas in the eastern Pacific. Mar
Mamm Sci 14:401428
Sepulveda CA, Kohin S, Chan C, Vetter R, Graham JB (2004)
Movement patterns, depth preferences, and stomach tem-
peratures of free-swimming juvenile mako sharks, Isurus
oxyrinchus, in the Southern California Bight. Mar Biol 145:
191199
Smith P, Goodman D (1986) Determining fish movements
from an ‘archival’ tag: precision of geographical positions
made from a time series of swimming temperature and
depth. Report No. SWFC-60, NOAA Tech Memo NMFS
SWFC-60, La Jolla, CA
Stevens J, Bonfil R, Dulvy N, Walker P (2000) The effects of
fishing on sharks, rays, and chimaeras (chondrichthyans),
and the implications for marine ecosystems. ICES J Mar
Sci 57:476494
Teo SLH, Boustany A, Blackwell S, Walli A, Weng KC, Block
BA (2004) Validation of geolocation estimates based on
light level and sea surface temperature from electronic
tags. Mar Ecol Prog Ser 283:8198
Tricas TC, McCosker JE (1984) Predatory behavior of the
white shark (Carcharodon carcharias), with notes on its
biology. Proc Cal Acad Sci 43:221238
Uchida S, Toda M, Teshima K, Yano K (1996) Pregnant white
sharks and full-term embryos from Japan. In: Klimley AP,
Ainley DG (eds) Great white sharks: the biology of Car-
charodon carcharias. Academic Press, San Diego, CA,
p 139155
Venrick E, Bograd SJ, Checkley D, Durazo R and 10 others
(2003) The state of the California Current, 20022003:
tropical and subarctic influences vie for dominance. Calif
Coop Ocean Fish Invest Rep 44:2860
Weng KC, Castilho PC, Morrissette JM, Landiera-Fernandez
A and 4 others (2005) Satellite tagging and cardiac
physiology reveal niche expansion in salmon sharks.
Science 310:104106
224
Editorial responsibility: Rory Wilson (Contributing Editor),
Swansea, UK
Submitted: April 8, 2006; Accepted: September 21, 2006
Proofs received from author(s): April 19, 2007
... Figura 2. Diferencias externas entre macho y hembra y útero de Tiburón Blanco (Carcharodon carcharias), mostrando embriones con estómagos distendidos con huevos y dientes en su interior (tomado de Hoyos-Padilla, 2017 California (Dewar et al., 2004;Weng et al., 2007;2012;White et al., 2019;García-Rodríguez et al., en prep.). Cuando los juveniles crecen, obtienen la capacidad de permanecer en aguas más frías (White, 2016) (Domeier, 2012). ...
... Los tiburones del Pacífico Noreste, en particular los de California, Estados Unidos, forman un grupo monofilético separado genéticamente de tiburones de otras regiones (Jorgensen et al., 2010;Díaz-Jaimes et al., 2014) como Sudáfrica, Japón, Australia y Nueva Zelanda (Pardini et al., 2001;Tanaka et al., 2011) (Weng et al., 2007;Oñate-González et al., 2017;White et al., 2019). ...
... La autoridad pesquera (Conapesca) y la pesquera científica (Inapesca), en colaboración con organizaciones de la sociedad civil desde el 2012, han realizado campañas informativas sobre el estatus de protección total del tiburón blanco en las comunidades pesqueras y con las tripulaciones de las embarcaciones mayo- cía-Rodríguez y Sosa-Nishizaki, 2020), lo cual está más relacionado con el comportamiento de la flota pesquera artesanal al utilizar las redes agalleras de fondo que con algún patrón migratorio o temporalidad de la especie. Por otro lado, se sabe que el Tiburón Blanco, durante sus estadios tempranos de vida, utiliza la zona costera desde California y la costa oeste de la península de Baja California para alimentarse y protegerse hasta alcanzar las tallas pertenecientes al estadio subadulto (Weng et al., 2007;2012). Esto sugiere que el Tiburón Blanco en sus primeros estadios de vida es susceptible de ser capturado en la zona costera de California y Baja California durante cualquier temporada del año. ...
... This collaboration to date has resulted in many scientific publications and graduate student projects [13][14][15][16][17][18][19][20][21][22] , each study arising from the analysis of a subset of the overall dataset presented here. The published findings about the biology and ecology of juvenile white sharks initially provided vital insights to the Aquarium's husbandry team that enabled their successful white shark exhibition (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011). ...
... This involves a contracted commercial fishing vessel with purpose-built gears to capture sharks (Fig. 1a) and a research crew to handle animals, monitor health ( Fig. 1b) and attach electronic tags (Fig. 1c). More details on the tagging program and its methodologies are provided elsewhere 14,19,20 . Figure. 2 provides summaries of the deployment schedule, geographic locations, devices, and capture operations. ...
... Higher quality light curves will produce more accurate geolocation estimates. This approach has been used for decades 19 and has been independently validated 20 . www.nature.com/scientificdata ...
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Species occurrence records are vital data streams in marine conservation with a wide range of important applications. From 2001–2020, the Monterey Bay Aquarium led an international research collaboration to understand the life cycle, ecology, and behavior of white sharks ( Carcharodon carcharias ) in the southern California Current. The collaboration was devoted to tagging juveniles with animal-borne sensors, also known as biologging. Here we report the full data records from 59 pop-up archival (PAT) and 20 smart position and temperature transmitting (SPOT) tags that variously recorded pressure, temperature, and light-level data, and computed depth and geolocations for 63 individuals. Whether transmitted or from recovered devices, raw data files from successful deployments ( n = 70) were auto-ingested from the manufacturer into the United States (US) Animal Telemetry Network’s (ATN) Data Assembly Center (DAC). There they have attributed a full suite of metadata, visualized within their public-facing data portal, compiled for permanent archive under the DataONE Research Workspace member node, and are accessible for download from the ATN data portal.
... Figura 2. Diferencias externas entre macho y hembra y útero de Tiburón Blanco (Carcharodon carcharias), mostrando embriones con estómagos distendidos con huevos y dientes en su interior (tomado de Hoyos-Padilla, 2017 California (Dewar et al., 2004;Weng et al., 2007;2012;White et al., 2019;García-Rodríguez et al., en prep.). Cuando los juveniles crecen, obtienen la capacidad de permanecer en aguas más frías (White, 2016) (Domeier, 2012). ...
... Los tiburones del Pacífico Noreste, en particular los de California, Estados Unidos, forman un grupo monofilético separado genéticamente de tiburones de otras regiones (Jorgensen et al., 2010;Díaz-Jaimes et al., 2014) como Sudáfrica, Japón, Australia y Nueva Zelanda (Pardini et al., 2001;Tanaka et al., 2011) (Weng et al., 2007;Oñate-González et al., 2017;White et al., 2019). ...
... La autoridad pesquera (Conapesca) y la pesquera científica (Inapesca), en colaboración con organizaciones de la sociedad civil desde el 2012, han realizado campañas informativas sobre el estatus de protección total del tiburón blanco en las comunidades pesqueras y con las tripulaciones de las embarcaciones mayo- cía-Rodríguez y Sosa-Nishizaki, 2020), lo cual está más relacionado con el comportamiento de la flota pesquera artesanal al utilizar las redes agalleras de fondo que con algún patrón migratorio o temporalidad de la especie. Por otro lado, se sabe que el Tiburón Blanco, durante sus estadios tempranos de vida, utiliza la zona costera desde California y la costa oeste de la península de Baja California para alimentarse y protegerse hasta alcanzar las tallas pertenecientes al estadio subadulto (Weng et al., 2007;2012). Esto sugiere que el Tiburón Blanco en sus primeros estadios de vida es susceptible de ser capturado en la zona costera de California y Baja California durante cualquier temporada del año. ...
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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.
... Larger fish often have a wider vertical habitat than smaller individuals of the same species, in part due to greater physiological tolerances or ontogenetic changes in prey type or breadth (Weng et al. 2007, Afonso & Hazin 2015. We found an inverse relationship of daily maximum depth and fish weight, with smaller individuals diving deeper. ...
... The link between depth and the level of light at night may indicate that tuna track prey which are deeper during the full moon or are trying to avoid predation. Similar links between depth and lunar illumination have been made for other pelagic predators including bigeye tuna, Thunnus obesus (Dagorn et al., 2000), grey reef sharks, Carcharhinus amblyrhynchos (Vianna et al., 2013), and white sharks, Carcharodon carcharias (Weng et al., 2007). ...
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... priscus était inféodé aux zones coralliennes. La dentition de ces requins, dont l'évolution tend vers une augmentation des serrulations des dents, indique un type adaptatif orienté vers des proies d'assez grande taille au sein des poissons téléostéens.Carcharodon hastalis est une espèce plus ubiquiste, généralement océanique, capable de traverser l'Atlantique si l'on en juge par les migrations observées chez son proche parent actuel Carcharodon carcharias (LINNAEUS 1758) [grand requin blanc](Weng et al., 2007). ...
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Cartilaginous fishes (chondrichtyans) of the Serravallian of the Eyre valley (Gironde, France). – Abstract: The first part of this study (published in Fossils n° 42), allowed us to present the historical and geological contexts of the various localities in the Eyre valley (Gironde), of Serravallian age, and to establish in detail the shark fauna. In this second part, we discuss the batoids (rays and skates) as well as the rare chimaeroids present in the different localities. The faunal assemblages of chondrichthyans thus highlighted are then compared with recent faunas as well as with those of other Miocene-age localities. The assemblages are dominated in diversity by carcharhiniformes and in number by lamniformes. An important faunal break with the Langhien is highlighted, confirming the end of the Miocene Climatic Optimum. This resulted in the disappearance or rarefaction of tropical stenothermal species in favour of taxa with a temperate to warm character. Many species of Salles and Mios are close to recent species present in the Gulf of Mexico. Despite the presence of coastal taxa, the faunal assemblage shows a rather oceanic character with the presence of rare bathyal species. Finally, it cannot be ruled out that the Gulf of Salles and Mios served as a nursery for young Carcharodon hastalis and Araloselachus vorax. Keywords: Batoids, Myliobatiformes, Edaphodon, Miocene, Serravallian, Eyre, Leyre, Aquitian Basin.
... In many cases, these movements are associated with prey availability, but links to thermoregulation and bioenergetic efficiency are also documented Sims et al. 2006;Papastamatiou et al. 2015). Over the lunar cycle, movements can be associated with changes in tidal range or moonlight for similar reasons (West and Stevens 2001;Graham et al. 2006;Weng et al. 2007). Likewise, longer-term seasonal variation in solar light levels through increases or decreases in day length (photoperiod) can be important, ultimately through the regulation or entrainment of physiological processes such as reproductive cycles (Carey et al. 1990; Kneebone et al. 2012;Nosal et al. 2013). ...
Article
• Marine Protected Areas (MPAs) are widely used in marine management, but for mobile species understanding the spatio-temporal scale of management measures that is required to deliver conservation benefits depends on a detailed knowledge of species’ movements that is often lacking. This is especially the case for species of skate (Rajidae) for which relatively few movement studies have been conducted. • In Scotland, the Loch Sunart to the Sound of Jura MPA covering 741 km² has been designated for the conservation of the Critically Endangered flapper skate (Dipturus intermedius), but fine-scale movements within this area remain poorly understood. • A passive acoustic telemetry study which coupled acoustic tagging of 42 individuals and a static array of 58 receivers was conducted from March 2016 to June 2017. Using acoustic detection time series, angler capture–recapture data and depth time series from archival tags, fine-scale movements of individuals were investigated. • Overall, 33 of the 42 tagged individuals were detected. Residency, site fidelity and transiency were documented. Residency around receivers, lasting from 3 to more than 12 months, was documented in 16 acoustically detected individuals (48%) and all life-history categories, but was most noticeable among females. Acoustic detections were associated with depth, salinity and season, but there was no evidence that individuals formed close-knit groups in the areas in which they were detected. • Taken together with historical occurrence records of flapper skate, the prevalence and scale of residency documented here suggest that the MPA is sufficiently large to benefit a notable percentage (38 [24–52]%) of skate found in the study area over monthly and seasonal timescales. This result strengthens the case for the use of MPAs to support the conservation of flapper skate and other skate species that display similar movement patterns in areas of high local abundance.
... Shallow water near the coast was known as the preferred nursery ground for juvenile megalodon (Pimiento, et al. 2010). Based on observation of extant sharks, Weng et al. (2007) have reported juvenile sharks have occasionally displayed deeper movements and vertical excursions reaching a depth of 226 m. Shallow water excursions at depth of 26 m were observed mainly during dawn, day, and dusk. ...
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In the Miocene era about 20 million years ago, the South Coast of West Java was a sea and habitat for marine organisms including giant sharks Megalodon measuring about 18 meters long. This study aimed to model the habitat preference of the prehistoric gigantic shark Otodus megalodon population based on the fossil record. From fossil teeth, it revealed that the rock layer where the teeth found was Bentang formation from Miocene era. Many fossils of Megalodon had been unearthed from Bentang formation which is part of the South Coast of West Java. The habitat model was developed using the Sea Level Rise Inundation Tool of ArcGIS to estimate the sea depth and Megalodon’s habitat during the Miocene. The length of the teeth of O. megalodon found was ranged from 13 to 19 cm, indicating the presence of juvenile and adult O. megalodon. Based on the model, in the Miocene era, half of West Java was a sea with a depth ranging from 0 to 200 meters. At that time, it was estimated that juvenile O. megalodon occupied waters with a depth of 0-40 meters with an area of 1365 km2. Meanwhile, adult O. megalodon prefers a depth of 80-160 m and the frequency of habitat use increases at a depth of 200 m. The declining population of O. megalodon is associated with climate change and declining prey populations.
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White sharks ( Carcharodon carcharias ) are the largest shark species to display regional endothermy. This capability likely facilitates exploitation of resources beyond thermal tolerance thresholds of potential sympatric competitors as well as sustained elevated swim speeds, but results in increased metabolic costs of adults, which has been documented in different studies. Little, however, is known of the metabolic requirements in free-swimming juveniles of the species, due to their large size at birth and challenges in measuring their oxygen consumption rates in captivity. We used trilateration of positional data from high resolution acoustic-telemetry to derive swim speeds from speed-over-ground calculations for eighteen free-swimming individual juvenile white sharks, and subsequently estimate associated mass-specific oxygen consumption rates as a proxy for field routine metabolic rates. Resulting estimates of mass-specific field routine metabolic rates (368 mg O 2 kg ⁻¹ h ⁻¹ ± 27 mg O 2 kg ⁻¹ h ⁻¹ [mean ± S.D.]) are markedly lower than those reported in sub-adult and adult white sharks by previous studies. We argue that median cruising speeds while aggregating at nearshore nursery habitats (0.6 m s ⁻¹ [mean ± S.E = 0.59 ± 0.001], 0.3 TL s ⁻¹ ) are likely a feature of behavioral strategies designed to optimize bioenergetic efficiency, by modulating activity rates in response to environmental temperature profiles to buffer heat loss and maintain homeostasis. Such behavioral strategies more closely resemble those exhibited in ectotherm sharks, than mature conspecifics.
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Although evolutionary ecologists agree that proximate and ultimate aspects are two sides of one coin, they are seldom interested in studies on physiological and behavioural mechanisms at the base of ecological phenomena. Nevertheless, these mechanisms are objects of selection and evolved to realise adaptive significances. This paper is a plea to bring both fields closer together, and, by means of an example of Diel Vertical Migration of Daphnia, some proximate and ultimate aspects are discussed. It is argued that light changes, not fish kairomone, is the primary cause for an individual to swim downwards at dawn and upwards at dusk. However, what is called a causal factor might differ when ecosystems or individuals are studied. In addition, causality in ecology is not simple, and has the character of a `set of necessary conditions'. To illustrate the importance of proximate analyses in DVM, two basic response mechanisms are discussed: Photobehaviour system 1 and 2. The physiological character of these systems leads to a fixed type of migration or to a phenotypically induced DVM, respectively. The adaptive significance of the first might be a reduction of the hazardous effects of UV radiation and of the second a lowering of mortality due to visually hunting predators.
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In 1996 we surveyed the fishes living on and around seven offshore oil platforms in the Santa Barbara Channel area. We conducted belt transects at various depths in the midwater and around the bottoms of each platform using the research submersible Delta. The bottom depths of these platforms ranged from 49 to 224 m and the midwater beams ranged from 21 to 196 m. We found that there were several distinct differences in the fish assemblages living in the midwater and bottom habitats around all of the platforms. Both midwater and bottom assemblages were dominated by rockfishes. Platform midwaters were dominated by young-of-the-year (YOY) or juveniles up to two years old. Rockfishes larger than about 18 cm total length were rarely seen in the midwater. The fish assemblages around the bottoms of the platforms were dominated by larger individuals, primarily subadults or adults. Density of all fishes was similar between the bottoms and midwater of any given platform. However, the total biomass was much greater on the bottoms, owing to larger fish living there. There was a consistently greater number of species on the bottom than in the midwater of each platform, likely because of a larger variety of habitat types on the bottom. The fish assemblages also differed among platforms. We found significantly higher densities of young-of-the-year rockfishes around platforms north of Pt. Conception compared with those in the Santa Barbara Channel, probably because the more northerly platforms are located in the more productive waters of the California Current.
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Carcharodon carcharias was studied at Dangerous Reef, South Australia. A single bit action is composed of a uniform sequence of jaw and head movements. Various approach behaviors to baits were documented. Small sharks (<3 m) feed primarily on fish prey, while larger sharks feed on marine mammals, especially pinnipeds. Telemetric studies of white shark thermal biology show that they are warm-bodied, c4-5oC above ambient water temperature. -from Sport Fishery Abstracts
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Two of 5 Pacific fish showed a clear daily cycle of movement between an inshore bank during the day and deep water offshore at night. All of the swordfish responded to light, swimming deep during the day and coming near the surface at night. In the Pacific depth during daylight appeared to be limited to c.100 m by the oxygen-minimum layer, but in well-oxygenated waters of the Atlantic, a midday depth of greater than 600 m was recorded and the fish appeared to follow an isolume. Depth of the Atlantic fish in daylight was related to changes in light caused by variation in water transparency. Vertical movements were associated with temperature changes of as much as 19oC within 2 hr.-from Authors