First record of an attack by a cookiecutter shark

First record of an attack by a cookiecutter shark
(Isistius brasiliensis) on a white shark
(Carcharodon carcharias)
By Mauricio Hoyos-Padilla, Yannis P. Papastamatiou*, John
O’Sullivan, and Christopher G. Lowe
Abstract
Cookiecutter sharks (Isistius brasiliensis) are known to attack a wide array of large animals
including pelagic fishes, cetaceans, and pinnipeds. Here we add another top predator, the white
shark (Carcharodon carcharias), to the list of potential victims. A sub-adult male white shark
off of Guadelupe Island, Mexico was observed with a fresh cookiecutter shark bite next to its
mouth, as well as a second crescent shaped scar. A sub-adult male white shark was tracked in the
same location, and showed diel changes in depth, with the shark occupying shallow water (<50
m) at night, which may be when white sharks overlap with the vertical distribution of
cookiecutter sharks. This further indicates that the majority of co-occurring marine top predators
can be targeted by cookiecutter sharks.
*Corresponding author. E-mail: [email protected]
Pacific Science, vol. 67, no. 1
August 2, 2012 (Early view) Introduction
Top predators, by definition, have few to no natural predators with the exception of
parasites. However, there can be notable exceptions, including specially adapted smaller
predators, which are able to non-lethally prey on animals much larger than themselves (in
essence becoming ectoparasites). In marine systems, the squaloid cookiecutter shark (Isistius
brasiliensis, Quoy and Gaimard 1824), has occupied this niche, by being able to forage on
marine predators over 10 times their own body length. I. brasiliensis are small sharks (maximum
total length 56 cm), and are able to prey on larger animals using their unique feeding strategies,
dentition, tongue and mouth morphology, to scoop out a hemispherical plug of flesh from their
prey (Jones 1971, Shirai and Nakaya 1992). As such, I. brasiliensis are known to attack and bite
a wide variety of large animals including seals, whales, orcas, porpoises, pelagic fishes, sharks,
and recently even a human swimmer (Van utrecht 1959, Le Boeuf et al. 1987, Yamaguchi and
Nakaya 1997, Papastamatiou et al. 2010, Dwyer and Visser 2011, Honebrink et al. 2011). I.
brasiliensis are found throughout tropical and sub-tropical waters and also extend into cooler
waters as far south as New Zealand (Compagno et al. 2005, Dwyer and Visser 2011). Here, the
list of apex predators potentially targeted by I. brasiliensis is expanded to include the sub-adult
white shark (Carcharodon carcharias).
MATERIALS AND METHODS
The observation occurred off Isla Guadalupe (29°00'N, 118°15'30"W), located 240 km
west of Baja California, Mexico (Fig. 1). The island lies within the California Current, with an
average sea surface temperature of 18°C, ranging from 15° C in February–March, and increasing
to 21° C - 22° C in September–October. Water depths of up to 3,600 m surround the island.
There is little shelf habitat around the island with exception of the southern tip were a 4 km wide
and ~200 m deep shelf is found between Isla Guadalupe, Isla Zapato (Outer Islet) and Isla Toro
2
(Inner Islet). Male white sharks arrive at Guadalupe Island as early as July and females in
September, with peak abundance at the site occurring from August–December (Domeier and
Nasby 2007). During this period, cage diving operations operate in front of Playa Norte, on the
northeast side of the island (Figure 1). Chum is used to bait in white sharks, after which a surface
floating cage containing tourist divers is dropped in the water. Cookiecutter shark bites were
studied from photographs of a white shark seen at the cage diving site (see below). We used the
classification scheme of Dwyer and Visser (2011), where bites were listed as ASSUMED (bite
looks similar in shape to published photos of cookiecutter bites) or SUSPECTED (bite looks
similar in shape but with less definition and may be well healed), and then classified by state
(fresh or healed), depth and shape (OVAL or CRESCENT).
A sub-adult male white shark, attracted to the cage operation, was continuously tracked
for 24 h from November 10-11 2006. The shark was attracted towards the cage and a pole spear
was used to tag the animal with a V16 depth/temperature transmitter (Vemco ltd., Nova Scotia,
Canada, 69 kHz). A directional hydrophone and VR100 receiver were used to track the animal
from the vessel, while simultaneously recording swimming depth and water temperature. A GPS
location was obtained every 1 minute.
RESULTS
Two pictures taken on 25 August 2010 showed a 3 m male, C. carcharias with a fresh
ASSUMED bite (OPEN CRATER, OVAL), and a SUSPECTED scar (SMOOTH SCAR,
CRESCENT) inflicted by an I. brasiliensis (Fig. 2). Based on the life history categorization of
Bruce and Bradford (2012), we determined that the white shark was a sub-adult (i.e. not yet
mature). The bite wound was located on the left side of the shark´s head, close to and just lateral
of the corner of the mouth, below the beginning of the dark grey dorsal surface, while the
crescent shaped scar was just posterior to the open bite (Fig. 2). In addition, there was no
3
indication of a centered hole within the crater indicative of a possible large hook exit wound (e.g.
from a fishing hook).
The acoustically tracked shark displayed continuous bounce dives with an overall diel
change in depth. During the day bounce dives as deep as 100 m were performed, but the
nighttime distribution was shallower, with most dives < 50 m (Fig. 3). The white shark remained
in a small area (0.29 km2), with water depths of 20-100 m, close to shore in the northeast part of
the island during the entire track (Hoyos-Padilla 2009).
DISCUSSION
To the best of our knowledge, this is the first record of a white shark being preyed upon
by a cookiecutter shark. Records indicate Isistius brasiliensis as the only species found in eastern
Pacific waters, although sampling and surveying in these areas may be limited (Compagno et al.
2005). Therefore, the designation of the attacking shark as I. brasiliensis should be treated with
some caution.
I. brasiliensis have been found from the surface down to 3500 m and are thought to
perform diel vertical migrations, moving into surface waters at night (Le Boeuf et al. 1987,
Papastamatiou et al. 2010). Based on the data from the individual white shark actively tracked,
and others, the white shark would have shared the known depth range of cookiecutter sharks
during the night time period (Hoyos-Padilla 2009). Evidence of I. brasiliensis predation rate on
C. carcharias is likely rare, as no other individual white sharks in the Guadalupe Photo-ID
catalog (considered the largest of its kind, 116 white sharks identified so far) had scars (Domeier
and Nasby-Lucas 2007). It has been hypothesized that I. brasiliensis may attract upward looking
predators using their ventral photophores and a collar of pigmented cells posterior to the head, as
a lure (Widder 1998). The presence of the bite and the scar close to the mouth of the C.
carcharias could add credence to the hypothesis. Furthermore, the similar size of the scar and the
4
bite may indicate that the same cookiecutter shark attacked the white shark twice, with the first
strike being unsuccessful. Alternatively, the white shark may have been bitten while it was itself
consuming prey on the surface. At Guadalupe Island, fresh crater wounds have been observed on
Guadalupe fur seals, Arctocephalus townsendi (Gallo-Reynoso and Figueroa-Carenza 1992).
Little is known of the cetacean population dynamics of Guadalupe Island, although at least 18
species (four Mysticetes and 14 Odontocetes) frequent the area (Gallo-Reynoso et al. 2005). In
other locations, cookiecutter bites have been reported on beaked whales, sperm whales, several
species of porpoises and most of the baleen whales (Mackintosh and Wheeler 1929; Van Utrecht
1959). Such prey may either represent less of a threat to I. brasiliensis or may provide higher
caloric content due to the higher blubber composition of marine mammals. The only recorded
predation on a cookiecutter shark was a single individual found in a tuna stomach (Isouchi 1970).
Tuna stomach contents are sampled frequently enough to detect rare predation events, which is
not possible for apex predators such as white sharks or orcas. Consequently, it is unknown how
frequently cookiecutters may fall victim while attacking other large predators. Along with
observations of bites on orcas (Dwyer and Visser 2011), two of the largest marine predators are
now known to be I. brasiliensis victims.
ACKNOWLEDGEMENTS
We want to thank The WWF-TELCEL Alliance for sponsoring the 2009 expedition, and Gerardo
del Villar of dive encounters, who kindly donated the pictures of the White Shark with the
bites/scars. Fieldwork was greatly facilitated through courtesies extended to us by personnel of
SEMAR, CONANP, SEGOB, GECI, local fishermen from Cooperativa de Abuloneros y
Langosteros, Horizon Charters, Islander Charters, Nautilus Explorer, Sea Scape, Solmar V and
Andrea Lynn. This research was conducted under the following Scientific Research Permits:
5
SEMARNAT No. SGPA/DGVS/00676/09; CONANP No. F00. RNO. RBIG.-121/09; and
SEGOB No. DICOPPU/211/1462/09.
6
Figure 1. The location of Guadalupe Island. Shadowed areas show the location of submarine
canyons on the east coast of the island. The star marks the location where the white shark was
observed.
7
Figure 2. Two pictures of the white shark with bite and scar inflicted by a Cookiecutter Shark on
the left side of the head. Posterior to the oval shaped bite is a SUSPECTED crescent shaped scar.
The bite and scar are enlarged in B, and the arrow points to the crescent shaped scar.
8
Figure 3. Swimming behavior of a sub adult white shark in Guadalupe Island as determined by
acoustic tracking. Nighttime indicated by stippling.
9
LITERATURE CITED
Bruce, B.D., and R. Bradford. 2012. Habitat use and spatial dynamics of juvenile white sharks,
Carcharodon carcharias, in Eastern Australia. In Global perspectives on the biology and
life history of the white shark (Domeier, M. ed). Boca Raton, FL. CRC Press
Domeier, M., and N. Nasby-Lucas. 2007. Annual re-sightings of photographically identified
white sharks (Carcharodon carcharias) at an eastern Pacific aggregation site (Guadalupe
Island, Mexico) Mar. Biol. 150: 977–984
Dwyer, S.L., and I.N. Visser. 2011. Cookie cutter shark (Isistius sp.) bites on cetaceans, with
particular reference to killer whales (orca, Orcinus orca). Aquat. Mamm. 37: 111-138
Compagno, L., M. Dando, and S. Fowler. 2005. Sharks of the world. Princeton University Press,
Princeton.
Gallo-Reynoso, J.P., and A.L. Figueroa-Carenza. 1992. A cookiecutter shark wound on a
Guadalupe fur seal male. Mar. Mamm. Sci. 8: 428-430
Gallo-Reynoso, J.P., B.J. Le Boeuf, A.L. Figueroa, and M.O. Maravilla. 2005. .Los pinnípedos
de Isla Guadalupe. En: K. Santos-del-Prado y E. Peters (comps.). Isla Guadalupe. Hacia
su restauración y conservación. Instituto Nacional de Ecología, México, D. F. pp. 171201.
Honebrink, R., R. Buch, P. Galpin, and G.H. Burgess. 2011. First documented attack on a live
human by a cookiecutter shark (squaliformes, Dalatiidae: Isistius sp.). Pac. Sci. 65: 365374
Hoyos-Padilla, M. E. 2009. Patrones de movimiento del tiburón blanco (Carcharodon
carcharias) en Isla Guadalupe, México. Ph.D. dissertation. Centro Interdisciplinario de
Ciencias Marinas (CICIMAR). Instituto Politécnico Nacional. La Paz, B.C.S. 149 p.
10
Isouchi, T. 1970. A cigar shark, Isistius brasiliensis from tropical water of the eastern Pacific.
Jap. J. Ichthyol. 17: 124-125
Jones, E.C. 1971. Isistius brasiliensis, a squaloid shark, the probable cause of crater wounds on
fishes and cetaceans. Fish. Bull. U.S. 69: 791-798
Le Boeuf, B.J., J.E. McCosker, and J. Hewitt. 1987. Crater wounds on northern elephant seals:
the Cookiecutter Shark strikes again. Fish. Bull. 85: 387–392
Mackintosh, N. A., and J.F.G. Wheeler. 1929. Southern blue and fin whales. Disc. Rep. 1: 257540
Papastamatiou, Y. P., B. M. Wetherbee, J. O'Sullivan, G. D. Goodmanlowe, and C. G. Lowe.
2010. Foraging ecology of cookiecutter sharks (Isistius brasiliensis) on pelagic fishes in
Hawaii, inferred from prey bite wounds. Environ. Biol. Fish. 88: 361–368
Shirai, S., and K. Nakaya. 1992. Functional morphology of feeding apparatus of the cookiecutter
shark, Isistius brasiliensis, (Elasmobranchii, Dalatiinae). Zool. Sci. 9: 811-821
Van utrecht, W. L. 1959.Wounds and scars on the skin of the common porpoise Phocaena
phocaena (L.). Mamm. 23: 100-122.
Widder, E.A. 1998. A predatory use of counter-illumination by the squaloid shark, Isistius
brasiliensis. Environ. Biol. Fish. 53: 267–273.
Yamaguchi, R., and K. Nakaya. 1997. Fukuoka megamouth, a probable victim of the
cookiecutter shark. In Biology of the megamouth shark (Yano, K., J.F. Morrissey, Y.
Yabumoto, and K. Kakaya, eds), p. 171. Tokyo, Tokai University Press
11