White sharks eat a variety of finfish, other sharks, seals,
sea lions, dolphins, whales, squid, crustaceans and sea birds.
Juveniles (smaller than 2.7 m) feed mainly on fish, other
sharks and rays, whereas larger sharks (3.4 m+) feed on marine
mammals. The change in diet is believed to be linked to the
reduced agility of larger sharks.
Contrary to popular belief, human beings are not prey
items for these supreme predators. The majority of white
shark attacks are non-fatal and are widely believed to be
cases of mistaken identity. A human paddling on the surface
might be mistaken for an injured prey animal or seal. It’s
also helpful to keep shark attacks in perspective; statistics
suggest that beach-loving Australians are more likely to die
from drowning or skin cancer than from encountering a white
shark. Bees, cows, falling furniture and road accidents also kill
considerably more Australians annually than white sharks do.
Increased media coverage creates the perception that shark
numbers and shark attacks are on the rise; however, there is
no evidence of increasing shark numbers in Australian waters
and the perception is skewed by the fact that as the human
population grows, more people are entering the water, and
thus encounters occur more frequently.
Demand for fins
The current scale of the threat to global shark populations is
enormous. According to the IUCN Shark Specialist Group, one
quarter of chondrichthyan fishes (sharks, rays, and chimaeras) are
threatened due to targeted and incidental fishing. Shark fishing
is a lucrative practice, with fishers targeting sharks to meet the
demand for shark fins in Asian markets. High economic incentives
coupled with the expense of enforcing restrictions over vast
geographic areas has resulted in globally unregulated shark fishing
industries. The unprecedented pressure from fisheries highlights
the need for the public image of sharks to evolve if we are to have
any hope of warding off extinctions.
As important apex predators, sharks fundamentally influence the
structure and function of marine ecosystems. Fewer sharks usually
means more mesopredators (for example large fish and rays) and/
or herbivores in mid-trophic levels. In turn, the increase of mid-
level predators affects species at lower trophic levels (such as
small fish and crustaceans). Thus, changes to the upper levels of
the food chain ‘cascade’ down, influencing the ecosystem in ways
that can be difficult to predict. Such cascades from over-exploiting
sharks have been recorded in several marine ecosystems.
So, what can we do to make people care more about sharks
and the marine ecosystems that depend upon them? Many
researchers believe that exposing tourists to wildlife within its
natural environment can contribute to conservation – enhancing
environmental knowledge, changing attitudes, and altering
behaviour through interpretive messaging and meaningful first-
hand experiences. Is this possible with sharks? Can shark-based
tourism engender a positive conservation ethic in participants,
or are tourists motivated only by adrenalin-pumping adventure
and the opportunity for some tall tales of their own? These
questions led me to the Neptune Islands and aboard Australia’s
white shark cage-dive tours to conduct my PhD research.Tourism with teeth
Shark species undoubtedly capture the human imagination.
Shark-based tourism has experienced dramatic growth over the
past two decades. An estimated 590,000 tourists worldwide now
participate in shark-watching activities annually, interacting
with a range of shark species. Thriving cage-dive industries exist
in places where white sharks can be reliably observed, which
includes parts of Mexico, the Californian coast, South Africa,
New Zealand and Australia. Cage-dive tours have been operating
off the Neptune Islands, SA, since the late 1970s. Currently,
there are three licensed operators, with two offering daytrips of
approximately 12 hours in duration and one offering multi-dayA white shark leaps from the water, a
behaviour known as breaching, to catch
a seal. Large sharks lead a high-energy
lifestyle that may necessitate a high-fat diet,
resulting in increased seal predation for
adult white sharks. Individuals might even
switch between periods of feeding around
seal colonies and other predatory strategies
that incorporate finfish and other sharks.
Photo: LWP Kommunikacio [CC]
Photo: Calypso Star ChartersWildlife Australia | 7