Research
White sharks
Threats, status and conservation
White sharks are naturally low in abundance, have low reproductive potential,
and are believed to have low natural mortality. Female white sharks do
not reproduce until they are very large, produce only a few young each
time, and probably do not breed every year. This is a very different strategy
to most fish that may spawn millions of eggs each year. These characteristics
mean that white shark populations are vulnerable to human interference
and recover very slowly if reduced in abundance.
Fisheries
White sharks are not targeted in commercial fisheries, but form a component
of bycatch in several fisheries worldwide, including longline, gillnet,
trawl and handline/rod-reel fisheries. The species is also known to interact
with finfish aquaculture cages. Catch statistics for most commercial fisheries
are poorly recorded.
White sharks are (or have been) a target species in sports/game fisheries
and are sometimes targeted due to either their nuisance value, in retribution
for shark attack, or for the high price paid for fins, jaws and teeth
on the international market.
They are a target species in Australian and South African shark control
programs. In some cases, however, these programs now release live sharks.
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Population status
No reliable estimates exist of the number of white sharks in Australian
waters. The available information is complicated by a variety of factors
including year-to-year variations in the rate of capture, and sightings
of white sharks that are probably not related to population size. Although
some of the data are ambiguous, most suggest a decline in abundance, but
it is not possible to estimate either the magnitude or the implications
of this suspected decline.
Declining catch rates of juveniles have been recorded in shark control
programs in South Africa and NSW, with a decline in mean size reported
in the latter study. Catches in a similar program in southern Queensland
have not shown strong evidence of a decline. Significant declines in the
ratio of white sharks to other species of sharks taken by gamefishers
have been reported in the Mid-Atlantic Bight and off eastern Australia,
although these may not take into account changes in targeting behaviour
by fishers.
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Conservation measures
White sharks were listed as 'Vulnerable' in Australian Commonwealth
waters in 1997 and 'Vulnerable' (A1cd + 2cd) on the 2000 IUCN Red List
of Threatened Species. They are fully protected in Australia, California,
Florida, South Africa, Malta, Namibia and the Maldives.
White sharks were listed on Appendix I of the Convention on Migratory
Species (CMS) in 2002 and on Appendix II of the Convention on International
Trade in Endangered Species in October 2004. The white shark section of
the 2002 'Conservation overview and action plan for Australian threatened
and potentially threatened marine and estuarine fishes' is available at
the Department
of Environment and Heritage website.
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