Australia Yearbook - 2001

600 Year Book Australia 2001
One of the noticable impacts of increasing sea
temperatures is the bleaching of the world’s coral
reefs. Known for their natural beauty, biological
diversity and high productivity, these represent a
crucial source of income for fisheries, tourism
and the emerging market of biotechnology. The
bleaching of the world’s corals will severely
impact on these sources of income. Bleaching
occurs when the symbiotic algae are expelled
from the coral due to stress induced by rising sea
temperatures. Sea temperatures in the tropics
have increased by almost one degree celcius in
the last 100 years. The last major bleaching
episode occurred in 1998, when 87% of inshore
reefs of the Great Barrier Reef were affected by
bleaching to some extent (Berkelmans and Oliver
1999). With corals currently living at the upper
limit of their thermal tolerance, an increase by
one to two degrees celcius over the next century
will see an increase in bleaching episodes and
more deaths of the world’s corals.
Whaling
Many of the great whales are now listed as
threatened species and are either endangered,
vulnerable or conservation dependent. The
decimation of whale numbers was initially due to
unregulated whaling during the early part of the
20th century. Attempts to regulate the whaling
industry started in 1925 and were ineffective until
the mid 1960s when a number of whale species
were listed as protected. By this stage, species
such as the Northern Right whale and the Blue
whale were hunted close to extinction. Currently,
the serious threats to whales include marine
pollution, habitat degradation, bycatch from
fisheries and illegal fishing, noise pollution, global
climate change, accidents and disturbances from
shipping, boating and tour operators.
The inability of certain whale species to recover
from declining population numbers is related to
their biology. Whales are long lived, with some
species living up to 90 years. Large whales may
only reproduce every three to four years. Limited
data are available on numbers of whales within
each species prior to exploitation by commercial
whaling. Table 14.30 provides some estimates on
whale populations in the Southern hemisphere
and current status under the Environment
Protection Conservation and Biodiversity Act
1999. Most whale species are protected due to
the limited numbers that remain.
Australia’s Antarctic oceans are home to many
migratory whale species that spend the summer
months in the Antarctic waters and move further
north during the winter to give birth or for
mating. Whale sanctuaries have been set up to
protect whale populations from further decline.
These sanctuaries also assist in non-lethal
methods of research into whale species. The
Southern Ocean Whale Sanctuary, endorsed by
the International Whaling Commission (IWC) in
1994, covers an area of around 50 million square
kilometres. Combined with the Indian Ocean
Sanctuary (endorsed in 1992), these protected
areas cover around one-third of the world’s
oceans. Australia has proposed another whale
sanctuary for the South Pacific Ocean, which
would protect whales’ migratory patterns along
the east coast of Australia. This current proposal
has faced opposition from Japan, which still
participates in whaling for scientific research.
14.30 GREAT WHALES IN THE SOUTHERN HEMISPHERE
Pre-exploitation population
Current population
Species
Status(a)
no.
no.
Southern right whale endangered not known 1,500 to 4,000
Blue whale endangered 250,000 200 to 1,000
Pygmy blue whale data deficient not known ~ few thousand
Fin whale vulnerable 300,000 to 1,650,000 ~24,000
Sei whale vulnerable not known ~40,000 (uncertain)
Humpback whale vulnerable not known 12,000
Minke whale near threatened around post whaling numbers 500,000 to 1,100,000
(a) Status from Environment Protection Conservation and Biodiversity Act 1999 with the exception of pygmy blue and minke
whales (World Wildlife Fund International).
Source: Derived from WMF (International) website, Environment Protection Conservation and Biodiversity Act 1999.