Geoscience Reference
In-Depth Information
Figure 6.13
Rookery of gentoo penguins. (Credit: Steve Nicol)
island
s north-east coast in order not to be limited by the numbers of whales
available to them.
The pelagic ecosystem of the Southern Ocean has experienced vast changes
over the last 200 years
'
much of it induced by humans. First the massive sub-
Antarctic island populations of fur seals were systematically hunted almost to the
point of extinction. Elephant seals and the great whales were next and some of
their populations are still recovering, whilst others remain precarious. Fish
populations were the next target, and the large populations of the few commercially
attractive species were rapidly reduced to low levels in the 1970s, and they remain
there, leaving only two
-
fish that are currently
harvested commercially at relatively low tonnages. Finally, krill has been harvested
for the last 40 years, although the current level of catch is low (~210 000 tonnes
per year) relative to the estimated biomass, and management measures are now in
fish species (tooth
fish and ice
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