Human Threats to the Little Penguin
Colony
The Little Penguin colony has made its home in the heart of a
densely-populated residential area which is also a popular tourist
destination, only 5km from Australia's busiest shipping port.
There is evidence of penguins being disturbed or injured intentionally
by humans.
There have been incidents of people removing a penguin from the
breakwater with the intention of keeping it as a family pet.
We hope this type of behaviour will disappear with greater awareness
of the colony in the community. Harassing wildlife is illegal, and
a person discovered doing so is liable to a fine under the Wildlife
Act 1975.
Human Residential Threats
With a residential population estimated at 3.2 million, Port Phillip
Bay is Australia's most highly populated catchment. Local population
density and growth, foreshore use, urban planning and development,
all put pressure on the Bay's ecological balance. When it rains,
run-off via stormwater drains contains hydrocarbons and toxic metals
(from cars), high faecal coliform counts (from domestic pets and
wildlife), and rubbish. This all goes into the Bay and affects water
quality.
Threats from Tourism & Recreation
Recreational fishing and boating, jetskis, yachting, strolling,
and walking the dog present threats to penguins. These threats include
fishing line, hooks and other tackle, litter, small oil spills,
and harassment by humans or dogs. The recreational fishing catch
is thought to equal the commercial catch, which puts pressure on
fish stocks. Also, poorly managed tourism operations may disturb
penguins.
Threats from Commercial Activities
Commercial shipping-related threats include exotic species introductions
with ballast water, oil/chemical spills, and toxic metals from marine
paints. Prior to the pilchard population crash of 1995 unrestricted
commercial fishing for pet food put pressure on fish stocks on which
penguins and other seabirds depend for survival.
Litter
Another danger to penguins is litter discarded on beaches, or
from boats, or washed into Port Phillip Bay down stormwater drains.
- Volunteers found several penguins trapped in the plastic yoke
that holds together six beer cans
- Plastic bags can suffocate marine animals
- Fishing line, hooks and sinkers are other threats
- Penguins have been found with fishing line so tightly wound
around their leg having caused their foot to eventually drop off,
reducing their chance of survival
- One penguin was discovered to have died of lead poisoning from
swallowing a sinker
- Expanded polystyrene is also a threat because when eaten it
stays in the stomach undigested. The penguin no longer thinks
it is hungry
What Is Being Done About It?
No such incident has been recorded since 1993, thanks to the local
Port Phillip Council installing litter traps on local stormwater
drains, and the education of local anglers and visitors to the Breakwater.
In addition, plastics manufacturers have developed a type of plastic
for yokes that biodegrade if subjected to sufficient sunlight.
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Animal Threats - Introduced Pests
Exotic (non-native) creatures carried in the ballast water tanks
of international ships can and have established successful populations
in the Bay, as they have no natural predators. These creatures compete
for food with native fauna, threatening their survival. The result
can be change to the food web, ecosystem and ultimately survival
of higher order animals, such as penguins.
Animal Threats - Introduced Predators
Exotic introductions, such as foxes, dogs and cats are potential
penguin predators. Foxes and cats inhabit the foreshore only 600m
away, however there has been no evidence as yet of foxes and cats
coming onto the breakwater.
Dogs are frequently walked along the breakwater, often unleashed.
Dogs have been known to kill penguins in a single bite and then
catch another.
Animal Threats - Native Predators
The Rakali (or native water rat) is known to take bird eggs elsewhere,
however they have never been recorded in penguin nests in St Kilda.
Researchers put this down to the local abundance of other Rakali
prey - mussels and crabs, and also the ferocious striking ability
of adult penguins.
Pacific Gulls, Kelp Gulls, Harriers and Sea Eagles prey on penguin
chicks elsewhere. Only Pacific Gulls are present in St Kilda, but
in relatively small numbers.
The Tiger Snake also will take penguin eggs and chicks, however
this species is rarely seen locally, and has never been sighted
on the breakwater.
Environment - Pilchard Crashes
Two large-scale pilchard crashes (or die-offs) have occurred in
Victoria in recent years. Local marine scientists have found no
explanation for either crash. The first occurred between March and
June, 1995, which was after the pilchards had spawned, and the second
was in November-December 1998. It is thought that a significant
decline in the numbers of penguins at Phillip Island and at St Kilda
in 1995 was a result of the pilchard crash in May 1995.
Environment - Oil & Chemical Pollution
Australia's busiest seaport is only kilometres away from the breakwater,
and Melbourne's international container shipping traffic and motorised
recreational craft travel through one of the penguins' favourite
feeding zones.
Accidents involving large-scale spillage of petroleum or other
toxic products from ships, boats and shore-based industrial complexes
or trucks could have a major impact on the colony. Despite this
there has never been a large oil or chemical spill in the Bay.
Minor spills are not uncommon in Melbourne's commercial ports and
recreational harbours. Even minor diesel spills from recreational
craft - if they are washed against the breakwater's rocks - can
make it dangerous for penguins to return to their nests.
There are also areas in the Bay where high concentrations of hydrocarbons
and toxic metals have been recorded.
No major oil or chemical spill has ever been recorded in the Bay.
The Management Plan provides for the control of spills through state
oil spill and state disaster (DISPLAN) plans.
Port Phillip Bay Shipping Channel Deepening Proposal
A current issue of great importance is the Port Phillip Bay shipping
channel deepening proposal, which, if it goes ahead, will have
a significant impact on the Little Penguin colony at St Kilda breakwater. |
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