Activity, Diet and Habitat
The Tasmanian Giant Freshwater Lobster are
slow growing, slow to colonise new areas and have a low reproductive
rate. With a diet of
mainly decaying wood and leaves, fish,
rotting flesh and detritus are also eaten. While little is known of
their dispersal patterns individuals have been recorded moving 500m
in 24 hours, with movements over land
also being recorded.
They have been recorded as most active during early autumn
and summer when water temperatures are higher.
By nature, the Tasmanian Giant Freshwater
Lobster is shy and secretive. With the ideal habitat including
intact stream catchment of several stream sizes, including rivulets
and small headwaters. These should flow and meander through a
relatively undisturbed well vegetated catchment containing snags,
pools and undercut, but not eroding, banks. The water
temperature should seldom exceed 18°C,
have a high oxygen content and be clear of
The females of the specie
breed every two years with mating and spawning occurring between March
and April (Autumn). The female carries the eggs under her tail over
winter until they hatch in late December-January (Summer). Hatchlings
stay attached until late February when they measure about 6 mm CPL
(Carapace (Body/Head) Length). The young then moult several times a
year, but this becomes less frequent as they get older.
lobsters have been located in shallow faster flowing areas known as
riffle zones. It is suspected they migrate into smaller stream zones
including semi-permanent creeks. It is in these areas that they are
safer from many predators such as larger fish (blackfish, trout) and
platypus, which struggle to swim in the very shallow sections. The
juveniles find cover amongst the cobble rocks and woody debris and
remain in this area until large enough to move into the deeper areas
known as runs. Runs are deeper flowing straight sections of a catchment.
Many sub adult (<100mm CPL) have been located in these areas. It is
suspected that these sub adults are not large enough to enter the domain
of the adult lobsters, the deeper pools.
Adults take refuge in still, deep pools, which are sheltered and well
shaded beneath submerged and decaying timber and can live in larger
numbers (up to 20 individuals) in one large pool. Although sometimes
aggressive, lobsters appear to tolerate one another in these pools. It
is estimated that lobsters may live beyond 40 years.
Female lobsters mature after about 14 years, weighing about 500g with a carapace
(head shell) length (CPL) of 120mm. Males mature more quickly at around 300g and
approximately 76mm CPL in about 9 years.
Measuring a juvenile.
Further information available on the
Tasmania's Giant Fresh Water Lobster
from the Inland Fisheries Service.