© Photograph by Dick Williams
Copyright Australian Antarctic Division.
There are two species of Toothfish: the Antarctic
Toothfish (Dissostichus mawsoni) and the Patagonian
Toothfish (Dissostichus eleginoides). They are very
similar in appearance and habits but the Antarctic Toothfish
is found in the high latitude region close to the Antarctic continent
whereas the Patagonian Toothfish is found in sub-Antarctic waters
on shelves around islands and submarine banks.
Toothfish are bottom-living, in depths
of 300m to 2500m, but move off the bottom on occasion to feed.
The Antarctic Toothfish has antifreeze proteins
in its tissues and blood because the seawater is below the normal
freezing point of tissue. The Patagonian Toothfish does not have
these proteins because it lives in warmer water.
Toothfish eggs and larvae are pelagic (free swimming/floating
near the sea surface) and the larvae feed on zooplankton.
Toothfish eat small fish and squid in midwater
and a range of fish, crabs, prawns etc. on the bottom.
Toothfish reach sexual maturity (can produce eggs
and sperm) when they are between 70cm and 95cm long. At this
size the fish are between 8 and 10 years old.
The maximum size of Toothfish is 2.2m in length
and about 120kg in weight. The maximum recorded age is about
45 years.
Both species of Toothfish are known to be eaten
by sperm whales and elephant seals, but the extent of this is
unknown. The fish are usually too large to be eaten by other
types of predators.
Commercial fishing of the Patagonian Toothfish
is managed by CCAMLR (the Commission for the Conservation of
Antarctic and Marine Living Resources) around most of the sub-Antarctic
Islands, but not off the southern coast of South America. Long-lining
(the most common fishing method) causes serious problems in that
it catches large numbers of albatrosses and other seabirds. Fishing
by trawling does not usually harm seabirds but tends to catch
fish in the smaller size range. In some circumstances trawls
can damage the seabed. There is currently only a very small fishery
for the Antarctic Toothfish, mostly because it occurs far south
in waters where sea ice occurs.
Illegal fishing of the Patagonian Toothfish has
become a very serious problem in recent years. In 1997/98 about
11 000 tonnes were caught legally in the CCAMLR area, but the
illegal catch was estimated to be 32 000 tonnes. In some areas
the illegal activities have reduced the stocks of Toothfish markedly.
Several nations have arrested a number of boats fishing illegally.
Constable, A., Williams R., de
la Mare, W.K. and Slip, D. (1997). Escapement of Elephant Seal
prey in the Heard island fishery for Dissostichus eleginoides.
CCAMLR Working Group on Ecosystem Monitoring & Management
paper WG-EGMM-97/42
de la Mare, W.K. and Williams,
R. (1996) Abundance of Patagonian Toothfish at Macquarie Island
estimated from tagging studies during the 1995-96 fishing season.
In: (Ed.). CCAMLR Document WG-FSA-96/39
de la Mare, W.K. and Williams,
R. (1996) Estimates of absolute recruitment for Patagonian Toothfish
(Dissostichus eleginoides) around Heard Island. In: (Ed.).
CCAMLR Document WG-FSA-96/38
Reilly, A., Ward, R. and Williams,
R. (1998). Preliminary results of investigations into the stock
structure of Patagonian Toothfish (Dissostichus eleginoides)
around Macquarie Island. CCAMLR Document WG-FSA-98/39
Report of the fourteenth meeting
of the Scientific Committee Sc-CCAMLR (1995), Report of the workshop
on methods for the assessment of Dissostichus eleginoides
pp.388-413, Sc-CCAMLR XIV
Williams, R. and de la Mare, W.K.
(1995) Fish distribution and biomass in the Heard Island zone
(Division 58.5.2). CCAMLR Science 2: 1-20
Williams, R. (1995) Seabird interactions
with trawling operations at Macquarie Island. CCAMLR Document
SC-CAMLR-XIV/BG/6
