SPOTTING THE DIFFERENCE BETWEEN CORAL TROUT
5 July 2004
While any Queensland fisher worth their spots can tell you what a coral
trout looks like, the difference between some species of coral trout can
be hard to recognise. CRC Reef’s Fishing and Fisheries team have
discovered that while they may be hard to tell apart, blue-spot trout
and other types of coral trout have vital differences, which can be seen
in a new CRC Reef poster.
The blue-spot trout, Plectropomus laevis, is also known as
the tiger trout, the Chinese footballer trout and the oceanic trout, and
its identification has caused much confusion. Since December last year,
changes to the Coral Reef Fin Fish Management Plan have meant that the
legal size for blue-spot trout is different from other species of coral
trout.
The regulations from the Queensland Department of Primary Industries
and Fisheries allow fishers to catch blue-spot trout between the 50 and
80cm in length, in contrast to the minimum legal size of 38cm that applies
to other species of coral trout.
However, the effectiveness of the new regulations relies on fishers being
able to distinguish the blue-spot from other coral trout species.
“The blue-spot grows more quickly than other species of coral trout,”
according to CRC Reef researcher Mr Gary Carlos, from James Cook University.
“It can grow to almost twice the size of the common coral trout,
although its life-span of up to 15 years is about the same.”
“Because of their different growth rates, blue-spot trout become
sexually mature at a larger size than other coral trout. They also change
from female to male as they grow older. We found that at 38cm, which is
the minimum legal size for other coral trout, only a few blue-spot trout
had become mature females, and none had yet changed sex to become male.”
The size regulations will allow more blue-spot trout a chance to spawn
before they reach legal size, and the new maximum size will also protect
some male fish. This will mean a sustainable catch of blue-spot trout
in the future.
“The blue-spot trout is a bit of a chameleon, because it can appear
in two entirely different colour forms,” said Mr Carlos. “As
well as the fish that is dark brown or red in colour with distinctive
blue spots, it comes in ‘Chinese footballer’ colours, which
is a white and yellow fish with large black stripes. Some blue-spot trout
have even been observed changing between these forms. Although some anglers
have mistaken the Chinese footballer for a different species, they are
both blue-spot trout.”
“The blue-spot trout can also be mistaken for the common coral trout.
The most reliable way to tell them apart is by their pectoral fins, which
are on the side of their body. The blue-spot always has dark, non-transparent
pectoral fins, while all other species of coral trout have transparent
ones,” Mr Carlos said.
The CRC Reef Coral Trout 2-sided A4 poster shows the different types of
coral trout in Queensland and explains how to tell them apart. Anglers
are encouraged to download
a copy from the CRC Reef website.
For more information:
Mr Gary Carlos, CRC Reef and James Cook University, 07 4781 6081, gary.carlos@jcu.edu.au
Ms Chloe Lucas, CRC Reef Media Liaison, 07 4729 8450 or 0408 884 521,
chloe.lucas@crcreef.com
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