December 2004
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SPOTTING THE DIFFERENCE BETWEEN CORAL TROUT
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 2003, changes to the Coral Reef Finfish 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. “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 lifespan 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 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. However, effectiveness of the new regulations relies on fishers being able to distinguish the blue-spot from other coral trout species. The blue-spot trout can appear in two entirely different colour forms. As well as the fish that is dark brown or red in colour with distinctive 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. The blue-spot trout can also be mistaken for common coral trout. The most reliable way 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. The CRC Reef Coral Trout double-sided A4 poster illustrates the different types of coral trout in Queensland and explains how to tell them apart.
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