Reproductive biology of the red throat emperor Lethrinus miniatus (Pisces : Lethrinidae) from the southern Great Barrier Reef, Australia

The reproductive biology of the red throat emperor, Lethrinus miniatus (Schneider, 1801) was examined in the southern Great Barrier Reef (GBR), Australia. The species was found to display the characteristics of an incomplete metagynous hermaphrodite based on histological evidence and size frequency information. Over 95% of functional males possessed a remnant lumen, but there was no evidence of oocytes in the testes of males. A single transitional fish was sampled which had both ovarian and testicular tissue present in its gonad. Size frequency data showed that females dominated the smaller size classes with the majority of fish < 40 cm being females. Lethrinus miniatus had an extended spawning season from July-November, although spawning was more pronounced during the spring. Spawning was initiated earlier at lower latitudes. There was no particular size or age when sex change occurred since females older than 20 and males as young as 2-yrs old were sampled.

Should the 40-year-old practice of releasing virulent myxoma virus to control rabbits (Oryctolagus cuniculus) be continued?

Release of virulent myxoma virus has been a key component of rabbit-control operations in Queensland, Australia, since the 1960s but its use rests on anecdotal reports. During a routine operation to release virulent myxoma virus we found no evidence to support the continued regular use of the technique in south-west Queensland. Radio-tagged rabbits inoculated with virulent myxoma virus contracted the disease but failed to pass enough virus to other rabbits to spread the disease. Rabbits with clinical signs of myxomatosis that were shot were infected with field strain derived from the original laboratory strain released in 1950 rather than the virulent strain that has been released annually. There was no change in rabbit survival or abundance caused by the release. Nevertheless, the release of virulent virus may be useful against isolated pockets of rabbits mainly because field strains are less likely to be present. Such pockets are more common now that rabbit haemorrhagic disease virus is established in Queensland.