Conserving Threatened Australian Fishes: Nannopperca oxleyana and Maccullochella ikei
The protection and conservation of animals and plants threatened with extinction is an important issue in today's society. Within Australia, both the Commonwealth and State governments have responsibility for preparing recovery plans that aim to prevent a threatened species from becoming extinct. Among other things, the recovery planning process involves using knowledge of the basic biology of the species to assist in mitigating impacts of humans. Unfortunately, this necessary information is lacking for many of Australia's threatened fish species. For this reason, two collaborative PhD research projects involving NSW Fisheries and Southern Cross University are investigating the biology of two of Australia's most endangered fish species, the Oxleyan pygmy perch Nannoperca oxleyana and the eastern freshwater cod Maccullochella ikei.
The main focus of the Oxleyan pygmy perch research is to understand how the perch disperses, what factors make a particular environment suitable or unsuitable for its survival, and whether human activities have disrupted these processes. Some of the biological characteristics of this species such as its age and growth rate, early development and reproduction will also be examined. When synthesised, this information will help shed light on why the perch occurs where it does and why its numbers appear to vary considerably within and among water bodies. The documentation of the early life of the Oxleyan pygmy perch has begun at the Port Stephens Fisheries Centre with fish mating and spawning over the last summer season. An example of the early development stages of the perch can be seen in the photos below.
The eastern cod research project aims to determine the age, growth and diet of the cod and the early development and swimming abilities of their larvae. Spawning behaviour, movement patterns and habitat preferences of cod larvae and adults are also being studied.
Research into the breeding habits of eastern cod in the wild began in late 2003. Nine eastern cod spawning sites were located and monitored in a 50-kilometre stretch of the Mann-Nymboida River, in north-eastern NSW. The preliminary observations suggest that the breeding season for eastern cod spans a two month period, from late August to late October. Eastern cod appeared to provide a high level of parental care to the eggs for up to nine days after spawning. It is also possible that different mating pairs used the same spawning sites. These findings may greatly assist in the effective management of eastern cod and their habitat.
Eggs of Oxleyan pygmy perch and a 7 day old larva ( ã Jamie Knight).