Wild Science - 23 August 2007

Martin De Graaf

Research Scientist - Freshwater Fisheries; Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries.

FRESHWATER FISHERIES AND BIODIVERSITY IN THE SOUTH-WEST OF WA

Most of the freshwater fish and all of the freshwater crayfish species in the south-west of Australia are endemic to the region and occur nowhere else in Australia. The iconic marron is the third largest freshwater crayfish in the world and supports an important, strictly recreational fishery. Over the years, however, marron stocks have been gradually declining. Several native fish species are threatened with extinction due to the spread of feral fish species and degradation of their habitat. The Department of Fisheries in cooperation with universities and other government agencies is conducting research and implementing programs to protect the aquatic fauna for future generations.

Brian Jones Bsc(Hons) Ph.D. MRSNZ

Principal Fish Pathologist, Supervising Scientist - Aquaculture & Biosecurity; Department of Fisheries.

SCIENCE SUSTAINABILITY AND SOUTHERN WATERS: THE ROLE OF FISH HEALTH

Disease affects all aquatic animals and is a function of the relationship between an animal, its environment and the disease agent. Parasites and diseases are common and new and emerging diseases occur regularly. Perhaps the best example of this was the pilchard mortalities along WA's southern coastline in 1995 and 1998. The Department of Fisheries maintains a fish health unit within the Research Division, which is responsible for diagnosing, monitoring and managing aquatic animal diseases in Western Australia, using modern science methodology. This presentation shows some of the successes and future sustainability challenges facing both the unit and users of the southern coastline.

Geordie Clapin

DO SANCTUARY ZONES WORK?
EXAMPLES FROM RECENT WORK AT ROTTNEST ISLAND

There are many common misconceptions about the role and effectiveness of marine sanctuary or "no take" zones and public support is often strongly divided either for or against closing off new areas to fishing.

Although there have been many good examples from other locations showing that marine sanctuaries do work, there have to date been very few studies of their effectiveness in the south-west of Western Australia.

This presentation looks at some of the problems associated with establishing effective marine sanctuaries and at monitoring how they are performing. Recent research from Rottnest Island is used as a local example of how effective a reserve can be in preserving fish and crayfish.

Dr Jim Penn

Director Emeritus; Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries.

NATURAL VARIATIONS IN WESTERN AUSTRALIA'S MARINE ENVIRONMENT AND FISH STOCKS, AND HOW SCIENCE CONTRIBUTES TO FISHERIES SUSTAINABILITY.

The waters off the Western Australian coastline are dominated by the unique southward flowing Leeuwin Current, which brings warm tropical water to the lower west and south coasts of the State each winter. This tropical current has created our exceptionally clear coastal waters and extensive seagrass beds, and is responsible for many tropical species extending their geographic ranges down along the lower west and south coasts.

While the Leeuwin current has created a unique and diverse west coast marine ecosystem, it is also the reason for the very low productivity of the State's marine finfish stocks compared with those from other equivalent locations around the world. The comparable west coast regions off South America and South Africa have many similar fish species, but sustain pelagic finfish fisheries, which provide respectively, 300 times and 30 times greater catches, than those in Western Australia. However, in contrast to the low finfish catch situation, the stock of rock lobster occurring along our west coast supports the world's largest rock lobster fishery. The reasons for this great disparity between the current systems and fisheries across the southern hemisphere will be demonstrated during the seminar.

The Leeuwin current and variations in it's year-to-year strength, has also been shown to be a major influence on the annual recruitment and movements of a many of the State's important shellfish and finfish stocks. The effect that these variations in current strength have had on the abundance of these stocks over long periods, and its potential for forecasting the catches which will be available to the rock lobster and some other fisheries, will be demonstrated.

Research to understand these natural cycles in the abundance of our fish stocks and to distinguish them from the impacts of fishing, is a key function of many of the scientific teams at the Western Australian Fisheries and Marine Research Laboratories. The essential role that fishers play in supporting this research and how their data are used in fisheries models to assess the sustainable catch levels for our major fisheries will be illustrated during the presentation.