Department of Environment and Conservation

Walpole

When William Nairne Clark and his party rowed into Nornalup Inlet—and thence up the Deep and Frankland rivers—in 1841, he recorded ‘lofty wooded hills, with tall eucalypt trees growing close to the water’s edge, and crowning the summits of these high hills, thus casting a deep gloom over the water and making the scenery the most romantic I ever witnessed in other quarters of the globe’.

 

The Walpole and Nornalup inlets lie about 450 kilometres south of Perth on WA’s south coast. The town is adjacent to the shallow (at most one-metre-deep) 100-hectare Walpole Inlet, which is fed by the freshwater Walpole River. The larger (1300-hectare) and deeper (up to five metres) Nornalup Inlet is fed by the freshwater Deep River and the saltier Frankland River. The Deep and Walpole rivers have forested catchments, while 54 per cent of the Frankland headwaters have been cleared for farms, making the run-off water somewhat saline. It has been proposed that the Walpole and Nornalup inlets and the tidal parts of the Frankland, Deep and Walpole rivers be made a marine park.

 

The estuaries are joined by a natural one-kilometre-long and two-metre-deep channel, bordered by steep granite hills and rocky shores. These are known locally as ‘The Knolls’ and are covered with dense karri forest. Other channels have been dredged to allow boats to navigate from the town jetty to the ocean bar. Because the inlet mouth is protected from prevailing winds and swell by an adjacent rocky headland, and due to the high rate of water discharge into the system from the three rivers, the estuaries form the only permanently open estuarine system in the south-west. As a result, the Walpole and Nornalup inlets experience marine-like conditions for most of the year, and are more biologically diverse than most estuarine systems in south-western Australia.

Biological diversity

Surrounded by undulating hills and majestic forests, the tranquil waters of the Walpole and Nornalup inlets support seagrasses, algae, a diverse array of shellfish and other animals living in the estuary floor, both marine and estuarine fish species and a variety of waterbirds, seabirds and shorebirds. Polychaetes, crustaceans and molluscs dominate this fauna. Polychaete worms are abundant throughout the estuary and a number of small aquatic snail species can be found in the fringing rushes. Typical estuarine bivalves such as mussels and trough shells are found near the entrance to the Frankland River. Some prawn species, the blue swimmer crab and mud burrowing crab are also found in the inlets.

The open inlet mouth, the mixing of fresh and salt river waters, river deltas and two large inlets result in diverse marine habitats and a great range of fish species. Black bream, whiting, trevally, herring, juvenile Western Australian salmon and even pink snapper are just a few of at least 40 fish species that have been recorded here, including larger fish such as sharks, which are uncommon in other estuaries. The smooth hammerhead shark, southern shovelnose ray, black stingray, eagle ray and gummy shark have all been found from the Walpole and Nornalup inlets, with eagle rays and gummy sharks being particularly abundant, though gummy sharks are confined to the outer basin of the Nornalup Inlet where salinity is the highest.

Black swans, ducks, grebes, swamphens, moorhens, coots, cormorants, herons, egrets, ibis, pelican, whimbrel, sandpipers, stints, oystercatchers and plovers—among other birds—all use the proposed marine park. Gulls and terns are abundant in the area, and shearwaters, gannets and albatross may also be observed. Ospreys and white-bellied sea eagles ply the inlet waters for fish. These large predatory birds are major attractions for nature-based tourism in the inlet system. Migratory shorebirds utilise the tidal delta flats.

Recreation and management

The untouched nature, wildlife and scenic quality of the inlets provide a wealth of opportunities for nature-based tourism, canoeing, boating, water sports, nature appreciation and recreational fishing. A major attraction of the inlet system to visitors is the perception of ‘wilderness’ that can be experienced, particularly in parts of the Nornalup Inlet and the Frankland and Deep rivers.

Management of the proposed marine park will focus on research, monitoring, education and interpretation, and public participation programs. Such programs will allow managers and scientists to gain a better understanding of the estuarine ecosystem, and to assess and manage the impacts of human activities in the area.

The plan, when implemented, will conserve the Walpole and Nornalup inlets system to the approximate limits of tidal influence in the Frankland, Deep and Walpole rivers. The environmental condition of estuaries is closely linked to the condition of surrounding catchments and tributary waterways. The proximity of the adjacent Walpole-Nornalup National Park provides an exceptional opportunity to manage the interconnected terrestrial and aquatic ecosystems as a single unit, so the indicative management plan is integrated with the management plan for the Walpole Wilderness Area and Adjacent Parks and Reserves.

The proposed marine park will protect the plants and animals and the wilderness character of the area, while allowing visitors to continue to fish, tour and holiday on and around the inlets.

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