The Bioregional Seascape
The Natural Capital of Open Coasts
Management Themes
Management Responses

The Bioregional Seascape
Open coastal waters under Victorian jurisdiction extend 5.5 kilometres from the shore and cover almost 7000 square kilometres. They range from waters of the Southern Ocean in the west, through Bass Strait, to the edge of the Tasman Sea in the far east. Four IMCRA regions have been identified along the open coast: Otway, Central Victoria, Flinders and Twofold Shelf. The habitats in these waters range from the intertidal beaches and rock platforms to those of the sea floor, which off East Gippsland is almost 120 metres deep. It also includes the pelagic habitat formed by the water column. There are numerous offshore islands from Lawrence Rocks in the west to Gabo Island in the east. Sediments in offshore waters change from carbonate sands in the west, through the muds of central Bass Strait to quartz sands in the east. Subtidal rocky areas are scattered throughout but predominate off much of the western coast and south of Wilsons Promontory. Low limestone reefs representing old shorelines occur offshore in various places. Western Victoria is mainly influenced by cool sub-Antarctic water while the east is influenced by the warm Eastern Australian Current that originates in the tropical north. The sea surface temperature is approximately three degrees higher in eastern Victoria than in the west.

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The Natural Capital of Open Coasts
The Victorian open coast supports a diverse temperate fauna and flora that is largely endemic to southern Australia. Rock platforms and shallow subtidal reefs are dominated by kelps and other algae. Deeper reefs are covered in a diverse range of sessile invertebrates such as sponges, bryozoans, and gorgonians. Amphibolis seagrass beds are common in sand adjacent to shallow rocky reefs. A rich fauna also occurs in unvegetated subtidal sand and mud habitats. The diversity of marine invertebrates in the subtidal sands off East Gippsland is significantly higher than that found in similar habitats elsewhere in the world. Many cool temperate species have their eastern distribution limit within central Victoria, particularly between Bunurong and Wilsons Promontory. A number of New South Wales species persist into eastern Victoria including the Sydney Rock Oyster and the Black Sea Urchin.

The living resources of the Victorian open waters have never been quantified but probably include over 500 species of fish and almost 1000 species of algae. Seals, penguins and Short-tailed Shearwaters breed on offshore islands. Offshore islands and the near-shore waters are also used by a large number of migrant, non-breeding species of birds and mammals. For some species, these islands support the only breeding and roosting colonies in Victoria and therefore are recognised as significant at the national level.

Several whale species visit our shores, and three of these are threatened with extinction. Most endangered of these is the Southern Right Whale, which calves off Warrnambool. As a result of whaling activity, the population of this species fell from tens of thousands to only about 1000, and is now recovering very slowly. This species has been listed under the Flora and Fauna Guarantee Act 1988 and an Action Statement is being prepared. Management of the calving and nursery grounds and migration routes used by Southern Right Whales focuses on maximising the reproductive potential of the species.

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Management Themes
The living resources of our open coast were first utilised by indigenous peoples who collected the abundant shellfish and ate the occasional seal or beached whale. Sealing and whaling were the first two industries established by Europeans within Victoria. These animals were rapidly over-exploited. Commercial fishing was at first limited to inshore areas where barracouta and lobster were taken by boats under sail. Other fisheries gradually became established with improved technology and new discoveries: a shark fishery in the late 1930s, a mixed trawl fishery out of Lakes Entrance in the late 1940s; abalone in the early 1960s and an eastern Bass Strait scallop fishery in the early 1970s. Recent fisheries include wrasse, king crabs, and aquarium fish. Offshore recreational fishing has also expanded with improved technology. Line fishers target various species including snapper and sharks. Divers take abalone, lobster and various reef fish. Intertidal shellfish and bait collecting is also an important recreational pursuit. Aquaculture in Victorian offshore waters is currently limited to abalone ranching.

Although commercial fishing is recognised as a beneficial use of resources, it is recognised that there are some impacts that vary with each fishery. Sea floor habitats can be damaged by scallop dredging and bottom trawling with Danish seines and otter trawls. Long-lived habitat-forming animals such as sponges and bryozoans are particularly vulnerable. Trawl fisheries catch a diverse mix of species including long-lived fish with low levels of fertility which are more vulnerable to over-exploitation. Some sharks, lobster, reef fish and intertidal shellfish are either over-exploited or vulnerable to over-exploitation by commercial or recreational fishers. Other uses along the open coast include recreational diving, surfing, boating and other water sports, ecotourism, shipping, oil and gas exploration and production, waste disposal from outfalls, sea floor cables and pipelines. Current oil and gas production is outside Victorian waters, however the as yet undeveloped Otway basin includes nearshore areas. Potential environmental impacts arise through discharges such as drilling muds and cuttings, formation waters, outfalls and from removal of installations at the end of their effective life. There are seventeen waste outfalls along the Victorian open coast. Sewage treatment varies, not all sewerage treating is to a secondary level.

The seabed is almost totally under public ownership. Potential long-term lessors include the aquaculture and petroleum industry. There are two major oil and gas basins off Victoria’s coast, and exploration continues in these areas.

Marine reserves include areas off Point Nepean, Bunurong and Wilsons Promontory. Current reserves are not comprehensive, adequate or representative of the Victorian open coast. Only the sanctuary zone within the Bunurong Marine and Coastal Park is totally protected from extractive use.

Natural habitat cover has been modified in several areas. Constant bottom trawling and scallop dredging in eastern Bass Strait may have removed the larger epibenthos species such as sponges, bryozoans and corals. The effect and scale of this habitat loss is unknown. There is anecdotal evidence that the Giant Southern Kelps have declined in south-eastern Australia over the past 25 years, which is possibly related to above average sea-water temperatures. Few introduced species currently occur along the open coast; none are considered pest species.

The islands, many of which are wildlife reserves, are managed primarily to protect the biodiversity assets, some of which are of national significance, for example those on Lady Julia Percy Island. Some species may breed in tens of thousands while others have much lower numbers. Rabbits and cats have been an historical problem on some islands. Maintaining fox free status and ensuring human disturbance is controlled, both on the islands and adjacent waters, is critical for the maintenance of these breeding colonies and other biological assets.

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Management Responses
Victoria’s open coast bioregions are, like the bay and inlet environments described in the previous section, largely intact and under public ownership. Like those partially enclosed waters, open coasts are affected by catchment management practices on adjacent lands, as well as by the marine industries, shipping and recreational activities. Hence the key management approaches for open coast bioregions echo those established for bays and inlets.

The priority management responses for land and water managers and planners are the following:

• Ensure the ecologically sustainable harvest of fisheries.
• Encourage and assist the fishing industry to adopt technologies and develop codes of practice to minimise damage to sea floor habitats and impact on non-target species.
• Increase understanding, protection and monitoring of vulnerable habitats, particularly kelp and epibenthic communities affected by trawling or dredging.
• Establish a comprehensive, adequate and representative system of marine reserves.
• Increase the understanding and protection of vulnerable and threatened species and their habitats, particularly those that communally breed or roost on islands.
• Encourage the non-extractive use of our living marine resources.
• Plan for oil spill contingencies from shipping or fixed installations in open waters.
• Encourage sustainable and environmentally sensitive aquaculture.
• Minimise the environmental impacts of exploration and extraction of earth resources, particularly oil and gas.
• Improve understanding of offshore areas through mapping marine habitats and developing an inventory of the biological resources.