Marine Systems

The waters off the Western Australian coast, are influenced by the Leeuwin Current. The current transports warm and low saline waters from the tropical north to southern Western Australia. The Leeuwin Current is of extreme importance to the marine environment, of particular importance to the NAR is its influence on the recruitment of the Western Rock Lobster (Panulirus cygnus) and the survival of corals in the Houtman Abrolhos Islands.

The coastal waters of the NAR is open and exposed, with substantial current and wind-driven water movements. The population is also small, with only about 60,000 people living in the NAR, half of whom are resident in the Geraldton area. There is little heavy industry along the coastline. These features combine to ensure that, while relatively few measurements have been made, overall water quality is thought to be non-impacted (NACC, 2005).

The coast of the NAR contains many offshore islands. The islands are grouped into 12 nature reserves managed by the Department of Parks and Wildlife to conserve their ecological, recreational, commercial, educational and cultural, and research values. The islands are host to a number of endangered fauna and are important examples of island habitats within the Central West Coast marine bio-region (NACC, 2005). The Houtman Abrolhos islands in particular, has a unique mixture of tropical, temperate and Western Australian endemic marine species.

Jurien Bay Marine Park and a few nearby islands form the only major breeding area for Australian sea lions along the western coast of Australia. The park also has the highest diversity of seaweed species in Australia and its extensive seagrass meadows provide shelter and nursery habitat for many fish and other marine creatures such as western rock lobster (DPaW, 2014b).

The west coast of Western Australia, between Ningaloo and Rottnest Island, is a key center of biodiversity. Eighteen hotspots of coral reef biodiversity have been found. The Abrolhos are one of four reef systems that constitute the hotspot. The Abrolhos’ total diversity is second to Ningaloo Reef, but has far more restricted range species (NACC, 2005).

The waters surrounding the Abrolhos islands have an incredible abundance of coral, macroalgae, invertebrates and fish which provide a spectacular setting for diving and snorkelling. These waters have been given special status as a Fish Habitat Protection Area for the conservation of fish and fish breeding areas and the aquatic ecosystem, and for the management of aquatic tourism and recreational activities. The Abrolhos and Jurien are classified as a Commonwealth Marine Reserve, due to major conservation values (i.e. important foraging areas for sea lions). These Commonwealth Marine Reserves also both comprise National Marine Park zones.

Along the continental coastline, subtidal reefs, limestone drop-offs, macroalgae and seagrass beds in sandy areas also provide outstanding submerged seascapes. Wreck diving is popular, and dive trails are being set up in some areas (Jurien Bay and Abrolhos) to highlight local features.

The species diversity of seagrass, macroalgea, fish, birds, invertebrates and other marine flora and fauna is very high and the combination of both temperate and tropical species notable. Many migratory species, particularly Cetaceans (whales and dolphins) and seabirds utilise the NAR’s marine system. Some of the specially protected species that occur in the region include:

See the conservation significant fauna list, for details of significant marine fauna recorded in the NAR, to help you identify these species check out the Protected Species ID Guide.

The Abrolhos is a major nesting area for seabirds of International significance, but populations are lower than they were before European settlement. At least 15 species of seabirds breed on the islands of the Jurien Bay Marine Park, including the Roseate tern, whose numbers have increased considerably in recent years (Gaughan et. al. 2003). Australian sealions (Neophoca cinerea) are also often-seen, with some of the northernmost and important breeding sites of the Australian sea-lion including North Fisherman, Buller, East Beagle and the Abrolhos Islands. Approximately 800-1000 occur on the west coast (Gales et al. 1994) and this species is protected under the Wildlife Conservation Act 1950.

Commercial and recreational fishing are major activities along the coast of the NAR. The principal commercial fishery in this region is the western rock lobster fishery which is Australia’s most valuable single-species wild capture fishery. There are also significant commercial trawl, dive and pot fisheries for other invertebrates including scallops, abalone, blue swimmer crabs and octopus. Commercial fishers take a range of finfish species including sharks, dhufish, snapper, baldchin groper and emperors using demersal line and net methods (Fletcher and Santoro, 2012).

The Department of Fisheries, established and designated under the Public Sector Management Act 1994, is the department principally assisting the Minister for Fisheries in the administration of legislation under five State Acts of Parliament.

The Abrolhos Islands are protected within a ‘Fish Habitat Protection Area’, and are not considered by the Department of Fisheries to be at unacceptable risk from fisheries related activities. There are a number of research programs including monitoring of the health of coral communities at the Abrolhos Islands (Fletcher and Santoro, 2012).

Recreational fishing is also popular in the NAR, as it is in Western Australia more generally, and is a significant contributor to the regional tourist economy. The NAR is located in the West Coast recreational fishing region,  check out the online Species Identification Guide.

Aboriginal people have a spiritual and physical connection to the marine environment, with the creation of stories of Noongar and Yamaji people containing many references to the sea and its inhabitants. According to the creation mythology of many Yamaji language groups, a battle took place between the Rainbow Snake and a mythological marine creature (some say shark others say serpent).

Some local language groups believe this battle took place near the mouth of the Murchison River and the Abrolhos Islands were created as a result. As the Abrolhos are not visible from the mainland and the local Aboriginal groups are not seafarers, knowledge of the existence of the Abrolhos Islands may come from a time when the sea level was lower. Noongar people maintain their cultural link to the coastline with mythological explanations for the existence of the many coastal islands. Cultural caveats exist on many of these islands, with access to an island and its resources often restricted to particular members of the community (eg Some of these islands are designated womens’ places).

Although there is a long history of use of the coastal areas by Aboriginal people, a better understanding of the significance Aboriginal people place on the marine environment in the Northern Agricultural Region is still required. The existence of fish traps and the number and contents of middens provide evidence that marine molluscs and fish were an important food source.

There are native title claims that cover inshore marine areas of the region, and there may have been use of what are now offshore islands during periods of lower sea-level.

Click features on the map for more information. View full page map.
  • Champion Bay Seagrass

    A number of dominant seagrass species including Amphibolis antarctica, Amphibolis griffithii and Posidonia sinuosa cover the shallow calcarenite reef that runs parallel to the beach for up to 1 km offshore. This seagrass is often deposited on the beach. Previous dredging operations associated with the redevelopment of the Geraldton Port in 2002-03 resulted in increased turbidity and sedimentation in the area and had a significant impact on the seagrasses of Champion Bay. The recovery of these seagrasses was researched by the CSIRO from 2005-07, which concluded that seagrass recover had begun and seagrass health continued to improve. For more information see ‘Applying the learning’ prepared by Mulligan Environmental.

  • Houtman Abrolhos Islands

    An archipelago of 122 islands that lie between 60 and 80 km off the mid-west coast of WA. The Abrolhos Islands stretches for around 100 km and consists of three groups of islands, and accompanying coral reefs – the Wallabi-North Island Group; Easter Group; and Pelsaert (or Southern) Group.

    The Houtman Abrolhos Nature Reserve has been an A-Class Reserve since 1929 for the purposes of: ‘Conservation of flora and fauna, tourism, and for the purposes associated with the fishing and aquaculture industries.’

    Along with being host to a diverse and unique range of both terrestrial and marine plants and animals, the Abrolhos Islands are significant from a historical perspective in relation to numerous shipwrecks as well as the whaling, guano mining, and fishing industries.

    The islands provide the northern-most habitat of the Australian sea lion (Neophoca cinerea), which are classified as Vulnerable.

    Areas of the Abrolhos below the high water mark and including State territorial waters form part of a Fish Habitat Protection Area (FHPA) that was declared in 1999.

    More information can be found in the Department of Fisheries WA, The Abrolhos Islands Information Guide, 2012.

  • Jurien Bay Marine Park

    Jurien Bay Marine Park was declared in 2003 and encompasses the marine waters between Wedge and Green Head. Extending for around 5.5 km offshore, the Park contains an extensive limestone reef system, forming shallow lagoons and seagrass meadows, and also incorporates many island nature reserves that provide habitat for rare and endangered animals, including dibblers (an endangered marsupial) and various seabirds.

    The seagrass meadows that occur within the Park are important nursery habitat for many marine animals, including the western rock lobster. The Park also contains the sole major breeding area on the western coast for the rare Australian sea lion, supporting a population of approximately 800. The unique and biological diversity of the Park is due to a number of species that are at the limit of their geographical distribution – leading to a mix of temperate and tropical species.

    The Marine Park is popular for recreational activities such as scuba diving, snorkelling, swimming, windsurfing and surfing. Fishing is allowed in the Marine Park, with the exception of defined sanctuary and scientific reference zones (bag limits, minimum sizes and licences apply). Spearfishing, crabbing, rock lobster fishing and netting are restricted in some zones. For more information see: The Department of Fisheries WA website and the Jurien Bay Marine Park brochure.

     

  • Kalbarri Blue Holes Fish Habitat Protection Area

    The Blue Holes form part of an inshore coastal limestone reef system west of Kalbarri, and includes permanently submerged  and intertidal sections. The Blue Holes area is a popular recreational area and plays host to an abundance of aquatic animals and fish. The area was declared a Fish Habitat Protection Area (FHPA) in 2007 due to its special ecological and community significance. Due to the fragile and important ecosystem special management requirements are in place to help ensure its long-term sustainability, including:

    • All fishing is prohibited;
    • The use of motorised vessels (including recreational boating and jet skis) are prohibited;
    • Special care should be taken to dispose of rubbish responsibly;
    • Aquatic recreation activities (including snorkelling and scuba diving) are encouraged, when pursued safely and responsibly;
    • Aquatic nature-based tourism is encouraged to help promote awareness of the environmental values of the area, however operations are subject to licencing requirements and guidelines for responsible operations must be adhered to.

    More information can be found in the Department of Fisheries Kalbarri Blue Holes FHPA, 2009.

  • Seagrass Meadows

    Seagrasses are flowering plants that complete their life cycle submerged in seawater. Western Australia has the world’s highest diversity of seagrasses, with 27 species occurring in shallow waters off the coast. Seagrasses form a vital component of marine ecosystems through their services as primary biomass producers, sources of habitat (including breeding and nursery areas) and dissolved oxygen, sediment traps, and nutrient cycling. Seagrass distribution is determined by a combination of shelter, sediment, turbidity, nutrient, temperature, current and tidal influences.

    Extensive seagrass meadows occur in protected near-shore areas of the NAR, where clear water, low nutrients and sandy sea floors prevail, and are dominated by the long strap-like Ribbonweed or Strapweed (Posidonia spp) and the thin-stemmed Wireweed (Amphibolis spp).

    Seagrass habitats are fragile and susceptible to damage and can take many years to recover from disturbance, such as physical damage/removal and shading due to algal blooms (as a result of increased nutrients), and sedimentation (due to dredging activities and erosion in catchment areas).

    More information on seagrasses in Western Australia can be found in the following publications: Flowers of the Ocean: WA’s Expansive Seagrass MeadowsThe Wonders of Weed Information Sheet; Fisheries Fact Sheet: Seagrasses; Establishing Reference and Monitoring Sites to Assess a Key Indicator of Ecosystem Health (Seagrass Health) on the central west Coast of Western Australia (see references).

     

  • Seven Mile Beach Rock Lobster Monitoring Site

    This shallow water site is located near the centre of the western rock lobster’s range of distribution. Studies conducted at the site provide much of the published data on rock lobster foraging and recruitment.

Leave a Reply

Your email address will not be published. Required fields are marked *

19 − 13 =