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Southern Port Phillip Bay including Port Phillip Heads

Southern Port Phillip Bay including Port Phillip Heads is one of the most treasured marine environments in Victoria. Within this region are six fully-protected marine areas that make up the Port Phillip Heads Marine National Park.

A dramatic underwater canyon, tall kelp forests, colourful sponge 'gardens', seagrass meadows, expansive sandy plains, surging currents and tranquil bays and backwaters - this area has them all. The diversity and abundance of marine plants and animals is immense.

What are the key natural features of this area?

  • The underwater canyon at the entrance to the Bay (known as the ‘The Rip'). This deep U-shaped feature is approximately 300m wide and up to 90m deep. The steep-sided drop-offs, gullies, rubble slopes, pinnacles, ridges, overhangs and associated fast-flowing tidal currents make it a unique marine area in Victoria and southern Australia.
  • Strong tidal currents. Depending on the tides, currents into and out of the Bay can ‘run' at up to 3 metres per second under normal conditions but exceed 4.5m per second in extreme conditions.
  • The prolific and highly diverse sponge ‘gardens' on the vertical reef faces, crevices, and deep caverns at Port Phillip Heads are nourished by the abundance of floating food swept with the currents. The sponge ‘garden' communities include an array of soft corals, hydroids, jewel anemones and sea tulips that are visually spectacular on a national scale.
  • The intertidal rock platforms at Point Lonsdale and Point Nepean are home to the highest diversity of marine invertebrates of any sandstone reef in Victoria.
  • A high diversity of seaweed species. Over 118 species have been recorded at Port Phillip Heads, comprising 53 species of red seaweed species, 48 brown seaweed species and 16 green seaweed species.
  • Small forests of the giant kelp Macrocystis angustifolia, although these forests have declined significantly in the area over the past 30 years. These forests have been known to grow to over 10m in height in the area.
  • The high diversity of resident fish species at Port Phillip Heads, including more than 43 species. It is possible to see up to 23 species in one dive. The main species include wrasse (Notolabrus tetricus, N. fucicola and Pictilabrus laticlavius), Herring Cale Odax cyanomelas, sea sweep Scorpis aequipinnis, the Magpie Perch Cheilodactylus nigripes, the Six-spined Leatherjacket Meuschenia freycineti, and the Scaly Fin Parma victoriae.
  • The populations of the Western Blue Devilfish Paraplesiops meleagris on the deep reefs of the area. Port Phillip Heads is considered an important stronghold for Victoria's population of this territorial and beautiful fish.
  • Popes Eye, a small horseshoe-shaped ring of bluestone blocks constructed between Queenscliff and Sorrento is the only site in Victoria where fishing has been prohibited for an extended period (since 1979). Fish are very abundant and include wrasse, morwongs, old wives, scaly fin and perch.
  • A population of about 80 Bottlenose Dolphins Tursiops truncatus primarily resides in Ticonderoga Bay near Portsea and the area is a recognised refuge for the species. The dolphin population relies on feeding opportunities presented by migratory species such as squid, mullet and barracouta that move through the Bay's entrance.
  • The area is renowned for its diversity of migratory wader birds. Swan Bay is an internationally significant shorebird habitat for resident and migratory species. Combined with Mud Islands, it is the second most significant site for shorebirds in Victoria (after Corner Inlet) and a key wintering site for the critically endangered Orange-bellied Parrot Neophema chrysogaster.
  • Swan Bay's significant seagrass meadows that are dominated by sparse beds of Zostera/Heterozostera seagrass. These areas are an important nursery area for King George Whiting Sillaginodes punctata. Spotted pipefish Stigmatopora argus are also common.
  • The Portsea Hole about 500m from the Portsea Pier that is a remnant of the old Yarra River valley. The top of the hole is at about 14m in depth, but drops rapidly to approximately 33m in depth. Popular with divers, it has abundant fish, encrusting algae, sponges and soft corals.
  • Extensive shallow reefs at Point Nepean support a variety of marine life including Victoria's marine state emblem the Weedy Seadragon Phyllopteryx taeniolatus, cuttlefish and numerous seaweed and invertebrate species. Significant seagrass meadows of Amphibolis antarctica also exist in the area.
  • The fine sands and muddy sediments around Mud Islands are an important habitat for many invertebrate species, including small crustaceans and segmented worms that, in turn, are food for many birds, including endangered and migratory species.
  • The dense seagrass beds both within and around Mud Islands provide important feeding and nursery areas for fish species such as King George whiting Sillaginodes punctata. Several species of sharks including the Bronze Whaler Carcharhinus brachyurus are known to commonly bask in the shallow waters surrounding Mud Islands.
  • The seagrass meadows of Swan Bay are an important feeding and nursery area for numerous fish species including leather jackets, flounder, King George Whiting, Black Bream, garfish and flathead. Forty-four fish species have been recorded in Swan Bay. Black swans also feast on the seagrass meadows.

Marine Protected Areas

Port Phillip Heads Marine National Park
Barwon Bluff Marine Sanctuary
Ticonderoga Bay Sanctuary Zone