Neptune Islands

Neptune Islands

Geography
Location	Great Australian Bight
Country
Australia

The Neptune Islands consist of two groups of islands located close to the entrance to Spencer Gulf in South Australia. They are well known as a venue for great white shark tourism.

Description

The Neptune Islands consists of two groups of islands, the North Neptune Islands and the South Neptune Islands. These both sit on the southern aspect of the Australasian continental shelf separated by a distance of 9 km. The North Neptune Islands which are 27.8 km south south-east from the mainland at Cape Catastrophe, consist of a large island of 49 m height and a small islet of 29 m height located 300 m from the main island's north-east point with a combined area of 2.43 km². The South Neptune Islands which are 38.9 km south-south-east from the mainland at Cape Catastrophe are more evenly portioned in height with the northern island being 35 m high and the southern island (also known as Lighthouse Island) rising to 37 m. The Southern group has an area of 2.02 km². A third feature associated with the overall island group is an outcrop of rocks located about 6.5 km north-north-east of the northern group of islands.^[2]

Formation, geology and oceanography

The Neptune Islands were formed between 10800 and 12000 years ago when sea levels rose at the start of the Holocene.^[3]

The islands are remnant igneous inselbergs which have survived the erosive process associated with sea level rise. The remnant rock is described as being ‘a porphyritic granite gneiss and pink granite intruded with dolerite dykes‘. Remnants of the once-overlying calcarenite layers are also present on the upper platforms of the island. The soil is mainly derived from the weathering of the granite with a minor contribution from the weathering of calcarenite strata.^[2]

The seabed falls steeply away from the coast of both island groups. Water depths of 80 m are reached within a distance of 1.5 km from the Northern group and within 1.5 to 2 km from the Southern group.^[4]

Flora and fauna

Plants

While the low profile of the islands do limit what can grow due to wind exposure and salt spray, surveys have shown that the Northern island group (excluding the ‘small satellite islet’) has 35 plant species while the Southern group has 28 species on its north island while Lighthouse Island has 13 species. The latter is attributed to combination of the disturbance caused by activity associated with the formerly-manned lighthouse, airstrip, an introduced goat population that was eradicated in 1968 and burrows made by the large numbers of Short-tailed Shearwaters. Plant species include Sea Celery, Leek Lily, Flax Lily, Coast Tussock Grass, Salt Couch, billy button daisies, Variable Groundsel and an introduced Northern Hemisphere grass, Rat's-tail Fescue.^[2]

Terrestrial animals

The only mammals present are bush rats which are found on North Neptune Island. Birds of prey include White-bellied Sea-eagles, Peregrine Falcon and Swamp Harrier with Australian Kestrels mainly concentrated on the northern island in the South group. Breeding colonies of Cape Barren Geese are present on the Northern group while Short-tailed Shearwaters, Silver Gull and Greater Crested Tern are present on the South group island. Other landbirds include White-fronted Chats, Masked Plovers, Rock Parrots, Welcome Swallows, Silvereyes and Stubble Quails. Sparrows, an introduced species, has established on itself on Lighthouse island. Reptiles identified during surveys include Marbled Geckos on both island groups while the following are limited to the main island in the Northern group - Four-toed Earless Skink, Bull Skinks and Western Brown snakes. The latter are believed to predate on bush rat and bull shinks. ^[2]

Marine animals

New Zealand fur-seals and Australian sea lions are common on all islands, using the island group for breeding. In turn, the presence of these two colonies of sea mammals supports a migratory population of both Great White sharks & Bronze Whalers.^{[citation needed]}

History

The islands were first sighted by Europeans on Sunday 21 February 1802 from HMS Investigator whilst under the command of Matthew Flinders The islands were named ‘Neptune's Isles’, 'for they seemed to be inaccessible to men.'^[5] The islands were subsequently visited by John Lort Stokes in 1840 and later in 1873-74 by Captain F. Howard, RN as part of an ongoing South Australian Government program to map the colony’s waters, identify shipping hazards and assess the suitability of the coastline for settlement.^[6]

During World War II, the Neptune Islands became a strategic military site due to its lighthouse’s location at the approaches to both Spencer Gulf and Investigator Strait. This is evident in the act of the placement of a mine field approximately 25 miles west-south west of the Neptune Islands by the German auxiliary cruiser Pinguin during November 1940.^[7] A naval depot including huts and observation towers was established on South Neptune Island along with a gun which was regularly fired.^[6][8]

Lighthouse

The need for a lighthouse in the Neptune Islands was considered for many years during the 19th century due to the Islands’ relatively low elevation.^[9] In 1901, the light tower from the Port Adelaide Entrance light was relocated to South Neptune Island. This was eventually replaced by a new structure in 1985 and was transported to Port Adelaide on MV Cape Don to become part of the collection of South Australian Maritime Museum which opened in 1986. The new lighthouse was converted to automatic operation in 1990 resulting in the departure of the lighthouse keepers and their families.^[10][11]

Economic activity

Gauno

The Neptune Islands were one of the island sites from which guano was mined under licence from the South Australian Government prior to 1919.^[12]

Fishing

The waters around the Neptune Islands outside of the protected area (see below) are commercially fished for abalone, marine scalefish, rock lobster and sardine. By-catch includes commercially attractive species such as giant crab and octopus.^[13][14]

Tourism and other spin-offs

The Neptune Islands, particularly the North Neptune Islands, have been one of the sites used for shark cage diving to view Great White Sharks in South Australia since the late 1970s. Since 2002, it is the only site within Australia where this activity is legally permitted.^[15][16] The availability of cage diving has attracted professional photographers and others whose efforts are considered by individuals such as Rodney Fox as having 'significantly contributed to worldwide knowledge of shark physiology and behaviour, because film, video, television and print media associated with shark viewing and research activities at the Neptune Islands, have reached a very large global audience'.^[13] Most notable is the underwater sequences of live sharks in the film Jaws that were filmed at the Neptune Islands by Ron and Valerie Taylor in 1974.^[17] Other tourist activities include charter fishing, marine mammal watching and cruise ships visits.^[14]

Protected areas

Neptune Islands Conservation Park

The Neptune Islands Conservation Park includes all the islands in the Group to low water mark with the exception of Lighthouse Island in the South Neptune Islands. The park was proclaimed in 1967 mainly to conserve the New Zealand Fur Seal breeding colony on the southern island of the North Neptune Islands which is one of the largest in Australia. Other features that contributed to the declaration include the small breeding population of Australian Sea Lions on the North Neptune Islands, Australian Sea Lion haul out areas and the heritage listed buildings located on the South Neptune Islands, and the breeding/nesting populations of Cape Barren Goose, White-bellied Sea Eagle, Osprey and Peregrine Falcon. A two nautical mile marine extension was declared under the National Parks and Wildlife Act 1972 (SA), to regulate and manage shark berleying activities around both groups of islands.^[13]

Neptune Islands Group (Ron and Valerie Taylor) Marine Park

The Neptune Islands Group (Ron and Valerie Taylor) Marine Park consists of two separate areas - the waters within two nautical miles of the coastline of both the North Neptune Islands and the South Neptune Islands at median high water.^[18] The marine park came into existence on 29 November 2012 as part of a state wide network of marine protected areas. When announcing the launch of the marine park network, Jay Weatherill, the South Australian Premier, announced the renaming of the Neptune Islands Group Marine Park to the Neptune Islands Group (Ron and Valerie Taylor) Marine Park in recognition of the Taylors' contribution to 'the conservation of sharks, sea lions and other marine species.'^[19][20]

Administration

Administratively, the Neptune Islands Group (Ron and Valerie Taylor) Marine Park entity 'overlays' the entirety of the Neptune Islands Conservation Park. Activities within the dual entity is restricted to 'scientific research, tourism operations, competitions and organised events, commercial film-making (including sound recording and photography), installation of vessel moorings' and any activity that can be argued on a merit basis. Access to both terrestrial and marine areas is controlled by a permit system administered by one government agency.^[21]

Cultural heritage

Aboriginal heritage

Little is known about Aboriginal heritage associated with the Neptune Islands. While it is likely that the islands can be seen from the Eyre Peninsula coastline and that the Islands may have more accessible to aboriginal people during the recent ice age than during the present day, Native Title claims lodged in 1996 and 1997 respectively for southern Eyre Peninsula by the Barngarla and the Nauo peoples did not include the Islands.^[13][22]

Lighthouse facility

The keepers' cottages, store, outbuildings, stone fences, stone rainwater tanks, grave sites & footings of the now-removed first lighthouse collectively known as the South Neptune Island Lighthouse Complex are protected under the Heritage Places Act 1993 (SA) and the Development Act 1993 (SA).^[23]

Shipwrecks

S.S. Yandra, circa 1930

• Frances, Cutter, wrecked at South Neptune Island on 29 August 1840.^[24]
• ''Venus - Cutter, wrecked at North Neptune Island on 14 June 1946.^[25]
• Yandra - Motor vessel, ran aground in dense fog onto South Neptune Island on 25 January 1959.^[26]
• Saint Michele - Fishing boat, wrecked at South Neptune Island on 30 March 1965.^[27]
• Gloridia V - Cray-fishing boat, wrecked at North Neptune Island on 12 March 1977.^[28]

As of October 2013, the only major shipping casualty has been Yandra which, ironically, was serving as the lighthouse’s supply ship at the time of her loss.^[29]

See also

• Protected areas of South Australia
• Hertford (1920)

References

External links

• Wikivoyage: Diving in South Australia/Shark cage diving at the Neptune Islands

North Neptune Island 35°23′00″S 136°06′00″E / 35.38333°S 136.10000°E / -35.38333; 136.10000 (North Neptune Island) South Neptune Island 35°33′00″S 136°12′00″E / 35.55000°S 136.20000°E / -35.55000; 136.20000 (South Neptune Island)