A look into the history of an island off the Esperance coast

Salisbury Island from above.
Salisbury Island from above.

A research expedition using sophisticated drone and sonar technology is to uncover the secrets of Salisbury Island, one of the most eastern and isolated of the Recherche Archipelago's 105 islands.

Located 160 kilometres east of Esperance and 50 kilometres from the mainland, this five kilometre long island covering about 790 acres had been identified by previous expeditions as a valuable scientific laboratory because of its 14,000 year isolation from the mainland, much longer than any other island off the Western Australian coast.

Formed by a massive limestone scarp sitting on top of a granite dome, the island is dotted with caves both above and below the waterline that hold some of the island's many scientific treasures.  The granite forms a serrated, razor sharp reef around the island forming a continuous surf break, making it almost inaccessible.

Known from previous studies carried out in 1950, 1977 and 1982, is the insular population of Black-Flanked Rock wallabies, a vulnerable species only found on this island south of the Pilbara in Western Australia, and also for the largest known  colony of New Zealand fur seals in the State, with over half of the breeding population located here.

Its fauna includes a genetically unique population of Southern Bush Rats, and an important sea-bird breeding rookery.

Thirty-nine species of plants have been identified in four distinct areas of vegetation types that form a dense, nearly impenetrable 1.5 metre high thicket across the island.

Salisbury has a rich human history, with ancient people occupying the site before the island was cut off from the mainland at the end of the last Ice Age. Stone artefacts identified by traditional owners and archaeologists on the island demonstrate this ancient connection.

Europeans came much later and it is likely that Nuyts (1627) and Vancouver (1791) sailed past the island while D'Entrecasteaux (1791) named the group of islands that includes Salisbury the South East Isles.

Matthew Flinders surveyed the Recherche Archipelago in 1802, and Commander JW Combe is credited in naming the island, probably after the Marquees of Salisbury, a United Kingdom peerage line that included a British prime minister. He was carrying out a hydrographic survey of the region in 1900-01.

Black-flanked Rock Wallaby is a local resident of the island.

Black-flanked Rock Wallaby is a local resident of the island.

Sealers were known visitors between 1825 and 1850 to cull fur seal and Australia sea lions, but they never camped because of the lack of a sheltered anchorage.

Salisbury Island made international news on Sunday October 7, 1894, when 196 passengers from the ill-fated Rodondo that hit the nearby Pollock Reef and sank, were landed on the island. All but four were rescued.

In 1980, two claims were lodged to mine the island's guano, phosphate and limestone deposits. The then Department of Fisheries and Wildlife sent a research party to the Island in March 1982 to determine the impact mining would have on the island's rich and diverse ecology. The mining venture never got started.

The latest expedition is being organised by a local group, Finding Salisbury. It will land a team of archaeologists, biologists and a seabird ecologist on the island next spring .

Of particular interest will be the many caves on the island and in the offshore waters, which are believed to be frequented by Great White Sharks because of the abundance of food that can be found. The landside caves will also be investigated to search for more evidence of ancient human occupation.

Finding Salisbury spokesperson, Shelley Payne, said the outcome of the expedition would enable management methods to be developed to better protect the island's rich values.

She said the drone technology would be used to survey seabird nesting sites as well mapping the island's vegetation. A  sidescan sonar will map the underwater contours to develop a picture of what the island was like when sea levels were lower.