A ground-penetrating radar survey has identified 12 additional potential burial sites on Wadjemup / Rottnest Island.

The survey, along with anthropological and archaeological work, was conducted following the discovery of human remains consistent with Aboriginal ancestry earlier this month.

Known culturally as Baalang, the remains were found adjacent to the main bus stop, on the hill of the Holy Trinity Church; a location not previously considered a burial ground.

Since the initial discovery on April 8 — which occurred during construction works to expand the island's main bus stop — Rottnest Island Authority (RIA) and Whadjuk Aboriginal Corporation (WAC) have collaborated to ensure cultural protocols are followed, and that respectful decisions are made regarding the protection and ongoing management of the site.

A WAC spokesperson said the situation "is deeply saddening, but it is not surprising".

"What is being uncovered on Wadjemup confirms what mob from right around the state have always said: the island is a site of widespread burial," the spokesperson said.

"The long-standing colonial narrative that burials were confined to the Quod burial ground is wrong. Our ancestors are across this island.

"Men and boys taken from Country, imprisoned, and buried in unmarked graves. This truth can no longer be ignored."

Following the discovery, WAC and RIA met with senior Whadjuk Elders and respected Aboriginal representatives on April 13 to seek advice on the appropriate cultural process moving forward.

At the meeting it was agreed an anthropological and archaeological survey should be undertaken to provide further cultural and historical context, as well as a ground-penetrating radar (GPR) survey of the works site to identify if other burial sites were present.

The GPR survey identified a further 12 potential burial-like anomalies at the location, WAC said, with additional archaeological investigation required before the burial sites can be confirmed.

Whadjuk Noongar monitors will continue to oversee the site.

WAC said it and the RIA will come together with senior Whadjuk Elders and respected Aboriginal representatives on Friday to be briefed on the findings, and to determine next steps.

"Whadjuk Aboriginal Corporation is committed to truth-telling and to ensuring Wadjemup is recognised and protected as the significant cultural landscape it is," a spokesperson said.

"We will work with the Rottnest Island Authority and the State Government, but this process must be led by Whadjuk people, guided by our Elders, and grounded in cultural authority."

From 1838 to 1931, colonial authorities used Wadjemup as a prison for Aboriginal men and boys. Nearly 4,000 were held in appalling conditions and hundreds were buried there.

Bibbulmun Noongar woman and human rights law expert, Dr Hannah McGlade, told National Indigenous Times Wadjemup is "a really deeply spiritual place, and we have to treat our ancestors with the utmost respect, because we've always believed that their spirits live on".

"We know that these men died on this island in very shocking, cruel circumstances, taken from their countries and families, and very few survived and made it home."

RIA and WAC said they recognise the profound cultural and spiritual significance of Wadjemup to Whadjuk Noongar people and the broader Aboriginal community.

The organisations said they "acknowledge and express our deep regret for the significant distress this incident and subsequent investigations has caused Aboriginal people".

WAC is encouraging Aboriginal community members to reach out to their office or their local Aboriginal Corporation for support and information.

"Whadjuk Corporation will rightfully work with mob from right around the state and keep them informed of activities and developments on the island - recognising that our men buried at Wadjemup come from right across WA," they said.

"This is a moment for honesty and action and we will ensure our ancestors are treated with the dignity and respect they deserve."

More to come.