Growing concern surrounds the impact of illegal fishing on the Kimberley reefs in the state of Washington.

A senior marine scientist says the decline in sea cucumber populations on the Rowley Shoals in the northern part of the state is a cause for concern regarding global conservation efforts.

Key points:

• DBCA reports its staff have observed a decrease in sea cucumber numbers on the Rowley Islands.
• An environmental advocate says illegal Indonesian fishermen are endangering reef health.
• Border authorities say they have seen an increase in the number of boats this year.
• The Department of Biodiversity, Conservation and Attractions of Washington State (DBCA) announced last month that its staff had "unexpectedly" noticed a decline in marine life populations on all three reefs.

Sea cucumbers, or trepang, are a well-known target for illegal foreign fishermen from Indonesia who supply this commodity, as well as shark fins, to China.

Illegal fishing has long been a problem on the three islands that make up Rowley Shoals Marine Park and Mermaid Reef Marine Park.

There has been another surge in recent years.

Five men stand on the bow of a long wooden boat floating in ocean water. Environmental advocates who surveyed the reefs last month noticed six boats in protected areas. (Courtesy: Sophie Calkovski-Poup) Conservationists fear irreversible ecological damage to the pristine marine ecosystem if stricter law enforcement measures are not implemented.

Mermaid Reef is part of the Commonwealth Marine Reserve, while Imperieuse Reef and Clerke Reef fall under state jurisdiction.

"Baseline Conservation" Over the four months since July, Australian Border Force (ABF) data shows that almost the same number of illegal foreign fishing vessels have been intercepted as 12 months ago.

A total of 105 boats have been intercepted since July, and 125 for the entire 2022/23 financial year.

Senior marine science researcher at the University of Western Australia, Mark Meeuwig, said the impact of illegal fishermen on the populations of creatures like sea cucumbers on the reef should be a priority.

Smiling man in front of the camera with the beach disappearing in the background. Dr. Meeuwig says the Rowley Shoals are critical to global conservation efforts. (Courtesy: Mark Meeuwig) Dr. Meeuwig said the Rowley Shoals serve as a "critical starting point" in conservation, as they are among the last reefs in the Indian Ocean that are still largely untouched by human impact.

"If we're trying to help restore coral reefs, which are in crisis worldwide, we need to have a target to aim for," he said.

"Once [the Rowley Shoals] degrade, we don't have other measures that could tell us where we should direct our conservation goals.

"The Rowley Shoals are... the last that we have."

A large pile of small, slippery items in a dark storeroom. Sea cucumber or trepang catch seized by the Australian Border Force from an Indonesian fishing vessel. (Courtesy: Australian Border Force) Dr. Meeuwig acknowledged the long history of Indonesian fishing in the northern part of Washington State, but said that the demand for trepang and shark fins in China and other countries is making this practice increasingly unsustainable.

"All you need to do is look at places like Scott Reef or Ashmore Reef, where Indonesian fishermen have been fishing for centuries," he said.

"Ultimately, in diveable depths, there will be almost no sea cucumbers and very, very few sharks."

Dr. Meeuwig said the impact on food chains and ecosystems was "not just bad news; it's a tragedy."

Additional Monitoring Continues An ABF representative said the Australian Fisheries Management Authority (AFMA) is working closely with the Australian Border Force (ABF) to mitigate the consequences of illegal foreign fishermen.

"This includes regular aerial, ground, and maritime surveillance, targeted operations, and deployment of ABF and ADF ships," they said.

The representative stated that authorities continue to consider and explore options for patrolling and monitoring to detect and intercept foreign vessels operating illegally in Australian waters.

A man smiles in a small canoe in turquoise water. Illegal Indonesian fishermen are regularly seen on the Rowley Shoals. (Courtesy: Sophie Calkovski-Poup) A DBCA representative said recent environmental monitoring of the Rowley Shoals reefs has been expanded to include specific sea cucumber monitoring sites in response to their decline.

"[Monitoring] will provide a basis for better understanding the consequences of illegal fishing in the Rowley Shoals Marine Park in the future," they said.

Dr. Meeuwig said that the government needs to step up its efforts before it's too late.

"If we don't begin to much better enforce the marine protected status of these reefs, there won't be much left to protect," he said.