A second crown-of-thorns starfish control vessel commenced operation on January 10 as part of efforts to protect Australia’s Great Barrier Reef health by culling coral eating crown-of-thorns starfish over the next three years.
Populations of crown-of-thorns Starfish (Acanthaster planci) have exploded in recent decades, causing huge impacts on the health of the Great Barrier Reef.
A single starfish can grow up to a meter wide and eat its own body weight in healthy coral in a single day, with the species believed to be responsible for up to half of all coral loss on the Reef.
Changing water conditions linked to coastal agricultural runoff and climate change are thought by scientists to be the main causes of outbreaks. An outbreak is considered to have occurred when there is roughly more than 15 starfish per hectare or more than one starfish spotted per 20 minute swim.
Dr David Wachenfeld from the Great Barrier Reef Marine Park Authority said: “The future of the Great Barrier Reef relies on a concerted effort to build its resilience. This work is part of a wider suite of measures taking place Reef-wide, regionally and locally to help the Reef bounce back from its worst bleaching on record.”
The focus to date by the first control vessel MV Hero has been on 21 key reefs that are either popular tourism sites or locations with strong currents that can spread outbreaks. These sites span 75 percent, or 940 square kilometers, of the reef habitat offshore of Cairns.
The second control vessel Venus II extends control efforts southward from Cairns to Townsville, protecting up to an additional 1,000 square kilometers of reefs. During its maiden voyage the vessel Venus II will target starfish control offshore Cardwell, including Rib, Trunk, Bramble and Little Kelso reefs.
The starfish are given a lethal injection by divers, and since its introduction, the control program has culled more than 400,000 crown-of-thorns starfish. Follow-up surveys show the culling has successfully protected coral cover and kept the adult crown-of-thorns starfish population to below outbreak levels in the Cairns region.
There have been four major outbreaks on the Great Barrier Reef since the 1960s (in the 1960s, late 1970s, early 1990s and 2010) and the time between the start of each outbreak has been 15–17 years. The fourth and current outbreak began in 2010.
The Australian Institute of Marine Science estimates the Great Barrier Reef has lost approximately half of its coral cover since 1985. The research attributed the loss to three main factors in the following order: cyclones, crown-of-thorns starfish and coral bleaching.
The Great Barrier Reef Marine Park Authority awarded the Reef and Rainforest Research Centre and the Association of Marine Park Tourism Operators a $5.6 million tender to operate the second control vessel. The vessel is being funded through the Australian Government’s $140 million Reef Trust.
A large amount of research on crown-of-thorns starfish is being undertaken by:
• Australian Institute of Marine Science
• James Cook University
• National Marine Science Centre/Southern Cross University
• Reef and Rainforest Research Centre
• University of Queensland
The long-term strategy is to protect live coral cover and the integrity of the ecosystem from crown-of-thorns starfish outbreaks. This involves understanding the causes of outbreaks and, if possible, trying to prevent them. It also includes early surveillance and detection to allow faster responses to outbreaks and to reduce their spread, with the ultimate aim of increasing the duration between outbreaks. This will give the Reef greater time to recover.