The Crown-of-Thorns starfish (COTS) is one of the primary health threats to the Great Barrier Reef (GBR) – reproducing in great numbers and feeding only on live coral, an outbreak of the starfish can strip a reef bare in weeks or even days.
Data gathered from the Association of Marine Park Tour Operators (AMPTO)’s Crown-of-Thorns Control Program by Project 2.1.1 indicates that investing in COTS surveillance efforts is just as important as culling the starfish.
Project 2.1.1’s team, led by Dr David Westcott at CSIRO, found that if COTS vessel control crews committed some of their seven-strong diver teams to surveillance operations, they would remove more COTS than on voyages where all divers were used on direct control (culling) actions.
Mixed surveillance-control teams would remove an average of 35% more COTS per voyage than control-only teams.
In the recently released report Strategies for Surveillance and Control: Using Crown-of-Thorns Starfish management program data to optimally distribute management resources between surveillance and control it is suggested that adding extra control divers to a mixed surveillance-control team could further boost this take rate up to 57% above the baseline.
Project co-investigator and senior researcher Dr Cameron Fletcher said more surveillance activities to identify the control areas with the highest ‘catch per unit effort’ (CPEU) would maximise control efficiency.
“What it comes down to, is that we need to be sure we’re dropping divers in locations where they have the biggest effect on COTS impact on coral,” he said.
“Surveillance is important because COTS tends to distribute in aggregations – if you can find these aggregations using surveillance then you can put your control divers in the water at the locations where they will be taking out COTS as fast as possible instead of swimming around looking for them.”
Surveillance dives, in addition to acting as reconnaissance for the control, also feed invaluable data back to researchers, including on the numbers and size of COTS, distribution and movements of outbreaks.
This will help shape future control efforts with a view to fully protecting the Reef from these voracious creatures, which are responsible for up to 50% of total coral loss on the Reef in recent decades.