Sweatman et al. 2008:

"The percentage of reefs on the GBR with outbreaks of COTS has fluctuated but has been declining as the third wave of outbreaks fades: there were Active or Incipient Outbreaks on 6% of the 104 reefs surveyed in 2006 and on 4% of 89 reefs surveyed in 2007. The highest percentage of reefs with Active or Incipient Outbreaks recorded in the 21 years of surveys was 17%, recorded in 1987, 1999 and 2000.

The overall density of COTS on the GBR shows a similar pattern. The overall mean number of COTS per tow was 0.13 in 2006 and 0.04 in 2007. This was lower than in 2005 when the overall mean was 0.14 COTS per tow. For comparison, the highest overall number of COTS per tow on the GBR during the last major wave of COTS outbreaks was 1.17 in 1988.

Details of the recent distribution of COTS are as follows:

• The numbers of reefs with outbreaks and the densities of COTS decreased in the Townsville, Pompey and Swain sectors between 2005 and 2007 and no Active or Incipient Outbreaks were recorded in these sectors in 2007. This is the first time that no outbreaks have been recorded in the Swain sector since surveys began in the mid 1980s.
• There were Active or Incipient Outbreaks on several reefs in the Cape Upstart sector and one reef in the Whitsunday sector in 2007, probably representing the extent of the southward drift of the third wave of outbreaks that was first seen near Lizard Is in 1993.
• Average densities of COTS increased slightly on reefs in the Cape Grenville sector and there was one reef with an Active Outbreak in the Princess Charlotte Bay sector in 2006, but these sectors were not surveyed in 2007.
• There were no significant changes in COTS densities within the other six GBR sectors."  

Citation and/or URL

Sweatman, H., Cheal, A.J., Coleman, G.J., Emslie, M.J., Johns, K., Jonker, M., Miller, I.R. & Osborne, K. 2008, Long-term monitoring of the Great Barrier Reef: status report 8, Australian Institute of Marine Science,  Townsville, Australia.

 http://www.aims.gov.au/docs/research/monitoring/reef/reef-monitoring.html

Spatial Coverage

 All of the Great Barrier Reef Marine Park 

Temporal Coverage

Manta tow surveys: 1986 to present

Intensive coral reefs surveys: 1993 to present

Update Frequency

 Initially every year but every two years since 2005

Other Information

 None