SURG volunteer divers recently conducted sea urchin surveys at four sites in the Solitary Islands. As the covid restrictions have been easing and space on the dive boats became more available, the members decided it was time to hold a subsidised dive or two, so the year wouldn’t end without at least a couple of organised SURG dives. Casting around for a project, so their time underwater could be utilised productively, it was bought to SURG’s attention the possibility that two urchin species found in our area were hybridising, Tripneustes kermadecensis and Tripneustes gratilla, (follow the link to the species page in the Species Index).


With the generous help of Dr Maria Byrne and Dr Brigitte Sommer from the University of Sydney, a survey protocol and photographic identification sheet were developed and the divers, who underwent some preliminary reading and familiarisation, were ready to proceed. On the 14th November, 10 divers took part in surveys at South Solitary and at South West Solitary Islands where 5 transects were completed. Each transect is 2 m wide by 25 metres long, and every urchin found within that area is identified and the numbers recorded on underwater paper. Photographs were taken of any suspected hybrids, plus any where the identification was suspect, for further evaluation. The following weekend 6 divers using the same protocols conducted 4 surveys at North and North West Solitary Islands. Theresults of all surveys were collated, the photos downloaded and all the data has been forwarded to Sydney.

SURG subsidised dives couldn’t take place without the generous support of the members, who contribute a substantial amount of the cost out of their own pockets, and the two local diveshops, DiveQuest from Mullaway and Jetty Dive from Coffs Harbour who allowed SURG a reduced rate for the bulk booking.

Tripneustes gratilla

Tripneustes kermadecensis

SURG divers Neil Vaughan, Ian Shaw, Karl Schulz, Jade Fredericks, Bruce Gilchrist and Daryl Wong.