COTs - N.W. Efate Frontal line, Report #2

 

Last Sunday we had 6 divers in the water doing 2 dives each, comprising 2 staff from Big Blue Dive, a Pele Island diver, French & Aussi volunteers and 1 x Sailaway diver.

 

We concentrated on the area found last week between Paul's Rock and the coastline, between 8 - 15 m depths, and up to 150 m offshore.  We found some aggregations where they were really thick on the ground, with many in hiding (or resting up) during daylight hours under shelves  or plate corals.

 

First dive at:   Lat 17 deg 39.91 min;  Long 168 deg 11 min,  we collected 286 COTs in 22 flour bags.        Lunch and a 2 hour surface interval followed.

Second dive at:  17 deg 39.88 min;   168 deg 10.99 min,     we collected 338 COTs in 26 flour bags.       Total for the day = approx 620 COTs, which were taken ashore.

So,  in 2 working days we have removed over 1000 COTs , such that an area of 200m radius is now almost clear.

 

Our radius at this second anchorage extended out 150 metres  and it could be seen the Frontal Line had moved further Northeast    and in 15 m depths could  in fact be closer to Mangaliliu Village than we previously thought, even though snorkelling on the fringing reefs out from the Survivor Beaches shows no sign of COTs as yet.

 

Next Sunday, we shall move our anchorage further NorEast to better define the Frontal Line  and then work back from there to SouthWest.

Any volunteers are welcome to join us.  We look to be making a difference, but realise the effort must be continued well into the future, to be effective.

 

Interestingly, Big Blue Dive have noticed that in areas of Mele Bay which had heavy concentrations of COTs say 2 years ago, that there is now an increase in opportunistic Drupella sea-snails which move in  after a COTs outbreak and mop up any remaining live corals.    In the past 30 years, we have never had a problem with  snails on Vanuatu reefs, although on the GBR   Drupella snails had been a big concern to Reef Check  (& possibly still are?)

 

We are still not sure what chemical would be most cost effective to kill spawn-water collected in the bilge of the dinghy, but expect Ammonia or Bleach would be suitable as it can be injected into COTs  to kill them,  and the NH3  is environmentally friendly, breaking down into salts in seawater.

 

Next Sunday,  we shall be leaving on the sandy bottom at 15 m,   about 10 NEW unholy  flourbags filled with COTs, totally sealed off so spawn can't escape.   Big Blue Dive have found that after a week, the COTs have died from starvation and the residual spines and guts can be released into the water, where fish can pick at the remains.   We shall be looking for any release of spawn from the bags when opened up on the following Sunday.

In the next few weeks, we hope to give you a series of U/W photos of this Big Blue technique, as employed in the past in Mele Bay.

 

Cheers,  Peter @ Sailaway.

Tel:  23802;  7723802

 

 

 

 

 

white scars indicate where COTs have moved through

 

 

 

 

Some pockets of competitive behaviour for the tastier morsels.  Not sure who gives right of way here ....

 

 

 

 

 

Filling flour bags, about 13 biggies / bag, before taking them to the surface

 

 

 

 

3 bags Going up !   This is a heavy lift, so adequate BCD buoyancy is helpful.           U/W photos:  Aurelien Garreau

 

 

 

 

Sunday 18 Nov 2012  COTs team #2:     Willie (Pele Is.);  Toby  (Oz volunteer);  Aurelian  (French volunteer);   & Big Blue divers from Mele =  Wills & Luaky.       Photo:  Peter (Sailaway)