SE16-02: Re-Breather diving in Samoa; counting fish without bubbles

by Jamie Barlow

Team Redundant” is what we proudly call ourselves; we are the re-breather team on the R/V Steel Toe and silently dive with the goal to count and size reef fish.

Figure 1: Ray Boland and Tate Wester pose for a picture; all gear up, cameras in hand, and in moments will roll out of the boat to start their reef fish survey.

Figure 1: Ray Boland (left) and Tate Wester (right) pose for a picture; all gear up, cameras in hand, and in moments will roll out of the boat to start their reef fish survey.

For the next couple of weeks PIFSC staff and partner agencies will be working off of the NOAA Ship Oscar Elton Sette in the American Samoa archipelago. There are a total of 4 vessels tending divers and 3 of these small boats are covering as many sites within the day as possible.  We need statically enough to quantify abundance but in this 19’ SAFE boat warmly called “ R/V Steel Toe” we are diving on the same site twice…Why? one could very well ask… and the reason is that there is a notion that bubbles escaping from normal SCUBA systems (or “open circuit ”)  could bias fish counts because the noise the bubbles make could either attract or spook fish from the area being surveyed.

Figure 2: The divers will spend up to an hour hovering over the reef and counting fish. Notice the lack of bubbles escaping from Ray Boland’s re-breather unit.

Figure 2: The divers will spend up to an hour hovering over the reef and counting fish. Notice the lack of bubbles escaping from Ray Boland’s re-breather unit.

The CREP fish team is taking this “does SCUBA bubbles effect fish counts?” question head on with a comparative study. And so, re-breathing comes into the fold. The R/V Steel Toe visits 3 sites a day where a team of scuba divers and a team of rebreather divers survey the same site on the same day….. randomly deciding which method goes first at each dive site.

Figure 3: Andrew Gray preps himself for a 75ft re-breather dive. His CREP colleagues using SCUBA are just finishing up their dive , they will be on the surface momentarily and quick chat about the direction of current and the line angle is all he needs before he rolls in. This comparative study is looking to see if the fish he sees has any stastical difference to what his colleagues just saw.

Figure 3: Andrew Gray preps himself for a 75ft re-breather dive. His CREP colleagues using SCUBA are just finishing up their dive , they will be on the surface momentarily and quick chat about the direction of current and the line angle is all he needs before he rolls in. This comparative study is looking to see if the fish he sees has any statistical difference to what his colleagues just saw.

The “Team Redundant” nickname refers to the, thorough planning, extra safety precautions, backup safety equipment and a 16 action item checklist that each re-breather diver completes prior to each dive. This check list runs thru the opening of valves, checking of sensors and calibrating dive computers and when everything checks out; each diver dons their 75 pound re-breather and breathes off the unit for 5 minutes before rolling of the boat slate-in-hand.

Figure 4: Andrew Gray and Tate Wester thoroughly examine and check their re-breather units prior to each dive. They are in the middle of their 16 action item checklist; demonstrating safe and best practices for closed circuit diving.

Figure 4: Andrew Gray (back) and Tate Wester (front) thoroughly examine and check their re-breather units prior to each dive. They are in the middle of their 16 action item checklist; demonstrating safe and best practices for closed circuit diving.

As the Coxswain , I read off the their 16 action item checklist , but I have no idea what each action is, means or requires the diver to conduct. However I hear “check” from each diver before we move to the next item. It’s obvious to me that years of rigorous training and a careful, methodical and observant personality give each diver the edge they need to safely dive with re-breathers. However for Andrew Gray, Ray Boland and Tate Wester , or as they affectionately call themselves “Team Redundant”  this silent diving is just another effective methodology to count and size Samoa’s reef fish.

Figure 5: “Team Redundant” hard at work

Figure 5: “Team Redundant” hard at work

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