As noted above, the office of the Regional South Pacific Aquaculture Development Project agreed to support this survey. The author was contracted, based upon his private work with culturing commercial sponges for the past several years, to conduct a 21 day survey, surveying as many sites as possible within this time period. The survey began on September 4, 1988 and was completed on October 16, 1988. The survey was to be done using SCUBA diving techniques, two dives per survey day. The sites to be surveyed were recommended by the author and approved by the FSM office of Marine Resources. The sites were selected based upon how closely they matched the conditions, observable from the surface, of the one known commercial sponge bed - ie. close to a reef passage, mixed coral and sand, good clean water away from any rivers or streams and gentle sloping bottom.
Sites were selected all around Pohnpei. While each SCUBA dive lasted only about 45 to 60 minutes, only two dives were possible for most sites. Travel to the sites on the other side of the island took at least two and a half to three hours each way, while travel to the closer sites took about one half an hour each way. At least two to three hours were required for the surface interval between dives. Preparation time was required both before and after each trip. All in all, anywhere from six to ten hours were spent each survey day.
Each site was surveyed by two divers, using SCUBA equipment, a 19 foot FRP boat with a 30hp outboard motor, and where possible, was surveyed down to a depth of 65 feet. On the outward leg of the dive, one diver swam at a depth of 55 feet and the other diver swam at a depth of 40 feet. On the return leg of the dive, one diver swam at a depth of 30 feet, and a second diver swam at a depth of 20 feet. Using this method, reefs with a relatively steep slope could be covered completely, and reefs with a shallower slope would be sampled at all depths from 15 feet deep down to 65 feet deep. As noted in the site reports, some sites did not reach a depth of 65 feet, and these were surveyed to their deepest point.
All commercial sponges sighted during a dive were noted as to size and depth. However, as no calipers were available on the island and as shapes, in most cases, were very irregular, the sizes had to be estimated by the investigator. Depths were measured using a standard oilfilled depth gauge. All sites surveyed were noted as to potential sponge farm sites.
On the sites that did not bottom out at 65 feet deep, we were able to cover most of the area within that survey site. This does not mean, however, that we found every commercial sponge within that site. The sponges are hard to see, being black, and sometimes are found down within the corals, or growing under the ledges. This is even more true for the areas that did not bottom out at 65 feet or less. At these sites we were only able to make a large circle, noting what sponges we could observe. So in all probability, we did not find all the commercial sponges within any area.
Be that as it may, we did get a good sampling of the density of commercial sponges in each area, and this can be compared to the density of commercial sponges found within the known sponge bed. During any dive within the commercial sponge bed at least 35 to 40 sponges of commercial size, ie in excess of 14 inches, will be observed.
