This morning we ran two dives in a row, working through lunch to try to finish early. Each dive lasts one to two hours. The ROV is lowered over the side and remains tethered to the ship by two lines, one a bundle of 32 electronic cables in a thick plastic sheath and the other a simple ship's line. The cables attach to electronic equipment on the ROV, everything from its motors and lights to the communications and cameras. On this dive I help Glenn, one of the ROV pilots, as he tends the cables, clipping them together at regular intervals until the ROV reaches bottom.
The ridge we approach boasts more snapper and grouper than on previous dives. In the blue upper margins of the screen large pale fish swim away. Some hover at the limits of our sight, while others flee just after entering the field of view. A few remain still and seem uninterested in our approach. One of the fish we are most interested in, the gag grouper, is wary of the ROV and also seems to be uncommon, perhaps because they have finished spawning and begun to leave the area.
I try to learn some of the fish from Stacey and Andy, who identify most of the ones we see almost instantaneously based on the hundreds of hours of deep sea videotapes they have watched. Sometimes it's the silhouette or particular markings on a fish, sometimes it's the way they swim. For example, scamp are known for a broom-shaped tail.
After a few days I can appreciate some of the distinctions they make, but it's still impressive to see one of the quicker fish flash by for a second at an oblique angle yet still be recognized and recorded. On ridges with a gradual approach, we typically start on sand and swim through larger and larger stands of colorful sea fans with fish hiding places and orange and red encrusting animals underneath. In smaller crevices off the main ridge, the ground is flatter and we see fewer species, mostly those small enough to duck into the most meager of hiding places such as bigeye or bank sea bass. Under more dramatic ledges and on top of large promontories we find scamp, red grouper, small schools of creole fish, and lots of amberjacks whenever there is natural hard bottom around.
When we return to the sand there aren't a lot of fish, and people are impatient to reach the next mound or pinnacle. Marta, our GIS mapping expert, scrutinizes the map and predicts when we're likely to see more hard-bottom habitat. Long stretches of sand are punctuated with the occasional sea pen, a family of animals related to soft corals that look like a long feather sticking upright from the sand. In some locations they grow in dense forests, but here they appear only one at a time. Other highlights of the sandy bottom include the entertaining pink razorfish, perching on the surface until their disappearing act with a sudden dive into the sand.
The flying gurnard is one of the more unusual sights, a fish with pectoral fins on each side enlarged into wings that it uses to walk along the seafloor. We try repeatedly to photograph specific fish that seem to turn away just as their picture is taken, such wrasse bass in its appealing striped coloration. With all ROV operations the pilot has only a few seconds to maneuver, zoom in, or take a photograph before the deadweight and the ship begin to tug on its tether and it's time to move on.