Shark outlined in living light
I read Norm Fraser's interesting account of extraordinary bioluminescence ("Mariner notes exciting bioluminescent display," Issue No. 88), and wanted to relay a similar experience. This one, however, had the hint of a solution to its cause.
We were aboard Gesina, our SW48 yawl in the Ensenada Malacul, the first bay in the beautiful Puerto Mochima near Cumaná in Venezuela. It is a protected bay in a large national park.
Late one moonless, starry evening around New Year's Eve, while anchored in about 20 feet of clear water (with four of the major planets strung-out like a necklace above us), we noticed luminescent pockets all around us. In a random pattern, they would spring to life, glow, and then die-out. We also began to sense that there was often a rippling of the surface that seemed to coincide with the birth of some of the pockets. The sound was like that of a fish breaking the surface.
We concluded that the luminescence was the result of fish disturbing the phytoplankton around them as they either fled from a predator or fed. We soon got a strong confirmation of that theory. We were standing in the cockpit of the boat, watching the show, when we noticed a particularly large patch of luminescence develop about a boat-length ahead of the bow, but well off to starboard. The patch then began to move toward us, and it glided soundlessly not more than five feet off the starboard side of the boat, traveling from bow to stern and toward the mouth of the bay. As it passed, we could see the clear, green-glowing, full image of what appeared to be a large shark, about five feet long. Its outline was very distinct.
The image moved in a sinusoidal motion as it passed. Especially noticeable were the shape of a broad head and the pectoral fins. The glow tapered toward the rear, but then had an extra burst of luminescence at the tail. It was an awesome moment. The bioluminescence died out almost totally after the animal's passage.