Back in the Gulf: Life Without Wings

May 13, 2011

Skipjack tuna

Birds are hardly the only marine life we see during this Gulf study. One morning out at sea I see a shiny, transparent piece of debris bobbing on a wave. Oh no, I think; it looks like plastic, of a size and appearance to pose a real danger to any sea turtles thinking to get an easy meal.

But it is entirely natural, a Portuguese man-of-war “jellyfish.” It has a body consisting of a translucent gas-filled, bladder-like float tinted pink, blue, or violet, part of which forms a crest which functions as a sail for drifting movement across the sea. Underneath this float is a cluster of polyps from which hang tentacles of up to 165 feet long. These pelagic colonial hydroids or hydrozoans are infamous for their very powerful, painful stings. One of the Gordon Gunter’s very own crew members was stung fiercely during a swim at the beach last week in Key West.

Our crew is fanatical about fish, and fishing. During daylight hours, we trail a line or two far behind the ship while it is underway, hoping to catch our lunch or supper. We are not disappointed. Mahi-mahi (also known as dolphin-fish or dorado) are our most frequent catch. The intense blue, yellow, and green colors of these predators are visible even when the fish is several feet below the ocean surface. In addition to those caught, it is not unusual to see two or three scattered around anything floating, a wooden board, a small plastic float, a patch of Sargassum weed.

Spinner dolphins

We also catch several wahoo, a torpedo-shaped member of the mackerel family highly regarded by many gourmets. Some wahoo have reached 8 feet in length, and weigh up to 180 pounds. Today we catch a small skip-jack tuna, a fish that schools up and roils the water during its feeding frenzies. And above those frenzies hover birds, numerous and diverse, hoping to seize a small fish being chased by the larger ones.

Although not tallied in large numbers, two of the three marine mammals we do see are species I’ve never seen before. In addition to the widespread bottlenose dolphin, we see a small pod of pan-tropical spotted dolphin, dashing in to playfully ride the bow wave of the ship. Compared to their larger cousins, the Atlantic spotted dolphin, the spots on this species are smaller, at times entirely absent, but their upper and lower jaws separated by thin white “lips” on their long beak confirm their identity. And one evening at dusk, another dolphin pod sneaks up on the Gunter from the stern. I notice a very long, erect dorsal fin, not as swept-backward as on most dolphins. Could it be? After one dolphin playfully breaches through the water, doing a double-axel role before splashing back down, there is no doubt: these are spinner dolphins, a species I have long wanted to see.

Leatherback turtle

Throughout our winter and spring surveys this year, we have seen very few sea turtles in the Gulf. But this day I am rewarded twice over. Not just one, but two huge leatherback turtles. This endangered species is the largest, deepest-diving, most migratory and wide-ranging of all sea turtles. Some leatherback turtles reach 2,000 pounds! One is so close to the ship that I can clearly see the large pink spot on the top if its head, each spot as unique and useful as our fingerprints for determining individual identity.