By Mark Bond
We woke up to the wind howling! Although the day’s rough seas prevented us from getting any of our Oceanic whitetip research done, there were still some surprises in store. One of the most exciting things about spending time on boats is that you never quite know what you will see.
With the weather forecast to deliver high wind for the next 4 days we decided to head up the coast in search of more protected anchorage. While we were trolling for pelagic fish to sample for stable isotopes, a rough and otherwise uneventful cruise up the coast quickly turned into a frenzy of excitement. The presence of diving birds on the horizon attracted our attention. When trolling, a successful technique for finding fish is to use birds to indicate where fish are in the waters below.
As we got closer to the birds the ocean suddenly began to boil with activity. We looked down from the bridge and a large, dense bait ball of fish was bubbling excitedly at the surface. Just like an iceberg, most activity of a bait ball occurs below the surface of the waves. When previously trolling we witnessed an oceanic whitetip cruising through a small school of yellow fin tuna so we eagerly scanned the water. Through the whitecaps we could see a dark grey shape below the frantic activity of the fish. At first I couldn’t decide what I was looking at – the opinion amongst the boat was divided. Unfortunately, whatever it was it dove deeper and disappeared from sight leaving us dejected and frustrated that we didn’t really know what we had seen.
Using the birds we chased the bait ball, now a few kilometers away, hoping that whatever we had seen was still following it too.
Once more the dark grey shaped loomed up from the purple-blue water, but this time it came closer to the surface as it searched for food. Almost in unison everybody shouted “whale shark!!” In truth, whale shark may have been preceded with a few expletives as the excitement at seeing something so rarely observed in the Bahamas overcame us. Captain Scott expertly positioned us alongside the school-bus-sized fish and we jumped in for a closer look. The whale shark was estimated to be 20 feet long, still a juvenile as the adults – the biggest fish in the sea – can grow to be 60 feet!
Although the whale shark was the star of the show, this was a unique opportunity to observe the ocean’s intricate foodweb in action. The cause of all of this commotion and the lowest in the pecking order were the bait fish. At the surface of the water just below the waves was a layer of finger-sized bait fish 6-10 inches thick and packed with individuals moving as one as they attempted to dodge the onslaught of predators. From above, the seabirds swooped and dove down on the bait fish, their presence being marked by the flurry of webbed feet we could see from under the water. From the below, the bait fish were being picked off by a school of skipjack tuna as they mirrored the motion of the seabirds but in reverse. It was the tuna that caused the bubbling effect we could see from the boat. Tuna, designed for high speed with their streamlined body-shape, frequently breach the surface as they rocket up from the deep to scoop a mouthful of prey.
Amongst all of these elements, the graceful whale shark made intermittent passes with what looked like barely a beat of her tail. Despite their large appearance, whale sharks are filter feeders and pose no threat to humans. They are well protected internationally, however they are still a target of illegal poachers for both their meat and their large fins for the shark fin soup trade. Their presence in aggregations around the world have developed an economically beneficial eco-tourism trade for many developing countries such as Belize, Mexico and the Philippines.
Still buzzing form our whale shark encounter we pulled the boat into the safety of the dock but the day was not finished yet. Under the dock was a manatee! Like the whale shark the Florida manatee is a species rarely observed in the Bahamas. The Florida manatee is also endangered and warrants protection. The removal of critical sea grass beds and boat collisions have left their numbers diminished in south Florida, their usual home. To get in the water with what can be a very skittish animal was a real treat. She did not seem phased by our presence and was so curious about what must have seemed to her to be these strange uncoordinated guests in her waters. It was proof that even when the weather decides to disrupt the best laid plans the oceans can deliver some unique surprises.