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Blue Whales and Hammerheads in the Coral Triangle

By Morrison Mast

As the 130-foot schooner El Aleph plied the waters between the outer and inner arcs of the Maluku islands, Benjamin Kahn, cetacean researcher and founder of partner organization Planet Deep, addressed the guests aboard. He informed us that we were entering the world’s deepest enclosed sea, with waters as deep as 4 ½ miles. We were only a couple hours out from our port of embarkation, yet the ocean floor was already a deep abyss, some 18,000 feet below the El Aleph’s hull.

Thus began our Banda Sea: Reefs, Blue Whales, and Hammerhead Sharks expedition, a program that had been years in the works and represented a one-of-a-kind collaboration between Oceanic Society and Planet Deep. Beyond snorkeling on the Coral Triangle’s world famous reefs, our focus would be on the blue whales (Balaenoptera musculus) that are found in relative abundance in this sea, as well as the schools of endangered scalloped hammerheads (Sphyrna lewini) that occur here in predictable areas at the edge of volcanic islands. The intimidating depth of these waters is the very basis of this expedition—nowhere else on the planet would you find such prolific shallow-water reefs next to some of the deepest bodies of water in the world, a unique oceanic geography which brings these two iconic ocean species to the same area.

Over the course of 12 days, we would travel over 750 nautical miles on the El Aleph; first from the port of Saumlaki out to Hammer Island, then eastward following a chain of islands that comprise the “inner arc” of the Banda Sea. Our goal was to utilize our snorkel expedition as an opportunity to gather observations of marine mammals in this important yet understudied region. Before arriving to our final port in Maumere, our group would have positively identified 12 different species of marine mammals and witnessed schooling hammerhead sharks and a multitude of other marine wildlife.

This expedition is particularly unique because of its dual focus—part of each day is spent on the El Aleph’s observation deck scanning the horizon for the telltale blows of dolphins and whales, and the other part in the water, snorkeling and SCUBA diving. We were fortunate to have both of the founding members of Planet Deep on board throughout the expedition. Planet Deep is a newly-formed Indonesian non-profit organization that enables scientific research to occur in conjunction with conservation tourism in the Coral Triangle—the global epicenter for marine biodiversity. Co-founders Benjamin Kahn and Johannes Hennicke brought to bear both scientific expertise and a deep knowledge of the area. In addition, experienced divemaster and Oceanic Society naturalist Dalton Ambat has logged thousands of dives in this part of the world and was quick to find and point out notable species during dives and snorkeling outings. “This place is like our backyard,” commented Kahn, who has worked throughout the Coral Triangle region for decades.

But even for veteran travelers in this area of the world, the initial part of our voyage brought us to places about which little is known. Zooming in on the digital nautical charts of our location on a tablet, we noticed that the charts did not have enough resolution to display hydrographic features at lower scales, and a warning message reading, “mariners practice extreme caution, area uncharted” appeared on the blank part of the map.

In addition to the blank spaces on the map, Benjamin informed us that relatively little is known about marine mammal populations and movements in the area. “We know that these blue whales will migrate up from the western coast of Australia to the Banda Sea, but we don’t have a great idea of what exactly they’re doing here” said Kahn. “The information collected on conservation travel programs like this can greatly assist in filling some of these large data gaps.”

When not snorkeling, we would be on whale patrol. Like modern-day, well-meaning versions of whalers, the travelers, naturalists, and researchers aboard would attentively watch the horizon from as early as sunrise. When a spout was spotted, the spotter would yell “blow!”, and a large brass bell would be rung to alert the rest of the boat that we had spotted a marine mammal. Excitement would rise, and with binoculars and telephoto lenses trained on the location of the animal, the identification process would begin.

“Cetacean identification is a process of elimination. We start with an unidentified marine mammal, and then use identifying features to determine what it is not, rather than jumping all the way down to the species level,” said Benjamin Kahn. As the researchers and travelers identified and photographed our subjects, the captain and crew deftly maneuvered the boat at a crawl to put us in a prime viewing position that did not disturb the whales or dolphins we were observing.

Our first blue whale sighting came early on, between Saumlaki and Hammer Island. Rachel, a trip participant and graduate student in marine science from the University of San Diego, spotted a column of sea spray on the horizon, which was positively identified as that of a blue whale by Kahn. This was in a particularly deep part of the Banda basin, and the sighting was logged as a positive ID on a blue whale.

The most memorable whale sighting for many of the passengers came on the morning of September 13th off the north coast of Wetar. The distinctive blow pattern of a sperm whale (Physeter macrocephalus) was spotted in the distance, and Johannes Hennicke, Cruise Director for El Aleph, immediately asked the captain to change heading to get a closer look. As we slowly approached the whale another surfaced within 150 meters of the ship and Hennicke quickly gave the order to turn and put the engine in neutral. We watched in awe as the ship idled alongside this large female sperm whale, approximately 30 feet long. The whale rested at the surface, taking multiple breaths before arching her back and, with a final lift of her flukes, disappearing into the clear, dark water below.

The unique bathymetry of the Banda Sea creates a dynamic range of ecosystems throughout the inner arc in which multiple species of cetaceans can be found. When passing near a large underwater seamount on September 12th, our travelers had the rare opportunity to see a group of Cuvier’s beaked whales (Ziphius cavirostris), a deep diving and elusive species of whale. Very little known is known about this species’ ecology and biology, so to see them at sea was an unforgettable experience. Thanks to the photos from one of the travelers, Kahn was able to positively identify these rare cetaceans.

In addition to our whale patrol, Oceanic Society travelers spent multiple hours daily in the water either snorkeling or SCUBA diving, exploring shallow reefs full of life. From the very first day, the snorkelers and divers on this trip were treated to the vibrant display of marine life that can only be found in the Coral Triangle. Snorkelers didn’t need to go far to find octopus, abundant schools of reef fish, and vibrant hard and soft corals. The free divers among the group were free to explore steep walls teeming with life. One highlight was a large cuttlefish near the island of Romang, which displayed a hypnotic, dynamic skin coloration pattern as it hunted.

There is a reason this part of the world is known as “The Amazon of the Sea.” The Coral triangle is home to 76% of the world’s species of coral—the highest diversity in the world. Fifteen of those species exist nowhere else in the world. 37% of the world’s reef fish species call the Coral Triangle home, along with 6 of the 7 species of sea turtle.

Those among us who chose to dive experienced diverse marine habitats, from shallow, white sand plains dotted with cautious garden eels, to near-shore coral reefs, to steep volcanic drop-offs. In the latter, four-foot-wide barrel sponges at 100-foot depths embroidered with long, pale sea cucumbers protruded from a sheer wall that towered a hundred feet above us, and below us plunged out of sight to unfathomable blue depths.

It was in these unique settings that both the snorkelers and divers of the group were able to glimpse a multiple of scalloped hammerheads, a wildlife spectacle that occurs in only a few known places on Earth, and which was another focus of this expedition. It took multiple attempts and patient blue-water snorkeling outings over the course of our initial days before all were able to see them, but thanks to the blessing of a local community leader, the sharks revealed themselves on our last day at the anchorage of Hammer Island.

The tectonic dynamism of this part of the world was ever present, from the stratovolcanoes that dominated the distant outlines of the islands we sailed past, to gas bubbling out of cracks in the reef of Pantar Island. When in search of hammerheads, a small group of us experienced a long and very loud rumbling, which sustained itself for a full two seconds. Since this was an island where local fishermen prohibit the destructive practice of dynamite fishing, we determined that this was most likely due to volcanic activity.

As we neared the end of the trip and approached our final anchorage of Maumere, we were treated to even more species of cetaceans including pygmy killer whales, false killer whales, and a megapod of melon-headed whales near the Strait of Pantar. One of our final afternoons was spent in the shadow of the volcano Lewotelo, with the sun setting against the slope of the volcano.

Beyond the spectacular show put on by the ocean wildlife we experienced, the kind and dedicated crew of the El Aleph made everyone’s experience on board the ship extremely memorable. We hope this represents the first of many collaborations with Planet Deep in the Banda Sea, and look forward to returning to contribute further to research efforts in this truly awe-inspiring part of the world.


Morrison Mast is an Oceanic Society naturalist and special projects manager, and has devoted his career to wildlife conservation and education. Morrison holds a dual B.S. in Biology and Environmental Policy from the College of William and Mary and is a U.S. Student Fulbright Scholar.


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