13.09.2018 – One off the bucket list

After our crew and guests on our traditional saw Bottlenose dolphins (Tursiops truncatus) and Striped dolphins (Stenella coeruleoalba) in the morning and the impressive Cuvier’s beaked whale (Ziphius cavirostris) at midday, I was excited to see what surpises the Atlantic had in store for us on the Stenella in the afternoon today.

Around 4 nautical miles off Jardim do Mar our spotter saw a group of birds circling an area. As we approached the location, we were able to see a large shoal of dolphinfish (Mahi mahi) swimming at the surface near our boat. As we maneuvered around to continue observing the fish, one of our guests, Sabine Opitz, suddenly exclaimed and pointed at a large shadow in the water. I immediately recognised the species because I’ve been wanting to encounter one for as long as I can remember. The white spots covering the beautiful 8m long giant, dark-grey body instantly gave it away; it was a Whale Shark (Rhincodon typus).

The Whale shark is a slow-moving, pelagic species of shark that inhabits the tropical and warm-temperate waters of our oceans. They belong to the cartilageous fish or Chondrichthyes, a class that includes sharks, rays, skates, sawfish and chimaeras. Unlike bony fish, these animals all have a skeleton made of cartilage rather than bone and their skin is covered in dermal denticles instead of scales. Whale sharks have five large gills which they use to breathe and, like all carpet sharks, have additional spiracles to ventilate this respiratory structure. These sharks are ovoviviparous; meaning that their eggs remain inside the animals body until they hatch and the female then gives birth to live pups.

The irony and beauty of this sighting lies in the fact that we encountered the largest living non-cetacean during a whale-watching tour. Being sharks they have little in common with cetaceans save two characteristics; their size and their feeding method. The word „whale“ is often used as a descriptive term when referring to something large and actually means „large sea fish“, making the name quite fitting for this species, considering that the largest individual had a length of around 12m!! Moreover, like baleen whales, they exclusively feed on zooplankton and small fish. Whale sharks are amongst the three known filter-feeding shark species and feed through ram filtration or suction feeding. The animal uses its enormous mouth that can reach a diameter of up to 1,5m (!!) to swallow large amounts of water that are subsequently pushed out through the its gills. While ventilating the gills, its prey is separated and filtered along filter-pads through cross-flow filtration.

As with certain baleen whales, there are places in the world where whale sharks reliably congregate at certain times of the year to collectively feed on plankton and encounters with these gentle giants can be expected. Madeira is not one of these places; Whale sharks are rarely spotted around the Potuguese archipelago making this a sensational surprise for our team.

The reason why this blog is primarily about the Whale shark today isn’t only because I’m happy to tick an encounter with this incredible animal off my bucket list. These beautiful creatures are listed as endangered on the IUCN list and are still being illegally hunted and exploited for their fins, skin and oil in some parts of the world.  So, like with most large marine creatures, such sightings are not to be taken as given. Moreover, this was Lobosonda’s first ever encounter with a Whale shark, making the guests that were aboard this trip extremely lucky.

On our evening trip on the Stenella we tried to search for the animal again but couldn’t find it. Instead we had beautiful encounters with Short-finned pilot whales (Globicephala macrorhynchus), Bottlenose dolphins (Tursiops truncatus) and the rarely encountered Rough-toothed dolphins (Steno bredanensis). The animals were all sighted around the same location where we had previously seen the Whale shark, probably indicating that there must have been beneficial currents in the area. These sightings helped wrap up an overwhelmingly beautiful day for our team and is another humbling manifestion of the generosity of our daily host, the Atlantic ocean.

Note: There is added pictures, courtesy of our client Günter Seng 🙂 Many thanks 😉

By Paula Thake

Sightings of the day

Ribeira Brava

09:00 Bottlenose dolphins, Striped dolphins

13:30 Cuvier’s beaked whales

Stenella

15:30 Atlantic spotted dolphins, Short-finned pilot whales, Whale shark

18:00 Bottlenose dolphins, Rough-toothed dolphins, Short-finned pilot whales