25.08.2024 – A plastic world

Today’s sightings were breathtaking, including Short-finned pilot whales (Globicephala macrorhynchus), Bottlenose dolphins (Tursiops truncatus) and Rough-toothed dolphins (Steno bredanensis). The morning was particularly interesting, as it demonstrated  ways of human impact on the oceans. The boats set off in calm seas, our guests were in excellent and excited mood. We passed a fishing boat and made a brief stop as the fishermen were just pulling in the lines. They had caught black scabbardfish (Aphanopus carbo) from depths of about 1500 m. A depth too great for many dolphins – but being as intelligent as they are, our resident Bottlenose dolphins have learned to approach as soon as the catch is pulled to the surface and grab a bite or two. Also this morning we found a small group of them near the fishing boat and were able to catch a glimpse of this amazing interaction.

Later, our spotter guided us to a group of enchanting Short-finned pilot whales. Only one individual looked odd – smaller, dark grey in colour, with a short beak… Another bottlenose dolphin right beside the Pilot whales! We get to see these mixed groups on rare, lucky occasions. Our passengers’ eyes were mostly focussed on the large pilot whales swimming calmly nearby, until the Bottlenose dolphin picked up a bright blue plastic bag, carrying it on his dorsal fin. Fortunately, in this case, the dolphin seemed unharmed and able to shake the bag off at any moment. But let’s not forget that plastic is ubiquitous. Plastic is all around. We use plastic every day. There is not much way around it when grocery shopping in the supermarket. As you made your way from the parking lot to our shop to start your tour, you might have seen some plastic rubbish lying on the ground. You might have spotted some floating in the ocean during your trip. New studies from our local research institutes show that deep diving cetaceans, just like Pilot whales, could potentially ingest plastics by mistake. They hunt in the depths via sound waves, and some plastic reflects the sound waves just as their favourite prey, the squid. Other studies measured plastic pollution in Madeira’s surrounding ocean, in Sea turtles, Seabirds, fish and squid stomachs and even fat samples of resident dolphin species which we observed today –  Plastic is everywhere. 

Have you tried to reduce plastic consumption in your daily life or when shopping? Have you picked up plastic from the ground, even if it is not your own rubbish? You have surely all heard it a million times – Reduce. Reuse. Recycle. Hopefully, our marvellous ocean encounters have helped to open our eyes and minds and to do things a little differently tomorrow.

by Sarah Kather

Sightings of the day

Ribeira Brava

09:30 Pilot whales, Bottlenose dolphins

13:30 Bottlenose dolphins, Rough-toothed dolphins

Stenella

09:30 Pilot whales, Bottlenose dolphins

14:00 Bottlenose dolphins, Rough-toothed dolphins

17:00 Bottlenose dolphins, Rough-toothed dolphins