28.07.2019 – The blue resilience

Everyone knows that the natural world on our planet is in peril and this impending doom doesn’t pick sides or favour anybody, not even human beings. The same applies to marine mammals. Despite their profound intelligence and learning abilities, dolphins and whales are very much victims of the way we treat our oceans. So much so that, even in the crystal-clear, comparatively sparsely trafficked and clean waters of the Madeira archipelago, we still bear witness to the unfortunate dangers faced by aquatic creatures on a global level. 

Plastic is undoubtedly the biggest culprit and a guaranteed sighting on every one of our tours. The countless cases of marine animals getting entangled, ingesting or getting poisoned by this versatile material along provide proof enough of how enormous and severe the problem actually is. The ocean ironically makes use of this deadly waste, with plankton hinging onto it and using it as a substrate for growth. While this enables the growth of many little crustacean colonies, little islands of life, it also bids other marine organisms such as marine birds like the Cory’s Shearwater (Calonectris borealis) or fish like the Atlantic Triggerfish (Balistes capriscus) to nibble and ingest poisonous micro plastic particles. Microplastic is what plastic erodes to over time and these minute particles are ingested by marine creatures and accumulate up the food chain. As with heavy metals, the highest concentrations are found in apex predators like cetaceans. Plastic is so poisonous that it is even known to cause stillborn births in different species of dolphin. This is why we always makes an effort to remove as much rubbish as possible during our trips out at sea, as we also did today.

Another problem is our exploitation of the oceans and this is a problem that has one of the strongest negative effects on cetaceans. A dolphin has acute learning abilities and that combined with their long-term memory can prevent them from nibbling on the same hook or a piece of plastic a second time. The short-term memory of sea turtles, like the Loggerhead turtle (Caretta caretta) means that it may not learn from its mistakes. Dolphins desperate for food, however, will get too close to larger fishing boats or even try to steal bait from fishing lines.  

Another challenge dolphins face is noise pollution, that even encourages deep-diving cetaceans such as beaked whales to remain underwater and not surface for air. Even the deepest of all mammals to our knowledge, the Cuvier’s beaked whales (Ziphius cavirostris) have washed ashore with internal injuries indirectly related to noise pollution. 

I apologise for writing about such an eventful day at sea with a lost of issues, but our team is confronted with problems which we cannot and will not ignore. To end this blog on a more positive note, apart from the above mentioned species, our sightings also included encounters with Bottlenose dolphins (Tursiops truncatus), Atlantic spotted dolphins (Stenella frontalis) and a group of Striped dolphins (Stenella coeruleoalba). Keeping and experiencing everything that is worth saving is central to us changing for the better and the charisma of dolphins, makes them flagship species in this ongoing struggle.

By Paula Thake

Sightings of the day

Ribeira Brava

10:00 Bottlenose dolphins

Stenella 

09:00 Atlantic spotted dolphins, Bottlenose dolphins, Cuvier’s beaked whales, Striped dolphins

12:00 Atlantic spotted dolphins, Loggerhead turtle