26.08.2025 – Squid game Vol. II

Mid- and late summer are always particularly interesting times for whale-watching, particularly when it comes to toothed whales (Odontoceti). The summer sun warms the upper layer of the water column, leading to more intensive stratification, or layering, and forcing more deep sea animals to migrate to shallower waters during the night to gain access to nutrients trapped at epipelagic or surface layers.

This is especially true for several species of squid here in Madeira, particularly the Potas or Orangeback squid (Stenoteuthis pteropus). These cephalopods typically migrate to epipelagic layers at night to feed and then descend back into 800-1200m depths in the morning. At night, fishermen as well as marine predators such as dolphinfish, tuna, sharks and cetaceans gorge on these abundant deep-sea dwellers.

Apart from the popular squid eaters like Short-finned pilot whales (Globicephala macrorhynchus) and Sperm whales (Physeter macrocephalus), the different squid species also attract a number of smaller cetaceans like Bottlenose dolphins (Tursiops truncatus), Striped dolphins (Stenella coeruleoalba) and Atlantic spotted dolphins (Stenella frontalis). All these cetaceans were sighted during todays tours, four of them even during our spectacular morning tour which simply underlines how much diversity can be associated with such an abundance of deep sea prey.

Sadly, the deep sea is also a collecting basin for much of the contaminants that enter our ocean, many of them being toxic heavy metals and micro plastic. These toxins then bioaccumulate in larger predators feeding on the abundant squid, including cetaceans. This sad reality is a wake up call for all those who forget the importance of the deep sea, a habitat which is undoubtedly decisive for the marine life in Madeira.

By Paula Thake

Sightings of the day

Ribeira Brava

09:00 Short-finned pilot whales

13:00 Bottlenose dolphins, Short-finned pilot whales

16:30 Bottlenose dolphins

Stenella

09:30 Atlantic spotted dolphins, Short-finned pilot whales, Sperm whales, Striped dolphins

13:30 Bottlenose dolphins, Short-finned pilot whales

16:30 Bottlenose dolphins, Short-finned pilot whales