05.10.2018 – Tunas and more

We never know what we might find out on the ocean before starting a tour. Clearly, our aim is to observe cetaceans but sometimes also other marine creatures provide great sightings. All encounters of the day comprised Atlantic Spotted Dolphins (Stenella frontalis), Striped dolphins (Stenella coeruleoalba), Bottlenose dolphins (Tursiops truncatus), Blainville´s beaked whales (Mesoplodon densirostris), one jumping Cuvier’s beaked whale (Ziphius cavirostris) and Loggerhead turtles (Caretta caretta).

But apart from this, one special highlight of the day has been the observation of Skipjack tunas (Katsuwonus pelamis) on the hunt. The first indication of this event have been circling and diving birds, mainly Corey´s shearwaters (Calonectris borealis) and gulls (Larus spec.). Such an activity in the air is usually a good sign for dolphins chasing fish but this time there have been other hungry predators around.

While taking a closer look at the scene an intense fishy smell was detected. Mackerels (Scomber colias) could be seen jumping out of the bubbling water. We observed shearwaters swallowing big specimens and could see plenty of Skipjacks approaching the shrinking swarm of mackerels for every direction.

Those fast-swimming pelagic fish can grow up to 1 m in length and weigh more than 10 kg. They are opportunistic hunters and can be distinguished from other tuna species by the silver coloration with several dark lines along the flanks. Definitely a remarkable sighting of a specie in the middle of the marine food web.

by Jan-Christopher Fischer

Sightings of the day

Ribeira Brava

10:00 Bottlenose dolphins, Blainville´s beaked whales

14:30 Blainville´s beaked whales

Stenella

09:30 (Snorkeling) Atlantic Spotted Dolphins, Striped dolphins, Bottlenose dolphins

15:00 Blainville´s beaked whales, Cuvier’s beaked whale, Loggerhead turtles, Skipjack tuna