Mammal Week 2019 - Cetaceans

The ocean’s deepest secrets – my time with beaked whales

by Frazer Coomber

Since I started work as the Mammal Society’s Science Officer, I have been working across a variety of British mammals from moles to mink and seals to shrews. However, my passion, experience and long-term interest has always been with marine mammals. One particular whale, the Cuvier’s beaked whale, I have spent many a long, hot, sweaty and tiring day trying to study this fascinating but often elusive creature.

So I am not going to wrap this species up in cotton wool but let’s just say that it is not the prettiest of cetaceans. It does not have the striking colours of killer whales, the shear awe-inspiring size of blue and fin whales or the speed and grace of the smaller dolphins. What it does have is a protruding lower jaw, two small pointy teeth (in adult males), skin that is raked and gnarled with scars caused by years of fighting with each other and a swimming behaviour that is slow, unobtrusive and easily overlooked.

So why do I find this species so interesting? Well you don’t have to be pretty if you spend the majority of your life in the deep dark depths of the ocean. Cuvier’s beaked whale has the record for the deepest (2992m) and longest (137.5 min) dive of any mammal! Quite a feat on one lungful of air. As a scuba diver I understand the effects of pressure and being underwater but the pressures that this animal routinely experience are immense.

How do they find and catch food in almost total darkness? How do they interact with each other? What do they do and where do they go? How many of them are there? And even questions like how long do they live for? This is a species we know very little about and probably why they are classed as data deficient under the IUCN classifications. What we can understand about this animal is often gleaned by short observation periods as it surfaces, usually between two to three minutes. Or from the sounds that they make in the deep dark depths as they search for squid.

During my doctoral candidacy I worked for four years studying this species in the Mediterranean, a subpopulation classified as vulnerable by the IUCN, with the CIMA research foundation. Over summer I would spend many long days scanning, what often appeared to be an empty sea, on board a research vessel looking for these elusive mammals. Then at the sight of a slow arching back in the distance it all of a sudden became frantic action stations. Within the space of a few minutes we would try to get a quality photograph to identify individuals from their unique scarring patterns. Knowing that if we didn’t get the photograph we could be waiting floating on the sea for anything up to and sometimes over 70 minutes as they dived back to the depths. During this time, I had many wonderful encounters with this species with them sometimes inquisitively approaching the boats to see who we were and what we were doing.

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