I was fortunate to have a role in documenting an exciting and unexpected behaviour for the 'COASTS' episode of Blue Planet 2. The behaviour is one involving a renegade band of Sea lions, who have carved out a niche for themselves hunting Yellowfin Tuna along the shores of Isabella Island, in the Galapagos.
Yellowfin tuna in the open ocean.
I have to admit, when I first heard about the behaviour, I was highly skeptical about the validity of the story, let alone the chances of being able to film it. It seemed fanciful to me at first - a fisherman's tale (literally, the series first learnt about it from a local fisherman). Of course Sea lions are adept, highly evolved hunters, but Yellowfin are fast - REALLY fast.
I'm glad to say that upon arriving in the Galapagos I was soon proved wrong, I got to witness one of the most amazing behaviours I've seen in close to 20 years of diving and working around the ocean. The amazing hunting success rate for the Sea lions comes down to a combination of their speed and agility, combined with cunning and strategy.
My role on the shoot was to document the spectacle from the air, using DJI Inspire and Phantom drones. The hope was that an aerial perspective on the event would reveal a side to the behaviour that was not possible to demonstrate shooting underwater or doing traditional long lens work.
Drones have revolutionised aerial filming in natural history documentaries (as well as in many other mediums). This shoot was a great example to me of how we were able to utilise them to document a behaviour that previously it would previously have been prohibitively expensive, or simply logistically impossible to film from the air. Being small, easy to transport, and relatively low cost, we were able to take a couple of drones with us and work effectively in an extremely remote location. A few years ago, imaging of the kind of calibre we have come to expect from BBC productions would only have been possible with a helicopter and Cineflex or other similar system. I'm not in the camp that believes that drones have replaced the Cineflex altogether (far from it in-fact), but they have made aerial imaging far more accessible and a part of our collective visual palette.
Our days on Isabella island started early, and we would set up on a viewpoint that gave us a good view of where the Sea lions would likely be herding the tuna back into the bay. Then we would sit, and wait. Like many natural history shoots, there was a lot of time spent in a condition of complete preparedness as we waited for the behaviour to start, all-the-while getting hot, uncomfortable and being pestered by the relentless flies that were attracted by the graveyard of tuna carcasses on the island. Here we would wait for what at times seemed like endless hours. When someone spotted a Sea lion finally porpoising into the bay (which we had learnt meant they were chasing in Tuna), everyone would begin yelling "ACTION, ACTION", and we would all spring into action as well. I would lay out strategically everything I needed for getting the drone into the air as quickly as possible, but no matter how prepared I would try to be, it would take close to minute to get the drone up and into position. Sometimes this would be too long and I would only get the tail end of the hunt, as the Sea lions focused on pinning the tuna into small coves. After many failed attempts, many many ours of waiting and a few tense moments where drones almost crashed due to firmware glitches, I managed to get into position quickly enough to film the Sea lions corralling the tuna from the open ocean - in towards the coast. What struck me, was how relaxed and controlled the Sea lion looked at this time. You can see in the footage that as tuna try to make a break for it and get back into the open ocean, the Sea lion would gesture towards it and it would keep swimming further and further into the trap, that would ultimately seal its fate.
What the drone also helped revealed, was that the sea lions act as a team - far more so than we originally anticipated. They appear to have different roles, with some individuals herding the tuna into the bay, some being responsible for tiring and eventually catching the tuna, and some act as 'blockers' cutting off any exits that a sneaky tuna might try and escape through.
To learn more about the behaviour and how we, like the Sea lions, worked as a team to achieve our ultimate goal watch the 'making-of' from the COASTS episode.
