Spinner Dolphins East of Kisite-Mpunguti Marine Protected Area
I take the tiller, captaining the boat east out of the Wasini channel, the rest of the team assume positions for dedicated watch. Passing the coastal forest of Shimoni I spot a colobus in the canopy and an African Fish Eagle... but today is the marine research programme, and it's dolphins and turtles that we search for.
Rounding the south-east corner of Shimoni peninsula we enter Funzi bay, hoping to spot Indo-Pacific humpback dolphins that favour these near-shore habitats. No sign of them today. We pass a green turtle, but sadly a recently dead one floating at the water's surface. No obvious cause of death, but this time of the year, during the kaskazi winds (the NE monsoon winds), seems to bring a peak of turtle mortalities each year.
Much of Funzi bay is shallow and doesn't leave us much room to manoeuvre so we turn the boat around and head south, towards the continental shelf and open water. A flock of terns dives persistently at the water's surface but the fish shoal they target has gone unnoticed by any dolphin.
A more distant splash and a suspected dolphin sighting, something dark and rounded surfacing. Half-way there before it becomes evident it's another dead turtle bobbing at the surface. A huge one this time, a hawksbill, it's been dead for longer and given the size it reached, somehow a sadder loss as we circle around it and continue our route south.
Sergi, our marine research officer takes over from me at the stern as I join the rotation of observers up front, each with our 45 degree field of view to patrol. Tom calls out a potential dolphin far ahead, an apparent leap and splash, Sergi steers us toward the point on the horizon and we keep scanning the surface. We rotate positions, both Tom and I looking forward, he sees something again, but is disappointed when there's no following dorsal fins or repeat splashes.
Still we head further south, further from the shore and are rewarded 15 minutes later by 4 dorsal fins breaking the water's surface ahead. They approach the boat to ride the bow and a further 3 dorsal fins join them. We expect them to be Indian Ocean bottlenose dolphins out here, but the small triangular fins, the smaller torpedo-like bodies and the long narrow beaks all point to something different. Three tone body colouration as they surface confirms we have found a small group of spinner dolphins.
Sergi hands me the camera, I try to get photos of the dorsal fins of each one as they surface to breathe. It's not as easy as it seems it should be. Unpredictable quite where and when they will surface as they dart across the bow just below the surface, the angle has to be right, the sun behind, sharp focus... and you have to be quick. Sergi uses the time to talk the team of observers through the dolphins' behaviour. Close to the surface, regular slow shallow surfacing, no obvious directional travel; they were probably resting.
We leave the small group and within minutes a lone individual further away leaps from the water, an acrobatic spin that gives them their name. Then 10 dorsal fins surface to our right. We barely get through counting them when at least 20 fins appear on the right. Our group of 7 was actually part of a larger group, in the end we estimate 40 to 50 individuals.
Spinner dolphins are thought to be seasonal visitors to this part of the Kenyan coast, possibly crossing the channel from Pemba, following the food with the kaskazi. In previous years we have recorded them between mid-February to mid-March, in large active groups (up to and over 200) off the shelf, south of the MPA. This kaskazi we had one sighting in December, and then last week. We do not think that this season represents any 'break from the routine' but more likely that our new research vessel gives us a higher, clearer viewing platform, and survey routes take us further from shore so we simply see more. The real excitement is that we are now understanding more about these seasonal visitors; their 'season' is longer than we first thought, and they are using habitats east of the MPA for resting suggesting they may be here for more than just quick foraging forays. Ironically, the fact that they are consistently recorded outside of the marine protected area is not of too great concern. They are free from disturbance by the dolphin-watching tourist boats and in the absence of commercial fishing activities are not threatened here by high levels of accidental deaths from by-catch that plague some of their open-ocean counter-parts through industries such as tuna fisheries which are a further from being as 'dolphin-friendly' as they would like to claim.
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