The Humpback of Certainty ?

6th Apr 2003 As if flicked open the front page of my new book which my wife, Frances, had bought me for the journey to Cape Verde, under "The Salmon of Doubt" by Douglas Adams, she had written "The Humpback of Certainty". A lovely thought but was I so confident ?

Successive groups of researchers had visited the Cape Verde archipelago searching for humpback whales in an attempt to answer the last mystery of humpback whale migration in the North Atlantic, where are the feeding grounds of these whales and where do they go when they leave the Cape Verde ? To answer these questions they have tried to locate humpback whales and photograph their tail flukes in order to compare with similar images taken all around the Atlantic Ocean in an attempt to find a match.

Since 1999, only 26 whales had been photographed, which made me wonder how successful would we be, given that we had no idea what it would be like working around these islands (now up to 42 following analysis of 2002 data). I admitted to Tony that I felt under pressure, under pressure to ensure that we justified the funding we had obtained and, more importantly, that having travelled so far from Ireland that we achieved something and contributed to the knowledge of whales and dolphins in this area.

As we sailed south from Sao de Sal we rotated watches to try and ensure we had somebody continually watching for signs of whales. Due to the batteries on the 'Anna M' being quite low, we sampled the hydrophone at regular intervals, rather than listening continuously, hoping we might pick up vocalisations of whales or dolphins. As time went by, you wonder what are you actually looking for and would you recognise the cues when they occurred. Sea state was good for observing cetaceans (1-2) but we had no idea how difficult it would be. Are they spread out over a large area ? Distributed in discrete sites which we have to find ? Maybe this year fewer will return to the breeding grounds, making them more difficult to locate.

All these negative thoughts were blown away when Ian shouted "Two blows over there". We scrambled to look at where he was pointing and there was the bushy blows of two humpback whales. Over the next hour we managed to get 35 minutes of recordings of humpback whale song as well as some fluke images, although all from a distance.

The following day we saw humpbacks breaching in the distance only 14 minutes after weighing anchor at Sal Rei on Boavista. We got at least four good fluke shots, 5 recordings of singing whales and at least 3 close encounters for Tony to film. We were even visited briefly, on two occasions, by a small group of Rough-toothed dolphins, that seemed to check out our towed hydrophone.

I never thought it would be this easy.

After a day ashore to take on provisions and investigate reports of a dolphin graveyard on the far eastern side of the island, we spent another day on April 1 photographing and filming whales. Surprisingly, that although there were plenty of whales around we heard no singing all day. I have no idea why that should be, maybe the males (they are the ones that sing) needed a rest. As the day went on, wind speed increased until it was up to Beaufort 6-7 and sea-state 4-5. Not ideal conditions for observing whales though they seemed not too mind as two breached over and over again for over 30 minutes as we inched our way closer to them, tacking over and over again to try and get closer enough to film.

We had already decided to sail overnight to Sao Nicolau and Sao Vincente where we had to contact the authorities for permission to work in Cape Verde waters. This seemed like a good time to leave behind the whales for a few days in the hope that we would find them again on our return.

Our plan over the next week is to survey waters around Sao Nicolau and Sao Vincente, areas which were once rich whaling grounds but have had few humpback whale sightings in recent years.

I was relieved that w