Saturday 29 September
blog by Kate Yeoman, Maio Biodiversity Foundation
It’s been eventful!
We are currently in the last leg of our two week expedition in Cape Verde.
In the last few days we have been witness to the most spectacular acrobatic display by pan tropical dolphins (Stenella attenuata) where a group of 50+ we’re making the waters between Maio and Santiago boil with energy. We saw them jumping to astonishing heights and bowriding alongside our catamaran.
Later on, a tell-tale dorsal fin was spotted by Beatrice in the dusky light of the sunset, again between Santiago and Maio. Curious as to what this was we deployed the hydrophone and while all 5 observers were seeing nothing more for a fair few minutes, Beatrice’s ears were on fire with sonar, clicks and whistles! We waited in an eerie silence for a few more moments until the surface of the water erupted with a continuous sequence of pilot whale blows. Around 30 individuals surrounded the boat, swimming and diving beneath us. During the sighting, in a Noah’s Ark fashion, more individuals joined the group from the north arriving one after the other in twos. They passed within centimetres of the boat, dived underneath us and joined the group to the south. Given the time of day, behaviour and location of 2000m depth close to a steep drop off, we believe they may have been setting out on a feeding expedition.
The following day, we left Vila do Maio and journeyed to the south of the island of Santiago. The waters surrounding the capital island have previously been reported to be home to several cetacean species including beaked whales. While hopeful, our early start was soon dampened by a downpour which lasted pretty much all day! Whilst I from England am quite used to being a bit soggy, rain in Cape Verde is scarce and often treasured due to it’s huge impact on crop production.
The rain did however hinder our survey efforts quite dramatically, not only were we drenched through, our visibility was reduced to less than 100m at times. And so after a day of continued surveys through the rain we only saw a single dolphin dorsal fin until sunset when we came across a group of pilot whales once more right outside of Tarrafal, Santiago.
Due to a forecast change in wind, we journeyed through the night from Santiago to São Nicolau, full of hopes again for this well known cetacean hotspot. However, once again our luck was a little on the low side and apart from a very brief few dorsal fins in the distance of what we believe to have been pilot whales, we did not see anything by the time we anchored up in Tarrafal, São Nicolau last night.
The forecasted change in wind awoke us all with a start at 11:30pm last night where the 40 knot winds meant or anchor couldn’t hold our boat in the harbour outside of São Nicolau! Our Skipper Martin decided the best course of action was to travel a little east to find a sheltered location where the anchor could hold, but such an oasis didn’t present itself. Instead, we took it in turns to do night watches as we travelled west in the hope of finding a little more tranquility in the lee of Santa Luzia or São Vicente.
This morning poor surveying conditions continued but in spite of this Beatrice and Martin spotted what we had been longing for the entire trip – a humpback whale. However, due to winds of 25 knots and Beaufort 6, they were unable to take photos or spot the whale again. Needless to say we were all a little disheartened.
Later on in the morning, again in Beaufort 6, I spotted a beaked whale back and dorsal fin at 20m from our boat! Again however, due to the poor visibility and our inability to stop or manoeuvre efficiently in the unfortunate conditions, the animal went on it’s way without being papped!
We continued our search for calm waters until we reached a south western bay in Santa Luzia. Here we could finally stop for a late lunch and some rest without worry that our anchor would be dislodged! We continued on our way again at 18:00 with calmer waters in what appears to be a completely different sea to that which we battled against this morning.
It is now 20:00 Cape Verdean time and we are north east of São Vicente, hoping to be able to find refuge in Mindelo harbour later on tonight.
Fingers crossed for a calmer night!
Monday 24 September
blog by Kate Yeoman, Maio Biodiversity Foundation
Today we headed southeast following the coast of Maio anti-clockwise from Vila do Porto Inglês. Within our first hour of surveys we came across a group of bottlenose dolphins (Tursiops truncatus). They came to investigate our boat in their usual curious fashion and stayed with us long enough to get some photos and videos of them underwater.
Shortly after we were joined by another group, again of bottlenose dolphins. This time there were fewer of them and one with a very distinctive dorsal fin which we hadn’t seen in the previous group. We will have to study our photos later in order to determine whether we saw two separate groups or the same one twice.
Bottlenose dolphin
Whilst they have been recorded here before, bottlenose dolphins are not seen as frequently as others species of dolphin around Cape Verde so we are delighted that we were able to see them not once, but twice this morning.
Sunday 23 September
blog by Kate Yeoman, Maio Biodiversity Foundation
After arriving in Boa Vista on Friday night, we journeyed to a well-known biodiversity hotspot – the Joao Valente reef situated between the islands of Maio and Boa Vista. Whilst during the spring the northern Atlantic humpbacks are known to frequently visit this shallow area, it seems that it is not a popular spot at the moment for the southern population after no humpbacks were observed or detected on the hydrophone in this region.
Beatrice dipping hydrophone and rough-toothed dolphins
We were however visited by one of Cape Verde's more common species of cetacean the rough-toothed dolphin (Steno bredanensis). We had a small group of 5-10 individuals who first announced their presence with some energetic jumps a few hundred meters from our boat. When they arrived closer to us, they started bow-riding for a few minutes before disappearing out of sight.
We anchored up in Vila do Porto Ingles, Maio Island late last night, and while having breakfast this morning we saw two groups of dolphins. The first travelling southwest and the second feeding while travelling north-easterly about 30 minutes later. This species is most likely to be pantropical spotted dolphins (Stenella attenuata) as they have been frequently sighted in the same location during surveys by the Maio Biodiversity Foundation (FMB).
Isidoro Cardoso (Ja), one of our Cape Verdean crew members is working on the expedition to gain experience in cetacean research in order to share his knowledge with the marine team of FMB to enhance their cetacean monitoring program in the future.
Isidoro Cardoso (Ja) from Maio Biodiversity Foundation
Saturday 22 September
blog by Kate Yeoman, Maio Biodiversity Foundation
After a few technical issues with our boat we journeyed from Mindelo, São Vicente to Tarrafal São Nicolau on Tuesday 18th September. Our track took us north of São Vicente then east towards the only uninhabited island in Cape Verde – Santa Luzia. Here we saw many Red-billed tropic birds (Phaeton aethereus) which is unsurprising as there is a well known nesting sight along the cliffs to the southwest.
After 6 hours we reached the calm waters to the south of Ilheu Branco, so named due to the white sand that covers its surface. Here we stoped for lunch and we were treated to several visits from adult loggerhead turtles (Caretta caretta) who frequent the waters of Cape Verde from June to November to breed and nest. Cape Verde is in fact the third largest nesting site of this species worldwide.
After lunch, despite an abundance of birds and fish we continued onto the south of São Nicolau without any cetacean sightings, where we anchored up at Taraffal.
On Wednesday we had our first cetacean sighting of pilot whales- Globicephala sp. After traveling the entire length of São Nicolau with no sightings we turned back to find a sheltered spot for lunch. Whilst we were starting to feel concerned at the lack of cetaceans in this well known cetacean-haven around the island of Sao Nicolau, our worries soon disappeared when we encountered a group of ~30 resting pilot whales. We were able to approach the group and take photos and behavioural data without causing much disturbance.
After a little while we left them to find a calm spot for lunch and whilst we were preparing our food the same group slowly swam close to our boat with a few of the more energetic juveniles showing off with some leaps and tail slaps.
The following day we were treated again to a group of pilot whales after our long night voyage from Sao Nicolau to Boa Vista. At 6:30 am and we had a brief encounter in the first light of the morning with a smaller group of more active pilot whales. Our luck continued until later on in the morning where we encountered a small group of rough-toothed dolphins (Steno bredanensis) who showed us a few of their jumping tricks before disappearing in the opposite direction .
This morning we had a briefing on how to use the crossbow to collect biopsy samples from cetaceans. This is a vital tool in understanding the genetics and migration patterns of species such as humpback whales (Megaptera novaeangliae).
Today we travelled from Santa Monica west along the shallow ridge and then north where a group of ~100 playful pan-tropical dolphins (Stenella attenuata) crossed paths with our catamaran and had a whale of a time (pardon the pun!) bowriding and showing off all of their acrobatic skills!
We have since anchored up in the bay of Sal Rei in Boa Vista and plan to sail south to the shallows of João Valente and the island of Maio in the next day or two in the hope of finding some southern Atlantic humpback whales!
Images by Kate Yeoman
Thursday 20 September
After a difficult start in Mindelo, we left early Tuesday morning with best wind and weather conditions. While navigating to the island of São Nicolau, we crossed Santa Lucia, Branco and Raso, three small uninhabited islands. Around them we saw Loggerhead and Green turtles. Also Brown Boobies, Red Billed Tropicbirds and Cape Verde Shearwaters.
The next day we found a group of abou 40 Short-finned pilot whales near the most eastern tip of the island. We took pictures and left to have lunch in front of Cariçal, before the long crossing to Boa Vista. What a surprise to see the pilot whales appear and, through the hydrophone, listen to their whistles and their sonar clicks inspecting our boat.
We left São Nicolau and arrived at Boa Vista first light in the morning, greeted by another, but smaller, group of Short-finned pilot whales. Later we saw a jumping manta ray and a breaching Rough toothed dolphin. They were not alone: the dolphin was part of a group of 15 individuals, while the Manta was only one of the several we saw durung the whole afternoon while navigating to and from João Valente (a … very rich in life). Stravagante from bios.cv noticed tiny creatures coming up the water column, so we suppose something was spawning and the Mantas came to feed on this bounty of food.
Beatrice Jann
Skipper Martin and Ja leaving Minelo, São Vicente
Sunday 15 September
The IWDG continue their work in Cape Verde. The first expedition from Ireland to Cape Verde was in 2002 when we sailed on Joe Astons Anna M from Cape Clear to Mindelo and spent 4 weeks trying to locate and photograph humpback whales. We were successful, contributing 11 more fluke shots to a catalogue of only 60 individuals.
We returned in 2006 for a month but this time chartered a 45ft Benetton yacht in Cape Verde. Again we obtained more fluke shots from humpback whales and recorded a large variety of other interesting species. In Spring 2011 and 2012, Conor Ryan and Darren Craig of the IWDG spent 6 weeks in BoaVista doing day trips out on a small RIB to collect biopsy samples; the data was used towards Conor's PhD from the Galway-Mayo Institute ot Technology.
In 2014 and 2015 we returned in the autumn chartering a 41 ft Lipari catamaran, a time when humpbacks from the northern hemisphere should be on their feeding grounds (like Ireland) but sightings had been reported. We were successful in obtaining sightings, fluke shots and biopsy samples to show these were indeed southern hemisphere humpback whales crossing the equator to Cape Verde. This year we continue with this work but a main objective is to train up local Cape Verde researchers and students in whale and dolphin survey techniques.
Our colleague Beatrice Jann from the Swiss Whale Society is leading the expedition on the same 41ft Lipari catamaran we chartered in 2014 and 2015. Onboard with Beatrice will be skipper Martin, Kate and Ja from the Maio Biodiversity Foundation http://fmb-maio.org and Stravagante and Katia from Bios.CV http://www.bioscaboverde.com. They will spend the next two weeks sailing the waters from São Vicente to São Nicolau and BoaVista to Maio in search of humpback whales, but will of course record all sightings, cetaceans, turtles, sharks, and rays.
Cape Verde is one of the most important sites in the North Atlantic for humpback whales and now it is the only site where populations from two hemispheres use as a breding ground but at different times of year.
Follow this years expedition on https://www.facebook.com/CVI-Expedition-2014-2015-491580284277939/
Cape Verde 2018 is sponsored by the:
