Helen Swift and Tom Forster; Research Surveyors for MARINElife (Registered Charity No. 1110884; Registered Company No. 5057367)
Outbound:Sea state 5 initially, falling gradually to 1 inshore near Calais, excellent visibility (>20 km), some slight starboard glare during first half of crossing
Return:Sea state 1 near Calais rising to 5 from the mid-channel onwards, excellent visibility (>20 km), some slight port-ahead glare.
Summary of sightings:
Harbour porpoise Phocoena phocoena 10
Black-headed Gull Chroicocephalus ridibundus 120
Common Gull Larus canus 4
Cormorant Phalacrocorax carbo 2
Fulmar Fulmarus glacialis 1
Gannet Morus bassanus 330
Great Black-backed Gull Larus marinus 34
Herring Gull Larus argentatus 17
Kittiwake Rissa tridactyla 41
Lesser Black-backed Gull Larus fuscus 9
Little Gull Hydrocoloeus minutus 5
Razorbill Alca torda 2
Unidentified Gull sp. 25
Unidentified Larus Gull sp. 22
Unidentified Auk sp. 4
Starling Sturnus vulgaris 26
Our survey got off to a good start as Helen spotted a Peregrine passing over us as we drove towards passport control at the Dover terminal. The cliffs have always looked promising here for Peregrine, but this is the first time we have seen one here. Sadly, I could not see it as my eyes were on driving but once parked in the waiting area for loading, we scanned the cliffs in the hope of catching further sight of it. We had no further sign and had to satisfy ourselves with a Kestrel hovering over the cliff top but will be keeping our eyes out in future in the port.
Departing Dover, conditions were a stark contrast to our Dunkirk survey a couple of weeks ago; instead of the flat calm of that survey we were greeted by a stiff north wind and consequent sea-state 5 with a moderate swell and some starboard glare. All in all, it looked like it might be lively for seabirds but it seemed unlikely we would see any cetaceans on this survey. As we departed the port we were immediately greeted by a variety of gulls - Herring, Great Black-backed and Lesser Black-backed, soon followed by our first Kittiwake. A surprise sighting was a flock of 25 Starling headed north-west towards Dover, we presume heading over to winter in the UK from France. A minute later we saw a further starling low to the water and heading west, we wondered if this had become detached from the main flock and hope it managed to re-orientate itself and make landfall.
About 20 minutes into the survey, Gannet numbers started to rapidly rise suggesting there might be fish in the area. Eleven Gannet were sitting together on the water looking like they had recently fed but none were diving. As we approached the area, Helen spotted dorsal fins rapidly breaking the surface as 3 cetaceans swam away from the Gannets. At first glance she thought dolphins due to the numbers together, rapid swimming and splashy simultaneous surfacing, but on closer inspection as they repeatedly surfaced, we realised these were the usual Harbour Porpoise so often seen on this route. Normally discrete and sedate, these were lively and active in a way we have never seen before, swimming much more purposefully and less 'porpoisefully' than usual - we suspect chasing fish.
Frequent Gannet continued and soon we had our second porpoise sighting, spotting two more surfacing ahead of us. Again, these were quite lively and instead of the usual tantalisingly brief glimpse we have so often had, these treated us to prolonged views as they passed by and into the wake, surfacing several times through the waves of the wake itself. It was not exactly dolphin-style playing in the wake, but as near as we ever expect to see in a porpoise. One was noticeably smaller than the other and we think they were a mother and juvenile.
As we neared the French coast the waters calmed markedly and by the time we reached Calais the sea-state had calmed right down to sea-state 1 in very marked contrast to Dover. Another ferry was departing as we came in and a large flock of Black-headed Gull followed it out looking for items stirred up in its wake.
After the usual efficient turnaround in Calais we departed in conditions that exactly mirrored our outward crossing; calm near Calais becoming rapidly livelier as we departed the shelter of the French Coast. The big difference was the Gannet. Whilst outbound we had seen a fair number, on leaving Calais there were many, many more - it is always remarkable how swiftly they can gather and numbers change in one area in such a small space of time. Many of the Gannet were circling high, clearly actively searching for fish and it was not long before we spotted the first of several feeding frenzies, this one sadly too far distant to see if there were any cetaceans with it. So much was happening and so widely that it was difficult to keep pace, we did manage though and were rewarded for our care by spotting 5 Little Gull serenely passing through the milling Gannet. Gannet activity continued to build and soon we had a very large feeding frenzy with about seventy diving in a flock that moved progressively across the path of the ferry. It looked like there had to be cetaceans with them to keep the fish near the surface and soon I spotted three Harbour Porpoise very actively swimming and feeding near the leading edge of the Gannet activity though views were brief.
Further Gannet feeding continued in groups widely scattered over a huge area and our fourth porpoise sighting soon followed with a lone porpoise seen with a group of 11 diving Gannet. This whole period of activity was by far the most active we have ever seen in the Straits of Dover. Given the numbers of Gannet and activity over such a wide area we wonder just how many more porpoise there might have been, especially given that we were spotting them amid the waves of a sea-state 4 rising to 5. The remainder of our crossing back to Dover was lively with gulls including many Kittiwake scudding along amidst the rising winds but by contrast it seemed quite quiet. This was quite a memorable survey for us and as often on this route it is amazing how much there is to see in such a short crossing. Definitely a reminder to us not to be put off by the weather or sea-conditions - you never know what may still be out there.
Our thanks to Captain Maçon and the crew of Côte de Flandres for making us welcome and looking after us throughout the survey.
Harbour Porpoise (Peter Howlett)
Gannet (Rob Petley-Jones)