Steve Morgan - Research Surveyor for MARINElife
Conditions westbound: Sea state 1-2; wind NW very light; visibility moderate
Conditions eastbound: Sea state 2-4; wind SE-SW moderate; visibility poor with fog/mist
Summary of sightings
Cetaceans and mammals:
Bottlenose Dolphin Tursiops truncatus 1
Harbour Porpoise Phocoena phocoena 44
Grey Seal Halichoerus grypus 8
Unidentified Seal Species 2
Atlantic Fulmar Fulmarus glacialis 4
Manx Shearwater Puffinus puffinus 25
Storm Petrel Hydrobates pelagicus 1
Gannet Morus bassanus 19
Common Scoter Melanitta nigra 25
Great Cormorant Phalacorcorax carbo 111
Shag Phalacrocorax aristotelis 22
Black-headed Gull Croicephalus ridibundus 26
Common Gull Larus Canus 15
Herring Gull Larus argentatus 215
Lesser Black-backed Gull Larus fuscus 11
Great Black-backed Gull Larus marinus 2
Kittiwake Rissa tridactyla 58
Sandwich Tern Sterna sandvicensis 1
Guillemot Uria aalge 397
Razorbill Alca torda 127
Auk sp. 601
Gull sp. 242
Diver Sp 3
Terrestrial birds during survey effort
Rock Pipit Anthus petrosus 1
Barn Swallow Hirundo rustica 4
Oystercatcher Haematopus ostreolagus 2
Unidentified Passerines (at sea) 6
I arrived at Brocklebank Dock in Liverpool to find bright sunshine and still conditions and in the dock the water's surface looked like glass, so the prospects for the day ahead looked excellent! I was quickly checked in by Seatruck's efficient staff and escorted onto the "Seatruck Power", my ship for the outbound passage to Dublin.
After clearing the sea lock we turned and sailed out into the Mersey estuary where large numbers of gulls were present, mostly Herring Gull and with a high proportion of juveniles. As ever, substantial numbers of Cormorant were standing on the sands at Crosby along with large flocks of gulls too distant to be identified. We weren't even clear of the Mersey before the first Grey Seal of the day rolled in front of our bows.
Beyond the wind farm, about an hour out to sea, I began encountering Harbour Porpoise. This area along the North Wales coast seems to produce porpoise regularly and this was no exception with sightings coming one after another. In the almost perfect conditions with a sea state of 2 dropping later to 1, spotting porpoise was easy and by early afternoon I was already in double figures!
Sightings of Porpoise continued regularly throughout the crossing and by the time we arrived in Dublin Bay I had accounted for an unusually large total of 39. As the day wore on the sea got flatter and flatter and I was able to spot the tiny dorsal fins of surfacing porpoise at quite long range. Ordinarily, even in quite a gentle sea, this would have been impossible.
We pulled into Dublin Bay in the early evening and Captain Kieron Daley came up to the bridge to supervise our imminent berthing. As I chatted to him he suddenly announced "oh, there's a Dolphin or something". I suspected that it might be another porpoise but his identification was instantly confirmed as a single Bottlenose Dolphin leaped clear of the water barely 50 metres in front of our bows. That proved to be the final marine mammal of the crossing as, somewhat surprisingly, there were no Common Seal loitering around the Liffey estuary.
The return crossing the next morning saw the end of such wonderful conditions. The sunshine soon gave way to cloud and then to fog and I had to abandon the survey for nearly an hour at one point as visibility dropped to less than 100 metres. The fog eventually lifted to the extent that I could resume work but visibility was still very poor. Moreover, a rather brisk south-westerly breeze had blown up and the mill-pond conditions of the previous day had by then given way to a choppy sea, so this was going to be much more challenging!
I did find a few Harbour Porpoise, including three very close to the Mersey estuary, but the sightings were brief and cryptic - just glimpses of stubby dorsal fins breaking the waves.
Both legs produced vast numbers of Guillemot and Razorbill and equally large numbers of auks that could have been either species. It had been some time since I had seen so many in the Irish Sea. There were also some early Manx Shearwater, all of these encountered on the return leg, with a tiny Storm Petrel buzzing across the choppy surface of the water.
Several Barn Swallow passed us by en-route to Wales and a very confused Rock Pipit came to visit us, perching on the safety rail in front of the bridge. Gannet, divers and Fulmar were a little sparse but gull numbers were good. It was nice to see a Sandwich Tern too.
It had been a very enjoyable and productive survey and one which illustrated just how different each day at sea could be. Notwithstanding the deterioration in observing conditions, on the first day it was remarkable how the sea seemed to be full of Harbour Porpoise and seals, yet twenty-four hours later exactly the same waters seemed virtually barren.
As usual at Seatruck the staff and crews were fantastically helpful and welcoming and a special "thank you" to the seaman on the Progress who brought round slabs of fruit cake to everyone on the bridge! I look forward to returning to this fascinating and sometimes enigmatic route soon.
Steve Morgan - Research Surveyor for MARINElife