Looking for Cetaceans on the North West Herring Survey

6th Jul 2015

Greetings from the North Atlantic! Michael Marrinan and Marissa Parker here, marine mammal observers on board the RV Celtic Explorer as she carries out an acoustic survey of the Northwest herring stock. Our role on board is to spend three weeks observing and recording any megafauna that we may encounter on behalf of the Irish Whale and Dolphin Group as part of their ongoing offshore surveys to record the distribution and abundance of whales, dolphins and porpoise in the Irish EEZ. Our observation platform, for the duration of this voyage, is the crow's nest (can you see the comfortable looking place with the windows above the bridge in the picture of the "Explorer" below? Yep! Well outside that!), our home for the 21 days.

R.V. "Celtic Explorer" in Galway docks, note the crow's nest, brrrrrrrrr!

Joining the crew and the other fisheries scientists (Cormac, Mike, Andrew and Brendan acoustic observers, Marcin, Toby, Turloch, Dylan and Dylan, Biologists) our journey began on the 24 June with an overnight steam from Galway to beautiful Killary Harbour. Arriving at 07:00 on Thursday 25 June, the crew and the acoustic observers set about calibrating their gear while we set about ensuring (for the 100th time) that our equipment was working. With calibration taking the next 8hrs, in which time the boat slowly turns in a circle in the same spot, it was with great relief that we set off from Killary and began our survey in earnest. Leaving Killary we headed north along the coast of Mayo, Sligo, Donegal and up into the North Atlantic. Unfortunately poor weather conditions yielded no sightings for our first day of observations, but it gave us a chance to get our eye in and adjust to being at sea.

Killary Harbour looking ominous

Day 2 (Friday 26 June) brought with it better weather and the chance to get our first sighting of this journey. We were duly obliged within an hour of commencing our survey when, at 07:49, we spotted a small pod of common dolphins (Delphinus delphis) on our port side, as we headed from the North coast of Ireland to the Outer Hebrides. You can always depend on these aptly named and photogenic little guys to show up and put on a show as they bowride and leap out of the water. This was the first of many encounters we were to have with this species over the next week!

Common dolphins spotted almost everywhere!!!!

Soon after our common dolphins, we encountered our first medium sized cetacean. At around 09:00, Marissa noticed two animals surfacing around 50m from the boat. The animals surfaced again around 100m from the boat and both Marissa and Michael saw one large animal around 17ft long which was accompanied by a much smaller animal of around 9ft. They were both brown/green in colour with the dorsal fin placed quite a ways down the back, however due to the erratic way that they were surfacing (they were surfacing in a zigzag!) a definite identification could not be made and no pictures were taken unfortunately. As we began our northward journey between South Uist, The Small Isles and The Isle of Skye we encountered another couple of pods of common dolphins and things seemed to be petering out when all of a sudden of the bow of the boat at about 200m a large animal breached completely out of the water. A little bit shocked at what had just occurred, we were ill prepared for the second breach a couple of seconds later. The animal in question was in the region of 7 to 8m long and extremely bulky. A light brown in colour it had a large bulbous melon with a dolphin like beak, not only that but there were two of them, the second which did not breach was slightly smaller. Once again as soon as they came they disappeared, but with three people witnessing the second breach and with the animal completely out of the water we identified it as a Northern Bottlenose Whale! It was amazing to see these wonderful animals in such a beautiful setting. Two round off our second day of observations, we were surrounded by several groups of common dolphins which when all told, numbered maybe 25 to 30 individuals. Very nice! Day three (Saturday 27 June) took us into The North Minch, the weather once again was fine with good visibility and very little wind. After the excitement of the previous day, hopes were high for a good day of observations in this cetacean hotspot and we were not disappointed. The straight of water between the Isle of Lewis and the Scottish mainland provided two sightings of our old pal the common dolphin within the hour and by 11:00 we had 5 sightings of this apparently widely abundant species. At 12:03, after spotting a gannet that had what appeared to be fishing line attached to its foot and following it to a group of diving gannets about 1200m of our starboard side, we spotted another pod of common dolphins intent on feeding on what we presumed to be a bait ball of fish. We observed this feeding behaviour for a couple of minutes when all of a sudden the gannets took flight and the dolphins seemed to bolt. Seconds later there was a large lunge in the water and a medium sized whale swam through where the dolphins and gannets had been feeding. This animal appeared to be three or four times the size of the dolphins and there were flashes of white with a long torpedo shape, we put this one down as probably or first minke whale.

Some marine litter on this poor gannet

A minke passed this way and all we got was this lousy picture

At 12:55 Marissa noticed a breach about 500m from the port side of the boat, ever the quick thinker she picked up the camera and snapped the fins of two bottle nosed dolphins (see pics below). But who are these dolphins, we know that there is a resident pod in the Moray Firth not too far away, could these be members of this group?

Two bottlenose dolphins spotted in the north of The Minch

There were three more sightings of common dolphins, the last being just before 7, these were to be the last sightings until Monday as bad weather with high winds and a big swell prevented any surveying being done on Sunday (28 June). Just as we were reaching the most northern part of the survey, we were thwarted. This would not be the last time that the weather put a halt to our surveying! With Sunday being a blow out, although we did try on several occasions to get something going, we looked forward to better weather and more sightings for Mondays (29 June) survey. Heading west of the Orkneys and out towards the continental shelf the weather was fairly reasonable, however sightings were few and far between with just the three groups of common dolphins coming to visit. Always happy to see the common dolphins, when sightings are scarce these guys always bring a smile and keep the spirits up, it was a bit of a come down from the excitement of the previous Friday and Saturday. On the way back from the shelf edge on Tuesday (30 June) we had a bit more luck as we cruised past the north coast of Scotland twice, once heading east towards the Orkneys and then turning west heading back towards the continental shelf. The weather was extremely good and the water in the shade of Scotland appeared at times like a mirror, perfect for spotting cetaceans, and that we did along with some very dramatic scenery!

The north coast of Scotland, very dramatic and very beautiful

Our first sighting was brought to our attention by a crew member from Cork by the name of Noel at 11:10. He was on watch as a large unidentified cetacean breached of the port side of the boat as we headed east. A medium sized whale was the verdict; however the observers only saw the great big splash. Will or luck ever bring us the chance to photograph one of these guys? That sighting was followed by the now obligatory appearance of the common dolphin, but then at around 16:10, just before we headed south towards the beautiful Scottish coast and its beautiful vistas with the Highlands as the setting, Marissa spotted a minke whale surfacing about 200m from the boat. At last the chance to get a picture of one of the baleen whales. Happy days! The minke was followed at 19:15 by three bottlenose dolphins for only their second appearance this survey. At 19:45 another surprise when the second largest fish in the world put in two appearances. Two separate sightings of individual basking sharks behaving just like basking sharks should with their slow lazy swim on the surface of the water. Perfect to round off very successful days observations and too end our first week on the RV Celtic Explorer.

Minke whale of the north coast of Scotland