BWAS 2017: Rockall Trough Part Two - Cetaceans

Blue Whiting Acoustic Survey 2017 Week Two: Saturday 25^th to Friday 31^st March
by Sean O'Callaghan (IWDG Marine Mammal Observer)

The second week of BWAS marine mammal surveys got off to a blank start initially but the following day (Sunday) really signaled the start of a far more productive period.

Survey progress map for 31st March 2017 with thick lines show areas covered (c) Marine Institute

Not long after ascending into the crow’s nest to start the day's effort and while getting myself ready (equipping the necessary gear for the day along with applying some sun cream!) the seabird team began their observations from the bridge deck and spotted the first whales of the day which appeared initially 500m off the starboard bow, lazily surfacing, all the while moving closer to RV Celtic Explorer. Their slanted blows and boxed body shape gave them away as sperm whales and the three of them (one obviously large individual with two smaller individuals, probably juveniles) came within 100m of the vessel before diving under the bow. Moby Dick's relations up-close and personal, a great start to the day! 

Sperm whales (c) Niall T. Keogh

Sperm whales (c) Sean O'Callaghan

Sperm whale dive sequence (c) Sean O'Callaghan

An hour later, two tall blows were picked up out towards the horizon some 2.5km off the bow and when we reached the area both whales passed the vessel, decent views giving them away as fin whales on the move. The most elusive of the Sunday sightings was of an unidentified beaked whale picked up once by Aude through her binoculars while I was on a break. To round the day off we had a few common dolphins make an appearance off the port side showing no interest in the ship which has been the case for most of the survey. We had caught up with the fishing fleet on the northern side of the Porcupine Bank that day and had views of some of the large factory trawlers.

Maartje Theadora (c) Niall T. Keogh

The next batch of activity happened two days later along the shelf edge some 60km west off Mayo where more common dolphins were sighted in the morning while a group of long-finned pilot whales were recorded visually and acoustically simultaneously a kilometre and a half of the port side in the evening (really displaying how both survey methods can complement one another). While trying to get record shots of these pilot whales a distant blow from a large whale was inadvertently captured in their midst’s just as a group of offshore bottlenose dolphins powered past the starboard side to be picked up by those on watch in the bridge along with the seabird team who were up from dinner to see the pilot whales. Unfortunately these dolphins didn’t hang around and continued off in synchronised breaches which were the best that could be captured by the camera. Another day another species for the list!

Offshore bottlenose dolphins (c) Sean O'Callaghan

Wednesday was a day for housekeeping with heavy rain in the morning coupled with poor sea conditions which were unsuitable to watch or safely work in. Thursday was an unexpectedly interesting day, we had moved north into Scottish waters off the Hebrides with a species list standing at six but there was more transects to go yet. The weather had eased off and we were back on effort again. After turning onto a new transect at around 15:00, Aude started to hear a strange sounding whistle on the hydrophone, seemingly getting closer as time passed by. Continuing to watch from the crow's nest with the possibility of a new species in the area it didn’t take long to spot a large, grey, odd-shaped ship lingering on the horizon. We had heard that the survey tracklines might take us past a military exercise later in the day involving submarines, so with the navy-style appearance of the distant ship coupled with the consistency of the whistles being detected on the hydrophone, it became obvious that sonar was being used. About 30 minutes after the first ship was seen, another four appeared on the horizon to the east around the same time as the first marine mammal sighting of the day was made; a group of ten or so common dolphins moving west ahead of us at high speed! The sonar was detected for a further three hours, during which time another lone common was sighted but seemed unphased by the sound (in contrast to the previous sighting). Further sightings of common dolphins, two unidentified large whales and our first Minke whale of the survey capped off the day nicely as we continued north along the shelf edge and over shallow waters. 

Common dolphin (c) Niall T. Keogh

Navy vessels taking part in the 'Operation Joint Warrior' exercise (c) Sean O'Callaghan

Friday proved to be a fruitful day while over the deep Rockall Trough waters near the Anton Dohrn Seamount, with twenty long-finned pilot whales less than 200m off the port side just after conducting a fishing tow and before the day's watch effort began. This group of pilots engaged in some interesting behaviour such as 'spy-hopping'. Later on a lone Atlantic white-sided dolphin was seen to surface twice, giving tantalisingly brief views of the colourful side pattern but just not enough to put it down as a "definite" sighting for that species.

The day ended as the drizzle closed in from the east, with a lone large blow picked up from the crow’s nest some 3km away. Subsequent rain knocked the survey off effort for a while but as soon as it cleared we were met with the sight of a single fin whale lunging in front of the bow almost on cue in perfect sea conditions! It lunged a further three times as we steamed by, making for a nice end to the week despite heavier rain closing in!

Long-finned pilot whales 'logging' at the surface (c) Sean O'Callaghan

Long-finned pilot whale 'spy-hopping'! (c) Sean O'Callaghan

Lunge-feeding fin whale (c) Sean O'Callaghan

Fin whale lunge-feeding sequence (c) Sean O'Callaghan

Our man in the crow's nest... Sean wonders what species is next up for the marine mammal team! (c) Niall T. Keogh

BWAS 2017: Porcupine Bank

Blue Whiting Acoustic Survey 2017 Week One: Saturday 18th to Friday 24th March

The survey team for BWAS 2017 met on RV Celtic Explorer in Galway Docks the day after St. Patrick's Day, heading out into Galway Bay that evening. The next day was mostly spent just off Black Head where the fisheries team from the Marine Institute made use of the calm bay waters to calibrate their acoustic survey equipment. The seabird team took this opportunity to go through survey techniques and identification training, with eleven species seen including Great Northern Diver, Black Guillemot and Common Gull (inshore species which we are unlikely to see while offshore). No sign of any marine mammals there however. We set sail that evening and made our way towards the start of the transect lines over the southern end of the Porcupine Bank.

The mix of habitats around the Porcupine Bank include the relative shallows over the bank itself, bordered by continental shelf edge slope and deep abyssal waters beyond, making the region one of the most diverse areas for marine life in the Irish offshore territory. Unfortunately for us, Monday right through to Thursday afternoon was spent battling into the teeth of a northerly gale in this area! As such, the potential for sightings was limited.

We surveyed from inside the ship's bridge during this time, which made staring out at the (gusting) Storm Force 10 winds, hail and 6m swell somewhat bearable but reduced our chances of seeing much. Just one sighting of marine mammals occurred during these first few days, a group of seven Common Dolphins (including a calf) which came straight in to our bow in rough seas. PAM was more active however with plenty of dolphin whistles and Pilot Whale vocalisations picked up by the hydrophone.

A howling sea over the Porcupine Bank (c) Niall T. Keogh

Hail building up on the deck! (c) Niall T. Keogh

A break in the weather finally came through on Thursday afternoon, when the low pressure made its way south and we cleared through it to calmer seas over the shallow waters of the bank. Our determination during the previous few days was rewarded that evening by a couple of sightings of a distant large baleen whale. Views were had of the blow only but more than likely this was a fin whale. 

Sunset (c) Sean O'Callaghan

Friday saw us surveying over deep waters (1500m or so) to the north west of the bank with calm seas and bright, clear conditions on our side. Within the first 15 minutes of the morning watch, our MMO in the crow's nest spotted two Sperm Whale blows about 2km dead ahead of the ship! We had a few more sightings of them as they made their way past us, heading south at about 1km range a little later. Not long after, the seabird team picked up a group of five or so Long-finned Pilot Whales coming in to investigate the ship but they cleared off soon after, just a few record pics taken to document their occurrence. It was great to finally see these two expected (but welcome!), deep water species.

A further sighting of a whale blow (likely another Sperm Whale), a single Common dolphin and detections of dolphin whistles and sperm whale clicks on PAM rounded off the first good day of survey for us.

Long-finned Pilot Whale / Calderón Común /  Globicéphale Commun (c) Niall T. Keogh

Dolphin whistles on PAM

Aude listening for cetacean vocalisations on PAM

The seabird team had plenty to look at during the rough weather but this mostly involved birds which were following the ship, riding along in the updrafts and presumably hoping we would stop to go fishing at some stage. Gannets, Kittiwakes, Fulmars, Great Black-backed Gulls and Lesser Black-backed Gulls made up the bulk of seabirds in attendance while a scattering of Great Skuas, Sooty Shearwaters and a single Glaucous Gull added interest as did some Manx Shearwaters doing their own thing, heading past us further out at sea. Once the calm weather took hold, we were able to see a few Puffins here and there in between the waves and swell. 

Gannet / Alcatraz / Fou de Bassan

Nearly all the Gannets we see out here are pristine white adult birds or near-adults. It was nice therefore to see this younger bird (a 2nd calendar-year) which certainly stood out from the crowd! (c) Niall T. Keogh

Great Skua / Págalo Grande / Grand Labbe (c) Niall T. Keogh

3rd calendar-year Glaucous Gull / Gaviota Hiperbórea / Goéland Bourgmestre (c) Niall T. Keogh

WESPAS Days 7 to 9: Porcupine Bank Part Two

Days 7 to 9 sightings: 10th, 11th and 12th July 2016

A low pressure system swept up from the southwest and across our tracklines over the Porcupine Bank through Saturday evening and the first half of Sunday, making conditions unsuitable for on deck surveys. We still powered on by watching from inside the bridge of RV Celtic Explorer until a break in the weather and reduction in swell height allowed us back out once more on Sunday evening. 

Choppy seas with cresting waves and large white caps are not ideal for detecting cetaceans but true to form, a couple of groups of long-finned pilot whales came in close to the ship for a look-see, meaning our efforts didn't draw a blank. Pilot whales are often the only species you can count on seeing on such rough days.

Long-finned pilot whale (c) Niall T. Keogh

Long-finned pilot whales (c) Niall T. Keogh

Through Sunday evening and Monday, we steamed over the steeper western slopes of the Porcupine Bank in order to retrieve three Static Acoustic Monitoring (SAM) devices deployed here in March to record cetacean vocalisations (more on this in an upcoming blog post). The route between each of the SAM sites brought us over some great habitat which didn't disappoint.

Conditions were much improved at this stage and allowed us to spot the blow of a large baleen whale dead ahead at about 3km range. As we got closer and closer it became clear that it was a fin whale, the second largest animal on earth (only blue whale is larger). Fin whale is the most abundant large whale in Irish waters so we were expecting to record this species soon enough but still always a pleasure seeing them!

Fin whale (c) John Power

On Monday evening we were treated to an amazing flurry of activity as we headed up and over the shelf edge from deep to shallow waters. While over the 600m contour line we started picking up several small groups of pilot whales and common dolphins in loose association making their way past the ship. It soon became apparent that these were part of an overall widespread aggregation which was topped off by a sighting of 10 or so striped dolphins in full corkscrew-style breaching mode! 

Striped dolphins are typically associated with warmer sub-tropical waters, being common in the Bay of Biscay and Mediterranean Sea but less frequently recorded in Irish waters and usually in the deeper parts of the southwest section of our offshore territory in the summer/autumn. That being said, members of the current survey team were out here in March during the Blue Whiting Acoustic Survey on RV Celtic Explorer and recorded striped dolphins in much the same area. Perhaps there is more to learn about their occurrence here yet.

Striped dolphin (c) John Power

Striped dolphins (c) John Power

The highlight of the past couple of days relates to two sightings of animals from the poorly understood group known as beaked whales. These cetaceans live in deep offshore waters where they favour underwater canyons and seamounts as foraging grounds, searching for squid. They are deep diving specialists, small, sleek and not often observed at the surface, especially from large ships. Identification of beaked whales at sea is fraught with uncertainty and good photographs of the head are often required to check for the diagnostic positioning of erupting teeth along the lower jaw on males in particular. 

We had good views of a group of three animals surfacing on multiple occasions alongside the ship at 250m range on Sunday evening, well enough to see the heads of the two adult type animals (the third was a smaller juvenile). The views of the head shape and overall colouration of the animals would suggest that Sowerby's beaked whale was the species in question. These are thought to be the most abundant Mesoplodon beaked whales in Irish waters but there is still a lot to learn here.

We were inside the bridge when we spotted the group of three beaked whales so between the ensuing excitement (...panic!) and the fact that we were looking through glass windows, the only pics we managed to get were very much of a 'for the record' quality but we are still chuffed with the sighting!

On Monday afternoon we encountered a Mesoplodon type beaked whale which breached fully out of the water four times in a row, albeit at a distance of about 700m. No matter how many times you get to see beaked whales (if you're that lucky), they always leave you wanting more! 

Beaked whale (presumed Sowerby's) (c) John Power

Monday ended with a respectable total of 18 sightings of cetaceans logged for the day.

We said goodbye to the Porcupine Bank this morning but not before we encountered yet more long-finned pilot whales and a small group of offshore bottlenose dolphins (a new species for the survey list).

Now making our way towards the next set of transect lines closer inshore off the west coast, common dolphins following us as we go.

Common dolphin (c) Mick Marrinan

The seabird team have had a less hectic time of it with low numbers of birds present along the western side of the Porcupine Bank, which has been a bit of a surprise given the time of year that is in it. The inclement weather may have had something to do with it as the low pressure which advanced from the southwest while we were out there could have moved birds on to another area ahead of us. 

As an example of how quiet it was, the seabird team set a new personal record of a full 90 blank minutes between sightings of different individual birds during a survey period on one of the days! A record they hope ever to break again!

That being said, many of the species present over the bank were of interest: Cory's shearwaters, great shearwaters, sooty shearwaters, pomarine skua and the first Leach's storm-petrels of the trip bringing the species total to 20. 

In other news, the first migrant landbird of the survey was seen yesterday in the form of a turnstone which circled the ship some 300km offshore. It was presumably heading south for the autumn from breeding grounds in Greenland (yes... for some birds autumn has begun!).

Cory's shearwater (c) John Power

Fulmars (note the 'blue' fulmar, top left) (c) Niall T. Keogh

Leach's storm-petrel (c) Niall T. Keogh

COTF6 Day 6: It Ain't Over Until The Fat Turtle Sings

As we make our way into Galway Bay to dock tonight, it's time to look back on yet another superb days surveying on board the R.V. Celtic Explorer in the waters off West Ireland.

It was both a busy night and day for the acoustic monitoring teams with the hydrophone picking up plenty of common dolphin whistles as well as some lively vocalisations from long-finned pilot whales. 

Common Dolphin clicks and whistles (c) Enda McKeogh

Our starting point over the Hovland Mound SAC at the North end of the Porcupine Seabight remained quiet enough for the first hour or so before large numbers of common dolphins with several calves started making their way towards the bow. During all this commotion, a separate group of 30 or so very active dolphins some distance ahead of the ship caught our attention. With behaviour and a breaching style suggestive of striped dolphin we decided to break track and investigate. A mixed group of both common dolphins and at least three striped dolphins then appeared on our port bow, showing incredibly well, allowing for some excellent photo opportunities (closer examination of which reveals 'foetal folds' also known as 'birth rings' on one of the striped dolphins, indicating its young age). It was a real treat to get such good views of this infrequently encountered species in Irish waters after our brief run in with them earlier in the week.

Striped Dolphin. Just look at how it bursts out of the water! (c) Jason McGuirk

Striped Dolphins. Note the prominent, slightly bulging and steep forehead (c) Rossa Meade

Striped Dolphins. Always acrobatic! (c) William Hunt

Common Dolphin (c) Roisin Pinfield

Later in the afternoon, a large sized and active group of common dolphins had with it an entourage of milling seabirds, namely sooty shearwaters, gannets, European storm-petrels and a circling pomarine skua. All indications of a mixed species feeding association on the go, the birds perhaps availing of fish pushed to the surface by the dolphins? Whilst scanning through the flocks of seabirds, that unmistakable shape of a leatherback turtle, complete with its ridged carapace and prehistoric looking head, came looming out of the water among them not more than 100 metres from the ship. A stunning view of an ancient and gnarly animal. Magic!

Leatherback Turtle (c) Hannah Keogh

Aside from the aforementioned leatherback turtle, more marine ‘megafauna’ was recorded again today such as a large ocean sunfish with lesser black-backed gulls in attendance (perhaps picking parasites off it?) and half a dozen or so albacore tuna breaching close to the ship.

Ocean Sunfish (c) Jason McGuirk

Seabirds were generally low in number yet again but the patch of feeding activity associated with the common dolphins and leatherback turtle in the afternoon certainly bumped up some figures. A Wilson’s storm-petrel showed well first thing this morning as it passed by close to our port side. A total of four very fine adult pomarine skuas complete with ‘spoons’ (i.e. their uniquely shaped tail streamers) flew right over the observation deck. New species added to the trip list today included a puffin, a black-headed gull and numerous great black-backed gulls. Other tallies in the form of a great shearwater, 20 sooty shearwaters, 19 Manx shearwaters, 58 European storm-petrels and 7 great skuas were noteworthy. 

Pomarine Skua (c) Jason McGuirk

Marine litter surveys continue (c) Jason McGuirk

In the final minutes of survey time for the seabird team, a totally unexpected migrant songbird landed on the railings just 1 metre beside the observers... a nightingale! The bird took flight and made its way out to sea before coming back and landing in the rescue boat on the deck! It then flitted about from here to there for about 10 minutes or so, not looking very settled at all, before flying back out to sea, never to be seen again. This all occurred some 40 nautical miles West of Loop Head, Co. Clare. Nightingales are a very rare passage migrant to Ireland with just 30 or so documented records to date. An amazing send off at the end of the trip! Additional new migrant birds on the R.V. Celtic Explorer included a merlin, a blackcap and a lone swallow which was seen circling the crow’s nest.

Nightingale on the R.V. Celtic Explorer (c) Rossa Meade

Nightingale in flight (c) Rossa Meade

Nightingale in flight (c) Rossa Meade

Nightingale in flight (c) William Hunt

Merlin on the R.V. Celtic Explorer (c) William Hunt

News of our killer whale sighting from a few days ago seems to have been a popular story with the media, receiving coverage in the national papers, radio and TV. Here's an article on the subject on BreakingNews.ie for those interested.