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

CSHAS 2016: Megafauna madness over the Celtic Deep

Day 15: Friday 21st October

Skipping ahead a bit here since the last blog update but doing so in order to share some notes and pics from an absolutely superb day spent watching an impressive abundance of 'marine megafauna' over the Celtic Deep, well to the south of Co. Wexford.

As the first rays of dawn broke, a peek out the cabin porthole revealed a flat calm sea and visibility clear to the horizon line. After a quick breakfast we were on deck and ready for action. Within minutes the seabird team picked up a small group of harbour porpoise off our port side which when radioed in to the marine mammal team was met with a reply of "we're watching more off to our starboard!". After trying (and failing) to spot some porpoises during the inshore legs of our transect lines off Cork, Waterford and Wexford over the past two weeks, we were surprised to finally encounter them this far offshore and what's more, we weren't expecting to see so many! Every time we scanned we seemed to find more and more porpoises and at one stage a single scan across the view-shed revealed no less than 58 animals! Final tallies for the day almost reached 200 animals!

Consulting with the Marine Institute fisheries scientists in the lab who were monitoring the underwater acoustic images being recorded by the ship, it was clear that there was a lot of activity going on below us with masses of plankton, krill, forage fish (herring) and even a plethora of bluefin tuna showing up! This abundance below water was certainly mirrored at the surface and in addition to the harbour porpoises we noted lots of common dolphins, racked up no less than fifteen sightings of Minke whales, two fin whales (one of which crossed right in front of the bow at close range), a single humpback whale, an Atlantic grey seal, several breaching bluefin tuna and even some blue sharks swimming at the surface (being able to see the latter is a testament to how calm the conditions were).

No doubt there was some duplication in sightings at play due to the close proximity of the parallel survey transect lines, yet the marine mammal observers in the crow's nest still amassed an impressive total of 78 sightings involving up to 500 animals!

After a ten hour day out on deck we are all a little tired and more red in the face than usual so I'll finish up and let the following selection of pics tell the rest of the story...

Ideal conditions over the Celtic Deep (c) Niall T. Keogh

Harbour porpoise (c) Niall T. Keogh

Blue shark 'knifing' at the surface (c) Niall T. Keogh

Blue shark clearly visible underwater! (c) Stephanie Levesque

Bluefin tuna (c) Niall T. Keogh

This common dolphin showed exceptionally well, actively surfacing just metres away from the ship. Closer examination of the pics suggest it may be unwell. The protruding rib-cage and sunken appearance behind the skull (known as a 'post-nuchal depression') indicate that it is in poor body condition (c) Niall T. Keogh

A couple of perfectly healthy looking common dolphins (c) Meadhbh Quinn

Minke whale showing the typical, falcate (sickle shaped) dorsal fin (c) Gary Kett

Minke whale showing a straighter, more erect shape to the dorsal fin (c) Meadhbh Quinn

This humpback whale spent quite some time logging (resting) at the surface (c) Meadhbh Quinn

But after a while the humpback eventually treated us to a nice tail-fluke! (c) Meadhbh Quinn

Fin whale surfacing sequence (c) Meadhbh Quinn / Niall T. Keogh

Irish Whale and Dolphin Group marine mammal observers: Meadhbh Quinn and Gary Kett

Marine and Freshwater Research Centre GMIT seabird observers: Stephanie Levesque and Niall Keogh

Celtic Sea sunset (c) Gary Kett

CSHAS Days 5 to 10: Sunny Southeast and the Celtic Deep

Day 5 to 10 sightings: Tuesday 11^th to Sunday 16^th October

We have been playing a game of cat and mouse with some of the largest animals in the ocean over the past week… the whales are currently winning out!

While enjoying excellent weather off Cork during the first few days of the survey, both fin and humpback whales were being seen from headlands in West Waterford (many thanks to Andrew Malcolm for the updates!) but by the time we reached this area the weather had deteriorated to the point such that no large whales were spotted. 

High pressure conditions with easterly winds allow for fantastic visibility and a stunning mix of colours at sunrise and sunset (c) Usna Keating

Similarly, while enjoying the gannet spectacle over the Celtic Deep, our fellow seabird and cetacean surveyors on RV Cefas Endeavour (taking part in the Peltic Survey) encountered up to 12 fin whales on their transect lines just east of us! We saw two Minke whales ourselves that day and as delightful as they are, we were somewhat dismayed to learn that their larger cousins eluded us once again.

The next day, while making our way north along a transect line towards the Saltee islands off Co. Wexford, excellent sea conditions and visibility allowed us to spot two sets of large baleen whale blows several kilometres off which most likely came from fin whales due to the tall and narrow nature of the blows. Another large baleen whale blow was then recorded over the Celtic Deep well to the northwest of Cornwall but the animals body (and thus identity) remained hidden by heavy swell. Slow progress! 

Rainbow over Great Saltee (c) Niall T. Keogh

Common dolphins have thankfully remained abundant, ensuring Meadhbh has been busy racking up the sightings from the crow’s nest. Mostly small groups noted but one sighting of 60+ animals bounding towards the ship with great enthusiasm in rough seas made for quite the sight. A small group of bottlenose dolphins seen on the inshore section of a transect line to the east of Cork Harbour were too distant to get usable dorsal fin pics for photo-ID purposes but it is likely that they are from the 'coastal' group, one of three populations known to occur in Irish waters. We’ve also had a sighting of unidentified dolphins over the Celtic Deep which were most likely bottlenose again.

Common dolphins (c) Niall T. Keogh

Bluefin tuna and Portuguese man o’ war continue to be seen here and there; attempts at capturing breaching tuna on camera are slowly but surely getting better…

Breaching bluefin tuna (c) Niall T. Keogh

A couple of stowaways were also reported to us by the crew! Recently fledged juvenile European storm-petrels out at sea for the first time can become disorientated during rough weather, get attracted to the lights of ships, land on the deck and then find it difficult to get airborne again. Two such birds were found nestled in the corners of the deck and whilst initially looking a little bedraggled and waterlogged, were allowed some time to rest and dry off in our special ‘stormy hotel’ (a box!) before being released safely overboard the following morning. With any luck they will survive and live long and healthy lives (some storm-petrels are known to reach 30 years old!).

Juvenile European storm-petrel (c) Niall T. Keogh

The seabird list for the trip now stands at 25 species after cormorant, grey phalarope, black-headed gull and little gull were added over the past few days. Guillemots and gannets remain by far our most abundant species recorded each day whilst plenty of interest is being added by good numbers of great skuas, yet more yellow-legged gulls (survey tally now at seven birds), occasional sooty shearwaters, puffins, Arctic skuas, small flocks of European storm-petrels, a single Balearic shearwater east of Hook Head and fantastic views of great shearwaters following the ship while some 35 nautical miles northwest of St Ives, Cornwall.

Two grey phalaropes seen just a few miles off Helvick Head (c) Niall T. Keogh

Great shearwaters (c) Niall T. Keogh

Sooty shearwater (c) Niall T. Keogh

Most great skuas seen in the Celtic Sea at this time of year are in the midst of active wing moult (c) Niall T. Keogh

Smaller numbers of pristine juvenile great skuas have also been noted (c) Niall T. Keogh

Adult yellow-legged gull following the ship over the Celtic Deep (c) Niall T. Keogh

1st calendar-year yellow-legged gull (c) Niall T. Keogh

Arrivals of migrant landbirds continued throughout with more meadow pipits, alba wagtails, swallows, redwings and chiffchaffs noted plus additions of skylark, song thrush, starling and even a tiny goldcrest (arguably one of the world’s greatest migrants… a wee bird capable of making almost 1,500km long journeys in just 20 days, across open water and weighing in at just 5 grams!).

Song thrush on RV Celtic Explorer (c) Niall T. Keogh

Chiffchaff on RV Celtic Explorer (c) Niall T. Keogh