BWAS 2017: End of Survey

Blue Whiting Acoustic Survey 2017 Week Three: Saturday 1st to Thursday 6th April

The final days of BWAS 2017 were largely uneventful, at least in terms of sightings, due to the arrival of a low pressure system which created some rough seas for our journey back home to Galway.

A couple more sightings of long-finned pilot whales on the last stretch of survey transect between the Rosemary Bank and the Hebridean shelf were the last cetacean sightings of the survey, after which we turned south and headed through The Minch. This is an area where we would have hoped for the likes of white-beaked dolphin, Risso's dolphin and even killer whale but unfortunately we found ourselves battling slowly into a head-on southerly wind and rough seas making carrying on with survey effort a somewhat futile exercise.

Our arrival into Galway was met with the final sighting of the trip overall, that of 'Nimmo' the apparently resident bottlenose dolphin which was seen foraging at the mouth of the River Corrib just off the tip of Nimmo's Pier. It is likely that it will remain here through the spring and perhaps as late as July so if you are in Galway, make sure to pop down for a look (and report any sightings of it to IWDG).

BWAS 2017 species lists

'Nimmo' the Galway Bay bottlenose dolphin (c) Andrew Power

So another successful survey overall with plenty of seabirds and cetaceans recorded over some fantastic offshore habitats during what is always a very enjoyable research cruise. Many thanks to our Chief Scientist, Graham Johnston (Marine Institute) for the opportunity to come along again and continue the survey collaboration and further thanks to Captain Denis Rowan and the rest of the RV Celtic Explorer crew for their help and hospitality over the past three weeks.

We'll sign of with a selection of pics of the scientists and crew of RV Celtic Explorer and some of the wildlife observed during BWAS 2017...

MMO on watch in the crow's nest (c) Carlota Vialcho Miranda

Crow's nest views (c) Aude Benhemma-Le Gall

Sperm whale (c) Aude Benhemma-Le Gall

Common dolphin (c) Aude Benhemma-Le Gall

Long-finned pilot whales (c) Aude Benhemma-Le Gall

Fin whale (c) Aude Benhemma-Le Gall

A well wrapped up seabirder! (c) Aude Benhemma-Le Gall

Gannet (c) Aude Benhemma-Le Gall

Great black-backed gull (c) Aude Benhemma-Le Gall

PAM operator (c) Carlota Vialcho Miranda

CTD being deployed to collect information on water temperature, salinity etc. (c) Aude Benhemma-Le Gall

Crew getting ready to bring in the net (c) Aude Benhemma-Le Gall

Catch of blue whiting on the deck (c) Aude Benhemma-Le Gall

Blue whiting (c) Aude Benhemma-Le Gall

Measuring fish (c) Aude Benhemma-Le Gall

Creatures from the murky depths! (c) Aude Benhemma-Le Gall

Squid (c) Niall T. Keogh

Sunset (c) Carlota Vialcho Miranda

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

Blue Whiting Acoustic Survey (BWAS) 2017

Introduction

The Marine Institute's RV Celtic Explorer will once again be taking part in the Blue Whiting Acoustic Survey (BWAS) this year (18th March to 7th April) over the Rockall Trough, starting with the Porcupine Bank in the south and working north to the Rockall Bank and beyond before heading back to Galway via the west coast of Scotland.

This fisheries acoustic survey will assess the spawning stock of blue whiting which can be found in the deep waters along the Rockall Trough in early spring. A team of observers will be on board again this year in order to carry out a survey of marine mammals and seabirds found in this region. 

Proposed survey transects for BWAS 2017. The RV Celtic Explorer route is marked in green  (click to view larger image) (c) Marine Institute

Sean O'Callaghan is our dedicated Marine Mammal Observer (MMO) for the trip and he will carry out visual surveys for marine megafauna (whales, dolphins, seals, turtles etc) for the Irish Whale and Dolphin Group (IWDG) from his perch in the crow's nest, continuing the long term monitoring project during BWAS since 2004 by the group. Sean is in his third year of the Applied Freshwater and Marine Biology degree at GMIT and is no stranger to marine mammals, having been involved with previous IWDG surveys both inshore and offshore on RV Celtic Explorer, RV Celtic Mist and RV Song of the Whale over the past year alone as well being involved with the new IWDG North Kerry Local Group.

Surveying for cetaceans will not be limited to just visual detection as a hydrophone will be towed underwater behind the ship while travelling along the transect lines. This will allow our Passive Acoustic Monitoring (PAM) operator Aude Benhemma-Le Gall to listen out for the calls made by whales, dolphins and porpoises. Aude is based in Galway this year to work on her thesis as part of the International Master of Science in Marine Biology and Conservation (EMBC+) which will focus on static acoustic monitoring of harbour porpoise at the Galway Bay Marine and Renewable Energy Test Site.

The seabird team from Marine and Freshwater Research Centre, GMIT is led by PhD student Niall Keogh who is collecting data on offshore seabird distribution, abundance and behaviour in Irish waters through visual surveys for the fourth year in a row now during BWAS. This will be the first of four surveys on RV Celtic Explorer which Niall will join this year in order to undertake seabird surveys for his research. Carlota Vialcho Miranda is another EMBC+ student working on her thesis in GMIT (distribution, abundance and habitat use by the coastal population of Irish bottlenose dolphins) and will be joining the seabird team this year with Niall for her first experience of Atlantic seabirding! 

The BWAS 2017 marine mammal and seabird team (L-R): Aude, Niall, Carlota and Sean

The RV Celtic Explorer is one of four research vessels taking part in the Blue Whiting Acoustic Survey, with vessels from Norway, the Faroe Islands and the Netherlands also involved. William Hunt is on the Norwegian vessel (FV King's Bay) as MMO for MaREI with Laila Higgins on there also through the Foreign Vessel Observer Scheme. The Dutch vessel (MV Tridens) will also have Ailbhe Kavanagh (MaREI) as MMO and Gary Kett as the representative for the Foreign Vessel Observer Scheme. So between us all we should manage some great coverage of the Rockall Trough area over the next three weeks.

Blog readers can stay updated with our progress and view the latest pics and sightings over the course of the survey by checking in every few days here on the blog, by liking our Facebook page or by following the #BWAS2017 and #RVCelticExplorer hashtags on Twitter. 

The marine mammal species we typically see during BWAS trips are those which prefer the deep water habitats around the Rockall Trough to the west of Ireland and Scotland. These include long-finned pilot whale (usually the most abundant species seen) and sperm whale (frequently seen) as well as occasional sightings of the mysterious beaked whales (Sowerby's and Cuvier's beaked whales have been recorded during BWAS in recent years). Along the slopes of the continental shelf edge we expect to see fin whales and have been lucky with sightings of striped dolphin and white-beaked dolphin in such areas last year. Over the shallow shelf waters we would hope for Minke whale, common dolphin, harbour porpoise and grey seal. Killer whales were seen during BWAS 2013 and a repeat performance would be most welcome!

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

Common dolphin (c) Niall T. Keogh

White-beaked dolphin (c) Niall T. Keogh

Fin whale (c) Niall T. Keogh

Sperm whale blow (c) Niall T. Keogh

Sperm whale (c) Niall T. Keogh

Seabird species diversity during BWAS is generally found to be lower than on other survey trips which occur later in the year (especially in autumn). During March and April, most of our seabirds will be preparing for the approaching breeding season and as such might already be back at or close to their colonies. Furthermore, those species which would have migrated here from further afield for the autumn are probably already back at their own breeding grounds in the Mediterranean or sub-Antarctic. That being said, we can expect to see an interesting mix of species over the next few weeks as the tail end of the winter season changes into spring.

Fulmars, gannets and kittiwakes will make up the large bulk of the birds recorded offshore, where they will be actively foraging in order to get themselves into good condition for breeding. Small numbers of Manx shearwaters, great skuas and lesser black-backed gulls will be seen most days, having spent the winter further to the south and now making their way back north to their colonies. A handful of scarcer Arctic breeders such as little auk, glaucous gull and pomarine skua should be encountered too and we sometimes record more unusual species for the time of year such as great shearwater, sooty shearwater and Leach's storm-petrel which would be more associated with late summer and autumn in Irish waters. 

Fulmar (c) Niall T. Keogh

'Blue' fulmar (right-hand bird) (c) Niall T. Keogh

Gannet (c) Niall T. Keogh

Great skua (c) Niall T. Keogh

Glaucous gull (c) Machiel Oudejans

Little auk (c) Niall T. Keogh

As spring migration of birds gets underway, we can also expect to see some terrestrial species on or around the ship while offshore. This often happens during periods of bad weather (mist, rain, high winds) when birds can become tired or disorientated and land on the ship to rest or circle it in flight. Usually we will see species which are on their way to Iceland for the breeding season and those which land on the ship are often songbirds such as redwing, meadow pipit or wheatear, which can be brought down by bad weather. Conversely, flocks of pink-footed geese or whooper swans can be seen passing overhead in V-formation on clear, sunny days. From time to time something more unusual can turn up, such as bizarre sightings of water rail and collared dove during previous surveys which were well away from the nearest point of land. These are thought to be birds which migrated too far past the west coast (known as 'overshooting') and usually occur when easterly winds prevail. 

Redwing (c) Inge van der Knapp

Snow Bunting (c) Larry Manning

Willow Warbler (c) Niall T. Keogh

Water Rail (c) Niall T. Keogh