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

WESPAS Days 14 to 19: The Celtic Sea - a song of sun and fog

Day 14 to 19 sightings: 17th to 22nd July 2016

After the hectic day off the Blaskets on 16th July (see previous blog post), we made for Castletownbere in West Cork to carry out a mid-cruise crew change and take on some fresh provisions (which included a new coffee machine and fresh bananas!). Here we said goodbye to Dr Joanne O'Brien and Killian Coakley (GMIT) and said hello to William Hunt (MaREI/UCC) who joins the marine mammal observer team for the remainder of the trip.

The Marine and Freshwater Research Centre GMIT/Irish Whale and Dolphin Group team (from left to right): Sean O'Callaghan, Mick Marrinan, Killian Coakley, Dr Joanne O'Brien, Niall Keogh and John Collins

William Hunt (MaREI/UCC) on duty in the crow's nest

On leaving Castletownbere, we were treated to some nice sightings at the mouth of Bantry Bay just west of Sheep's Head. Common dolphins were plentiful, surfacing regularly among flocks of Manx shearwaters, auks and European storm-petrels and interspersed among these, a couple of minke whales, harbour porpoise and Atlantic grey seals.

Just as we cleared the bay, the dreaded fog set in, something which we were to be be plagued with for the next few days. This limited our survey effort during daylight hours with visibility often down to less than 100m. What made it all worse was that we could tell that just beyond the fog, somewhere, was bright sunshine and calm seas! 

Minke whale (c) Mick Marrinan

Common dolphins (c) John Collins

In time the conditions improved and as we made our way further offshore along the southbound survey tracklines into the Celtic Sea. The fog began to dissipate and we got our fair share of the glorious weather which everyone back home was out enjoying at the same time. And it was hot! 

With the wind at our backs and a following sea, we were fortunate to have a couple of days of superb survey conditions which produced some surprising sightings. Cetacean and seabird numbers were relatively low but the light easterly winds associated with the high pressure allowed some unusual migrants to make their way to the ship including a bat which spent some time flying around the crow's nest approximately 102km southeast of Galley Head, Co. Cork! Pics were posted online to see if it could be identified but without some clear shots of the ear and exact measurements of the wing it is unlikely that the issue will be resolved 100% (but thanks to everyone who made suggestions).

This follows on from a record of what is thought to have been a Leisler's bat, also present on RV Celtic Explorer at sea south of Cork in October 2015, so this sighting is not without precedent.

In addition to turnstone and whimbrel which were recorded west of Galway earlier on during the trip, other terrestrial migrants seen around the survey vessel in the Celtic Sea included a flock of 4 dunlin, a common swift (looking very out of place), a lost racing pigeon and a silver y moth!

Bat species (c) Niall T. Keogh

Racing pigeon (c) Niall T. Keogh

Quite a few jellyfish about too including mauve stinger (Pelagia noctiluca), compass jellyfish (Chrysaora hysoscella) and by-the-wind sailors (Velella velella). Lots of sightings of ocean sunfish also, including a group of three together and even some smaller individuals seen breaching fully out of the water! These oceanic wanderers eat jellyfish so looks like it's good times for them at the moment.

Velella velella (c) Niall T. Keogh

It has been an exciting few days for the seabird team with rare or scarce species dominating the tallies. We are out here at the perfect time of year for recording cool seabirds such as Cory's shearwater, great shearwater and Wilson's storm-petrel. Several hundred of the shearwaters have been noted, along with several instances of Cory's shearwaters tracking foraging groups of common dolphins. Fantastic to see these two top marine predators in close association, working the same aggregations of pelagic fish.

Among the flocks of European storm-petrels dancing over the water, a few Wilson's have been picked out (much to the delight of the observers) and while skua numbers have been low, all four expected species have been seen: great, pomarine, Arctic and long-tailed.

The seabird list for the survey is now up to 23 with the most recent additions being shag, common tern and long-tailed skua.

Great skua (c) Niall T. Keogh

European storm-petrels (c) Sean O'Callaghan

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

Great shearwater (c) Niall T. Keogh

Cory's shearwaters (c) Niall T. Keogh

Occupational hazard... airborne gannet poo hitting the crow's nest
(and the marine mammal observer!)

WESPAS Day 13: Blaskets Bonanza!

Day 13 sightings: 16th July 2016 

We hit the mother-load today along our survey tracklines to the west of the Blasket islands, Co. Kerry!

The day started with a group of 15 long-finned pilot whales on the eastern edge of the Porcupine Seabight some 70km NW of the Blaskets. This was soon followed up by a sighting of a blow from a large baleen whale.

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

As we approached the Blasket islands from the west we started picking up quite a few groups of common dolphins, a Cory's shearwater and a great shearwater.

Cory's shearwater (c) Niall T. Keogh

As we got to within 15km southwest of the Blaskets we entered a period of crazy cetacean and seabird feeding activity which lasted over an hour and included 11 minke whales, c250 common dolphins, c40 bottlenose dolphins, 2 harbour porpoises, several Atlantic grey seals and thousands of European storm-petrels, Manx shearwaters, puffins and guillemots along with a few sooty shearwaters, great skuas and a pomarine skua thrown in for good measure.

We didn't know which way to look! 

Minke whale surfacing sequence (c) John Power

Common dolphin (c) Mick Marrinan

Atlantic grey seal (c) John Collins

Manx shearwater (c) Niall T. Keogh

European storm-petrel (c) John Power

Unfortunately the weather sorted that out for us soon after and the visibility reduced to less than 100m. We couldn’t see the Skelligs even though we passed right by them!

An Tiaracht shrouded by misty cloud (c) Niall T. Keogh

One of our marine mammal observers on the ship, Sean O’Callaghan (GMIT), hails from The Kingdom and gives us a local’s perspective on the event:

“The Blaskets were brimming with marine life yesterday afternoon when the Celtic Explorer headed East by Inishvickillane before turning off into thick mist along the Southern side of the outer bay.

It was the calmest conditions I've ever been out there in and shortly after passing the Foze rocks the seabird life began to increase in numbers with hundreds of European storm-petrels zipping around, revealing the presence of a bait ball along with the common dolphins and single Minke whale feasting on the fish!

Cetacean and seabird feeding frenzy: minke whale (centre) flanked by Manx shearwaters and common dolphins (c) John Power

Puffins began to appear in large rafts bobbing on the surface the further east the Explorer cruised. Some harbour porpoises (the ninth species for this survey) briefly appeared before disappearing again.

Adult and juvenile puffins (c) Niall T. Keogh

Puffin escaping from the ships track! (c) John Collins

Juvenile and adult guillemot (c) Niall T. Keogh

Common Dolphins and minke whales consistently kept appearing in increasing numbers for a time off Inishvickillane but the appearance of some 40 bottlenose Dolphins was the highlight for me.

They surfaced slowly ambling towards the ship for a time but turned around 300m away where one of the Dolphins began to tail slap the water. After looking at some of my dodgy photos of these Dolphins, there was at least one calf present. 

Bottlenose dolphins (c) Niall T. Keogh

Bottlenose dolphins (c) John Power

When the Explorer turned to head South West, the mist that had lifted during the afternoon descended again where you wouldn't see anything unless the animals came to you as the case was when two bunches of Dolphins appeared briefly later that evening.

Unfortunately the two humpbacks that were in the area the previous day weren't encountered but in my biased view, it's been the best day so far on this survey!”

Gulls resting on the bow of RV Celtic Explorer (c) John Power

Great black-backed gull (left) and lesser black-backed gulls (right) (c) Niall T. Keogh