WESPAS Days 20 to 25: southern Celtic Sea to northern Bay of Biscay

Day 20 to 25 sightings: 23rd to 29th July 2016

After somewhat of a lull in cetacean activity in the mid Celtic Sea region, things started hotting up (literally!) as we approached the southern reaches of the Irish offshore territory and into UK and French waters. The sea surface temperature peaked at around 18°C and the ocean sunfish were out in force, as were common dolphins, with several groups seen every day ensuring the marine mammal observers were kept busy. We also recorded several breaching tuna, which looked to be bluefin and albacore. Our hoped for leatherback turtles didn't materialise however.

The outermost survey transect lines brought us close to or just over the continental shelf edge, an area of high productivity where several fin whales and even a single striped dolphin were noted. While surveying near the shelf edge along the northern end of the Bay of Biscay one evening, we spotted two very tall blows out towards the horizon line on our starboard side, presumably from fin whales. Soon after, another group of three fin whales crossed the path of the ship ahead of us from port to starboard, offering fantastic views.

Hard to beat good looks at the second largest animal on earth! 

Fin whale (c) William Hunt

 Fin whale (c) William Hunt

Fin whale (c) William Hunt

Fin whale (c) John Power

(you can just about make out the white colour to the right-hand side of the lower jaw in this pic, a diagnostic ID feature for the species)

We had some really nice sightings of bottlenose dolphins too, both near the shelf edge and also over the shallower shelf waters. Each group seemed to give the ship a wide berth, travelling past at distance. We tried to take as many pics as possible to see if we can match them to any known group (bottlenose dolphins with distinctive notches, scars and colourations on their dorsal fins are catalogued across Europe). It would be great to find out which group these animals belong, 'offshore' or 'coastal'?

Bottlenose dolphins (c) William Hunt

Common dolphin (c) William Hunt

Common dolphins (c) Mick Marrinan

Ocean sunfish (c) William Hunt

Sightings of cool marine wildlife have not just been limited to daylight hours. While on transect lines, the ship stops on station at night from midnight to 4am as part of the method for surveying boarfish. During this time a whole manner of life is attracted to the waters around the ship, illuminated by the lights. Fish such as saury start appearing in their droves to feed on gathering plankton which in turn attract predatory species like garfish, blue sharks, common dolphins and even seabirds such as fulmars and European storm-petrels (plus a grey phalarope one night circling the ship, calling!). 

This nocturnal wildlife spectacle has provided the night shift scientists and crew with endless entertainment (the blue sharks stealing the show, hands down). Even some of us day shift observers had to stay up way past our bed time in order to witness it!

Blue sharks (c) John Power

Blue shark (c) John Power

European storm-petrel circling RV Celtic Explorer at 2am (c) Niall T. Keogh

The seabird list finished up on a total of 26 species with the latest additions being Barolo shearwater, grey phalarope and yellow-legged gull. 

Barolo shearwater (which breeds on Atlantic islands such as the Canaries) was a real highlight as it is a rarely observed species around Irish and UK waters but more often seen in the Bay of Biscay, so the bird we saw travelling north with a Manx shearwater just inside the UK offshore territory some 270km southwest of Scilly was perhaps just about on the edge of its perceived regular range, although it seems we have a lot more to learn about their occurrence closer to home as this tracking study has shown.

A flock of 17 grey phalaropes was flushed ahead of the ship on the evening with lots of fin whale activity near the shelf edge along the north side of the Bay of Biscay. These pelagic waders (which feed on zooplankton) will already be on their way south to wintering grounds off the west coast of Africa. On examining pics of the flock, it appeared that quite a few females were present. Grey phalaropes breed in the High Arctic, where the males incubate the eggs and safeguard the chicks during the breeding season while the females leave soon after the eggs have been laid so it is not surprising that we have seen a flock of mostly females this far south already. Their work is done!

A quick check of the gull flock following the ship while west of Brittany yesterday afternoon produced a single fresh juvenile yellow-legged gull, as expected, but enjoyed immensely by the gull enthusiasts on board (...enthusiast, to be precise!).

Otherwise, the past week for the seabird team has been spent soaking up excellent views of yet more Cory's shearwaters and great shearwaters, a very good showing of European storm-petrels and some long-tailed skuas. A few more Wilson's storm-petrels were also seen, bringing the tally for the trip up to 13 individuals. 

Cory's (left) and great (right) shearwaters (c) William Hunt

Cory's shearwater (c) William Hunt

Great shearwater (c) William Hunt

Juvenile lesser black-backed gull (c) Niall T. Keogh

 Gannet (c) William Hunt

Gannets (c) William Hunt

After 25 days at sea, the Western European Shelf Pelagic Acoustic Survey (WESPAS) has come to an end. We are docking in Falmouth in Cornwall this morning from where we will make our way home to Ireland, giving us plenty of time to reflect on the fantastic marine species which we have had the privilege of seeing over the past few weeks. From here the RV Celtic Explorer will make its way to Germany to  undertake another survey.

We'll finish up with a pic of the final species list for the survey and a heartfelt thanks to Chief Scientists Ciaran O'Donnell and Graham Johnston (Marine Institute) for their continued support of offshore marine mammal and seabird surveys and to the officers and crew of RV Celtic Explorer for all their valued assistance throughout the cruise. Until next time... 

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