Western European Shelf Pelagic Acoustic Survey 2016

Introduction (from the Scientists@Sea blog, follow link here for more information)

"The Western European Shelf Pelagic Acoustic Survey (WESPAS) is a new multidisciplinary research survey representing the largest single vessel acoustic survey program in Europe. WESPAS is the consolidation of two existing acoustic surveys (the Malin Shelf herring and the boarfish acoustic surveys) into one. This new survey will be undertaken onboard the RV Celtic Explorer over the coming six weeks covering shelf waters from Northern Scotland to northern Biscay. The primary aim of the survey is to determine the acoustic abundance of small pelagic fish, namely herring, boarfish and horse mackerel for use in stock assessment. The survey grid provides an opportunity for complimentary research to enhance the overall program providing important metrics on the drivers that influence pelagic fish distribution. As well as investigating fisheries, scientists onboard are also investigating marine water chemistry, sampling for plankton, undertaking visual surveys for marine mammals and seabirds and also surveying for whales and dolphins using passive acoustic monitoring (PAM). The survey will also be retrieving acoustic moorings deployed during the blue whiting acoustic survey in March as part of the ObSERVE-Acoustic program. All in all, an action packed survey ahead!"

During the first leg of WESPAS in late mid-late June, surveying for marine mammals and sharks was conducted by Hannah Keogh (Irish Whale and Dolphin Group) around the Hebridean shelf waters off West Scotland and Northwest Ireland. Below is a summary map of her observations during that period which included a sighting of the male killer whale known as 'John Coe' on 18th June near the island of Coll. This animal was seen near The Blaskets, Co. Kerry just nine days later (see here for more info).

WESPAS leg 1 sightings June 2016 (c) Hannah Keogh (IWDG)

(white-beaked dolphin, common dolphin, Risso's dolphin, killer whale, minke whale, humpback whale, grey seal and basking shark)

The second and third legs of the WESPAS survey will take in the waters off West Ireland including the Porcupine Bank and Celtic Sea as well as heading to the canyon systems west of Scilly/Brittany. During this survey period in July, a full team of marine mammal and seabird surveyors will be present from ObSERVE-Acoustic, Irish Whale and Dolphin Group, Marine and Freshwater Research Centre GMIT and MaREI/University College Cork.

Survey route for the second and third legs of WESPAS in July 2016 within the red box

This diverse group of seasoned surveyors includes several members of the Cetaceans on the Frontier team, hence why we will be hijacking the COTF blog here to bring you sightings updates from the WESPAS survey this July!

Day 1 sightings: Monday 4th July 2016

The RV Celtic Explorer left Galway docks at 03:30 this morning and began making its way north off the coast of Connemara and Mayo towards the start of the survey transect lines

Black Rock lighthouse and Achill Island (c) Niall T. Keogh

Strong northerly headwinds and a sea state of 5 made survey conditions challenging and no marine mammals were observed. Some dolphin whistles were picked up on the hydrophone however so the honour of 'first blubber' goes to the passive acoustic monitoring (PAM) operators!

The seabird team had a good day for 'getting the eye in' with 13 species recorded: gannet, fulmar, manx shearwater, sooty shearwater, European storm-petrel, pomarine skua, kittiwake, great black-backed gull, lesser black-backed gull, Arctic tern, puffin, razorbill and common guillemot.

 Manx shearwater, one of the most abundant species seen today as we passed by several of their west coast breeding sites (c) Niall T. Keogh

A juvenile and adult razorbill (c) Niall T. Keogh

Sighting of the day however was "RESCUE118" the Irish Coast Guard Sikorsky-S92 duty helicopter, operating out of Sligo, which came over to RV Celtic Explorer in order to carry out some training exercises while we were well to the northwest of The Mullet Peninsula.

"RESCUE118" in action (c) Niall T. Keogh

COTF4: The Graveyard Shift

A well planned research expedition makes use of every available minute. The old adage ‘time is money’ definitely rings true for offshore scientific surveys. In order to make the most of this ship time we employ surveying and sampling techniques which don’t rely on daylight. These can include oceanographic mapping, video surveys for pelagic fauna and continuous sampling for plankton & microplastics.

My role onboard revolves around plankton sampling for which we make use of a CTD probe (which measures conductivity, temperature & depth, amongst other parameters). This probe is dropped vertically while the ship is stationary. It provides us with a good way of taking water samples, mounting plankton nets and other equipment such as a video camera system all at the same time. In addition to this it allows us to assess the different water masses from which we are sampling. The water below us is often stratified, with the strata having different salinities, temperatures and oxygen concentrations. The diversity of strata leads to diversity of organisms. We can measure photosynthesis (eg. phytoplankton) in each of these strata, as well as taking water samples at specific depths. This allows us to assess the origin of what we find in water samples, as each water mass, with its own distinct signature, comes from a different area (for example Mediterranean and Arctic waters can be distinguished from each other).

CTD being lowered for sampling (c) Emilia Chorazyczewska

CTD read out (c) Emilia Chorazyczewska

Plankton are sampled continuously on these vertical tows, and give us an idea of the various groups living in a column of water. So far on Cetaceans on the Frontier 4, our deepest drop has been to a depth of around 4.5km. During Cetaceans on the Frontier 3 in 2012, these small samples went on to be involved in studies involving genetic analysis of plankton and understanding how cetaceans fit into food webs using stable isotope analyses (their trophic ecology). This time around, despite some limitations related to weather, we have managed to take plankton samples for trophic studies of fish, sampled water to look for microplastics, aided in a test of acoustic releases for sensor moorings and tested an experimental camera system for studying plankton.

 Purpose built, deep sea camera (c) Fergal Glynn

 Plankton sample; a Euphausiid krill & two copepods (c) Fergal Glynn

There’s no working around the weather at the moment unfortunately. Even after we changed methods to try to deal with the swell and wind, we had to temporarily suspend sampling when it reached a solid seven (rather more wet and windy than solid!). We look forward to getting out and dropping some more sampling stations when we make a break for sea.

Watch this space for more updates from the graveyard shift.

Fergal Glynn
(Queen’s University Belfast)

COTF3 Night 4: Exploring The Deep

Monday night 4 sampling stations were covered by the zooplankton team. The maximum depth that was reached was 2,916m. Similar species to the previous nights were found again including barrel salps (jellies), polychaetes (worms), isopods, amphipods, euphasiids (krill) and chaetognaths (arrow worms).

The only surface animals spotted on Monday night were two garfish.

Zooplankton sample (c) Lilian Lieber

An interesting CTD (conductivity, temperature, depth, oxygen and fluorescence sensor) profile was generated on Monday night on the final station which covered a depth of 2,916m. The profile showed the differences in surface waters and those at depth. These readings can be used to determine the origin of water masses. A low oxygen signal at 800-1000m corresponded to a peak in salinity values at the same depth. This is most likely the Mediterranean water signal, a water mass which originates in the Mediterranean and exits through the Straits of Gibraltar. 

CTD read out at 2,196m

Today's blog contributors: John Power, Catherine O'Sullivan and Fergal Glynn (zooplankton team)