Tag Archives: Dolphins

A smooth encounter with a Porcupine’s back

By Rich Chiverrell

Thirty seven days ago we sailed from Southampton, a journey that has seen us tackle five of the target transects for the NERC Consortium Research Project Britice-Chrono. As the days and nights of hard work pass we have ticked the transects off one-by-one, T4 Irish Sea West – Celtic Sea (53 cores), T3 Irish Sea East (35 cores), T6 Donegal Bay (21 cores), T7 Malin Sea (43 cores). 06:44 hours Friday 22nd August the last of the transects bit the dust, 65 cores stretching from inner Galway Bay, the coast of Connemara out to the Outer Edge, the Porcupine Bank, many many miles of survey line and hundreds of dolphins (keeping Marion happy where is a mammal observer without mammals)……

T5 in the bag

T5 in the bag

Our strategy was to collect three survey transects radiating out from Galway Bay, the first involved our skirting the northern sector and sampling enigmatic ridges fronting the continental shelf break, recovering diamict and shells, but as we progressed west diamict proved harder to find, though we have had some successes. We wonder and debate what age is this glacial terrain? It could be old, very old? Or maybe not, I guess we will find out. Journeying landward we completed one of many criss-crosses of the large ‘Olex’ moraine that appears to front Galway Bay. Popularly named after a survey system fitted to ships, the Olex system collects sea floor morphological data and is fitted to many commercial and private vessels sailing waters around the globe contributing a commercial data collective and providing a valuable window on our sea floor. This moraine often mooted as the maximum limit, but some of the outer moraines we encountered and the shells within their sediments may challenge that conclusion. The terrain that caps the moraine is hard and we expend some time trying to capture datable materials. It feels a little like being between a rock and a hard place, but as night-watch passes the baton onto day-team and vica versa, we are all in the same boat…..

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Weather and sea state intervenes and interrupts our sampling, with the vibrocorer becoming too challenging to safely recover to deck. No rest for us, we head for calmer waters in the shadow of Connemara, with the Twelve Pins in view. A chance occurrence driven by the weather but very useful, as we collect vibro and piston cores from these waters recovering glacigenic materials and some inner marine datable materials that will link well with terrestrial fieldwork in the mountains and rocky lake-strewn lowlands of coastal Connemara. NOC team set the piston core record for the Cruise at just under 8m, we some very enigmatic coarse shelly units in stratified sands…. Eventually the seas relent and a grand voyage to the outer edges of Porcupine Bank is planned to test an extensive glaciations hypothesis, sadly we are confounded by sands, but there is certainly some diamict on the inner sectors of the bank that need explaining. Our final transect is our departure route from Galway Bay, southwest flanking the coastline of County Clare and across a series of moraines, potentially the southern equivalent of the ‘Olex’ moraine, more cores, more diamicts and shells ensue. We are complete 5 transects, 218 cores slightly over the pre-cruise conjectured 75 (?), ‘scientists!!!’ A very big thank you to the BGS and NOC core teams on both legs, the crew of the RRS James Cook for their friendship, good will, humour, company and fantastic support throughout this endeavour. The core length guessing competition has two winners: Stephen during the Day and Riccardo at Night. All that is left is our journey around southwest Ireland, crossing the Celtic Sea once again, but can we resist the lure of the moraines of Bantry Bay………….

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Cruise 1: meet our Marine Mammal Observer

By Marian McGrath
dolph
Hello everyone! It’s been one week since we joined the RRS James Cook in Southampton, even though we didn’t actually leave the port till Friday the 18th due to technical problems with the vibro corer. My role on board is as the Marine Mammal Observer (MMO). The role of the MMO is to ensure the safety and protection of marine mammals from man-made noise pollution in the ocean. This can damage or kill cetaceans which have very sensitive hearing. The Marine Mammal Observer (MMO) is required by law to be aboard any vessel which is carrying out seismic surveys within Irish waters. On this vessel, Sub Bottom Profiler seismic equipment and Multibeam echosounder equipment are being used. In unprotected marine areas an MMO is required to carry out a 30 minute pre Multibeam echo sounder and Sub Bottom Profiler watch followed by a 20 minute watch during the soft start. Sound activity cannot commence until the MMO gives clearance after the 30 minute watch. If marine mammals are spotted within 500m range of the equipment during this watch then a further 30 minute watch is undertaken till marine mammals have left the mitigation zone. If no marine mammals were seen within this time then a soft start would commence. Once the ramp up procedure is started there is no need to stop the equipment during night time hours. The Multibeam and Pinger systems remain active during the survey unless we are on a coring station for longer than an hour in which case they are switched off. They are also turned off during the mid-cruise port call in Killybegs.

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Marine mammal observations are carried out from the bridge. This gives the best view point of both sides and in front of the vessel. The equipment is always started during daylight hours to allow for MMO watches to be carried out prior to soft starts. Observations are undertaken using a reticular binoculars, a range finder and also by the naked eye. Distance to marine mammals is determined using this reticular binoculars and height above sea level. To determine the range one of the divisions present in the binoculars is placed on the horizon. A formula is then used to determine the distance of the mammal from the ship. The formula is: Distance (m) = (height of eye above sea level (m) x 1000/ no. of mils down from horizon). Throughout the duration of the survey, watches are undertaken throughout the day and any sightings are logged in a computer supplied by The Irish Whale and Dolphin Group. This will feed into a database which is constantly updated regarding location and numbers of various species. Throughout the day recordings are taken of precipitation, sea state, visibility, ship speed, water depth, cloud cover, latitude and longitude, wind speed and direction. So far on this survey Common Dolphins have been seen near the shelf edge of the Celtic Sea. First 4 adult dolphins were seen on the 21st July and later the same day 11 adults and one calf were seen.