Cruise 1: meet our Marine Mammal Observer

By Marian McGrath
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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.

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