AUGUST 26 to September 11 RV Langseth MMO cruise: MMO observation during geophysical research

On August 26 the Ocean Botoom Seismometer (OBS) drops were completed and we commenced our full visual and acoustic monitoring. We had a final meeting with the PIs and techs to ensure everybody was clear on how the mitigation measures were to be implemented. Prior to turning on the airguns two of the MMOs did their visual watch using the Big Eyes, small binoculars and naked eye for 60 minutes and one of us listened acoustically for marine mammals at the PAM station. After completing the 60 minute watch without a sighting the techs began to ramp up the guns (gradually increase the airgun sound level over ~35 minutes).

The safety zone for this survey was very large (7.7 km) so while the airguns were firing our visual watches consisted of rotation between Big Eyes and naked eye/small binoculars every 15 minutes to ensure we didn’t tire from constantly looking through binoculars. We also utilized a PAM (Passive Acoustic Monitoring) system (CIBRA Workstation) to acoustically detect marine mammals. We listened for marine mammal calls and kept watch for those out of our hearing range using the PAM monitor at the PAM station, which shows the sound spectrograph, in the main lab. Once the guns were at the full sound level we did not need to clear the area again, unless they were shut down due to a marine mammal sighting or they were turned off for more than 9 minutes i.e. for maintenance, but we maintained watch of the area to ensure no marine mammals entered the safety zone. Our full watches consisted of 9 hours of visual and PAM spread throughout the day which meant we spent a lot of time running up and down between the tower and the main lab. To entertain myself when I wasn’t on watch I usually checked my email on the very slow internet connection, read or watched a movie in the ship’s theatre.

One of a pair of hitchiking wrens who appear to have come offshore with us from the coast

The deck crew busy cleaning around the stacks in rolling seas!

John and Meghan on visual watch

Joe on visual watch

The sunsets were beautiful when the fog and clouds cleared!

Moonrise at Endeavour MPA

And another beautiful sunset!

The MMO tower at sunset

The Big Eyes...at sunset!

Fortunately for the science crew we didn’t need to shut down the airguns due to sightings; the guns functioned well throughout the survey and we had no marine mammal sightings. This was good because it meant that no marine mammals were likely within range of the 160 dB zone of the airguns but it is possible that our lack of sightings was also due to behavioural avoidance of the area (paper on impacts of anthropogenic noise). In addition to following mitigation measures set by both the Canadian and US government August and September were chosen as survey months because it is the time of year endangered species, such as the Blue Whale (Balaenoptera musculus), would be least likely to occur in the area. In fact, one of the science techs with Scripps showed me some interesting data. Normally, he extracts whale calls from hydrophone recordings of the area, from the NEPTUNE project, to hear earthquakes but decided to do the opposite and remove earthquake sounds to listen for whale calls. From that data he has found that blue and fin whale calls in the area occur from October through the winter; which means it was very unlikely there were Endangered blue whales or Threatened fin whales (Balaenoptera physalus) around the MPA during the survey.


Although we had no marine mammal sighting during the survey we did have some sightings of other wildlife; we saw a few more sunfish (Mola mola), on a couple of the calmer days we could see Blue sharks (Prinocae glauca) swimming underwater or at the surface near the ship and a Peregrin Falcon (Peregrinus falco) stayed around the ship for a day. We even saw it attack and kill another bird, which we think was a petrel, and eat it while in flight around the ship!

Above 4 photos: we were lucky to have a juvenile peregrine falcon (Falco peregrinus) join the ship for a day...which made things more interesting for us in the MMO tower!

John and Megan on the old heli-deck. The airgun array can be seen being towed behind the ship.

Above 4 photos: our Peregrine friend caught another bird a ways out from the ship and proceeded to circle us while eating it in flight!

What else is there to say...the beautiful moon

Another beautiful sunset

drifing Bull Kelp (Nereocystic lutkeana)

Above 3 photos: on a rare flat calm day we had a few Blue sharks (Prinocae glauca) swimming at the surface near the ship

During survey time the crew and science techs were also lucky enough to learn more about the research being conducted by the PIs and each of them gave us a talk about their research  (info on Doug Toomey’s research, info on William Wilcock’s research).

From William Wilcock’s website (see link above) this survey was designed to:
“...image the 3-D seismic structure of the crust and topmost mantle along an 80-km-long section of the Endeavour ridge. The experiment will image four targets: (1) crustal thickness variations within 25 km of the axial high (0 to 900 kyr); (2) the 2-D (i.e., map view) structure of the uppermost mantle beneath the spreading axis; (3) the 3-D structure of the crustal magmatic system and (4) the detailed 3-D, shallow crustal thermal structure beneath the Endeavour vent field. The results of imaging will define the recent history of magma supply, the pattern of melt delivery from the mantle to the crust and the structure and segmentation of the subseafloor magmatic and hydrothermal systems.”

AUGUST 22 to 25 RV Langseth MMO cruise: Transit to Endeavour and OBS drops

We left port the morning of August 22 heading down the Columbia River and then out to sea. It took a day to transit to the site during which time we had a sighting of some short-finned pilot whales, (Globicephalus macrorhynchus) which I missed because I wasn’t on watch, and some Pacific White Sided Dolphins (Lagenorhynchus obliquidens).

Above 2 photos: heading to sea down the Columbia River

During our day of transit I helped with some work on the streamer deck, we had an emergency/lifeboat drill, and then the MMOs had an afternoon meeting. Fortunately, I felt pretty good most of the day because I was on deck but during the MMO meeting in the mess I started to feel a little queasy with the smells of the food, looking at computer screens and not seeing the horizon. I was fine during the meeting but when I went down to my cabin, which was small, at the bow and had no porthole, suddenly I was sick! I was lucky though because quite a few of the science crew were already in their bunks with seasickness. After dealing with my first bout of seasickness I made myself go to the mess for dinner and then afterwards, because I was still feeling poor, I sat on deck for a while. Unfortunately, as soon as I went back to my cabin I was sick again! I went to bed at 6:30 and slept through until the next morning.

Releasing the Scripps L-CHEAPO Ocean Bottom Seismometers

Once we arrived on site the Woods Hole and Scripps science crew did release tests on the OBSs (Ocean Bottom Seismometers), which record the seismic data, to ensure that after they were dropped to the seafloor they would later return to the surface when signalled to. After completion of the release tests we spent the next four days dropping the OBSs in various locations around the site. During this time we started our visual rotations and attended the daily meetings with the science crew to discuss and finalize the mitigation measures before the airguns would be turned on. Due to poor sea states, which were mostly between Beaufort 4 and 6, we spent most of this time on the bridge and not on the MMO tower. An exciting sighting for me was a sea spout. I had seen what appeared to be a blow on the horizon but it didn’t look right to be a whale blow; as the ship drew closer and upon better inspection we realized it was a small sea spout! I was quite excited as it was my first seaspout sighting. We got pretty close to it but it dissipated just as it was coming along our port side.

Above 2 photos: Ocean Sunfish (Mola mola) at the study site: Endeavour MPA

August 25 was our last day of OBS deployments and the night before was one of the roughest nights we had during the survey. That morning I woke about every fifteen minutes to the sound of things crashing around the boat. My cabin is at the bow of the boat so every time we went over a big swell I felt the bow drop and my bed come out from under me! Fortunately, the next morning the seas came down quite a bit and we were able to start doing our watches from the MMO tower and we finally had a sighting; one of the MMOs spotted the group of Pacific White Sided dolphins (Lagenorhynchus obliquidens) crossing the bow of the ship. We also saw Ocean Sunfish (Mola mola) which was also an interesting sighting for me as the first and only time I’ve seen Mola was in 2005 when I was helping on a survey off the coast of Spain in the Straits of Gibraltar.

Above 2 photos: The MMO tower with our 'office'