SEPTEMBER 11 to 21 RV Langseth MMO cruise: OBS pickup and transit back to Oregon

September 11 was the first day after the seismic guns stopped firing and the crew started to recover the Ocean Bottom Seismometers (OBS); the techs send a signal to the OBSs, which are sitting on the seabed, to release them and they take about 30 minutes to drift up to the surface to be picked up. OBS pickup was done over the rest of the next week and for the rest of the survey we no longer monitored the PAM (Passive Acoustic Monitoring) station so our days were shorter.

The first day after the guns stopped firing just happened to be a perfect, flat calm day and when I came up to the tower to begin my morning visual observation shift the two MMOs on watch before me told me that they had seen a group of Dall’s porpoise (Phocoenoides Dalli) and a Leatherback turtle (Dermochelys coriaceae). I didn’t believe them at first but, sure enough, when I went to do my data entry I saw that the sightings had been entered into the spreadsheet. The principal investigators were lucky that these sightings were the day after the guns were turned off because had they occurred the day before we would’ve had to make them shut the guns down. It was such a gorgeous day with perfect spotting conditions that I decided to come up for more time than just my observation shifts. Later on that day we saw a few more Blue Sharks (Prionace glauca) swimming right at the surface near the ship and another couple of groups of Dall’s porpoise.

 

Above 3 photos: recovering a Woods Hole OBS

Above 3 photos: Dall's porpoise on a flat calm day

Rainbow as seen from the bridge during watch

I was also lucky to celebrate my birthday during this part of the survey. This was my first birthday at sea…and it was a pretty good one thanks to the other crew on board. Many people wished me happy birthday, one of the gunners gave me a nice orange, dark chocolate bar, and one of the Woods Hole techs gave me another chocolate bar. The best part was when I went up to the MMO tower and saw that somebody had decorated it! I found out later that one of the graduate students had gone on the tower after her OBS pickup shift finished at 4 am and decorated the MMO tower while the ship was rolling in the swell in the dark! I had another nice birthday surprise when, although I had wanted a birthday whale, I saw a big male elephant seal (Mirounga angustrirostris) in the water near the ship during one of my watches.

The MMO tower with the birthday decorations...a birthday sign (which you can't see so well because it was blowing in the wind!)

Then, the day after my birthday I got a late birthday present.. a sighting of a new species for me! I was heading up the MMO tower stairs for my morning watch when I spotted a blow off the starboard side of the ship. I saw the blow, which was fairly bushy and not super tall, but not any of the animal’s body. I hollered to John, the MMO going off shift, that there was a whale and he started to make his way back to the tower to check it out too. Unfortunately, when I saw it surface it’s second and last, time he didn’t see it. I saw the back of the animal but not the head and it looked like it had a dorsal fin but it definitely was not a humpback whale (Megaptera novaeangliaea) as I’ve seen many of them and it didn’t look right to be a humpback. After getting over my excitement (yes I was excited!) I described it to the other MMO because I wasn’t too sure what it was. Eventually he told me that it sounded like I saw a sperm whale (Physeter macrocephalus)! I was very excited that I saw my first sperm whale…even though it was only a brief sighting.


We had a few more sightings of porpoise during the last few days of the survey. The weather also picked up just before we headed into port; it wasn’t as bad as the weather we had at the beginning of the survey during the OBS drops; although it was windy (>30 knots) the swell wasn’t as big. Transit day was beautiful and we had some more interesting sightings; 3 fin whales (Balaenoptera physalus), lots of California sea lions (Zalophus californianus), and, another new species for me, a group of Northern Right Whale Dolphins (Lissodelphis borealis). Right whale dolphins are interesting because they don’t have a dorsal fin. Initially I spotted them swimming across our bow and thought they were Dall’s porpoise but they were jumping clear out of the water (which porpoise don't do) so I thought briefly they were Pacific White Sided dolphins (Lagenorhynchus obliquidens) but realised they had no dorsal fin…and that was the defining identifying feature that they were Right whale dolphins!

And some not so nice weather approaching us!

Recovering a Scripps OBS

...and then we had some more rough seas

An older Black-Footed Albatross (Phoebastria nigripes) flying near the ship. Older animals get the lighter feathers around the head and tail.

Nicky and my little cabin...mine was the top bunk. What you see is what we had!

Gary and Ricky working their culinary magic at sea in the mess

The mess

The Pilot boat coming alongside the Langseth to put a pilot to guide us up the Columbia River

One of three fin whales (Balaenoptera physalus) we saw a few miles off the Oregon coast

 The Common Murres (Uria aalge) became more common the closer we got to shore!

California sea lion in flight!

Gull associating with a sunfish (Mola mola)...gulls are known to associate with sunfish by picking parasite, such as copepods, off their skin (reference referring to this association)

Coming back to land was more interesting than I expected; as we drew closer to shore I noticed there were many seabirds we didn’t see offshore (many species of gulls, common murres, and brown pelicans among others), the sea lions, and the smell of land. The smell of the trees and dirt was so distinct! We finished the survey with a beautiful cruise up the Columbia River back to the fishing boats, roads, bridges, houses and shops and restaurants and pubs. As we were pulling into dock we were also treated to a helicopter rescue display by the US Coast Guard for a fishing festival happening that weekend! 

Above 5 photos: Scenery along the Columbia River

Above 3 photos: Brown pelican fishing in the Columbia River

US Coast Guard Helicopter

Above 4 photos: a crowd greets us at the dock...there was a fishereman's festival at the dock and the US Coast Guard were putting on demonstrations just as we were docking

View from my very comfortable hotel room back onshore!

Above 2 photos: my neighbour on a nest outside the hotel room

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.”