By Russell Reardon

It’s hard to believe we’re already steaming for home.  The last two and a half weeks have gone by quickly aboard the Oscar Elton Sette.  In some ways, sea duty is like having two jobs since the ship is now equipped with 24-7 Internet service.  Once the hustle and bustle of the shipboard work is done for the day, it’s time to fire up the laptop and see what awaits via email from the home office.  The excuse of being unreachable while at sea is no longer valid.  At least we don’t have regular telephone service out here….  I digress.  Anyway, for me, the time has passed quickly, with the majority of my waking hours devoted to work both aboard and ashore.

Since you are still reading these mission logs, you must be wondering how this mission went.  So, as we head home, I’ll take a moment to reflect on the various components of the cruise.  These reflections will not be deep thoughts; I aim to keep them on the surface and very brief.  Apologies in advance if I repeat too much background information on the CTDs, Big Eyes and UAS operations already posted on the Mission Homepage or in previous Mission Logs.

CTDs
Excellent weather conditions allowed us to complete our planned transect of CTDs ahead of schedule.  This was welcomed for several reasons.  It opened up additional days to conduct UAS flight ops, and it also allowed us to conduct …wait for it….additional CTDs.  The latter was especially important because the CTD and fluorometer data were indicating that the North Pacific Transition Zone Chlorophyll Front, an important biological feature on the ocean surface and an indicator of surface convergence in the North Pacific, was further north than we had expected.  (La Nina conditions may help account for this.)  As such, we continued to do CTDs as far north as 36°N, or 120 nautical miles further than we expected. (And, remember, we made these casts every 15 nautical miles.) Trusting his data, NMFS Oceanographer Evan Howell did an excellent job of locating the chlorophyll front so that we could continue the mission in the Convergence Zone as planned.  In a previous post, Joe gave an excellent description of what our 12-hr CTD shifts were like.  I’m very glad to have worked the day shift, given the around-the-clock operations!

You probably realize that we didn’t have the luxury of heading straight to coordinates of any particular known patch of marine debris.  Rather, we just had to aim for an area of the North Pacific where marine debris is thought to accumulate this time of year.  We utilized Debris Estimated Likelihood Index (DELI) maps, an experimental product from NOAA CoastWatch, in an effort to direct us to an area of the North Pacific Subtropical Convergence Zone where conditions were conducive to encountering debris aggregations.  These DELI maps were prepared daily from near real-time satellite-derived data on chlorophyll, sea surface temperature, and wind stress.  Results of this mission will actually help ground-truth this satellite data product, as we’ll be able to compare this remotely sensed information with our actual in-water measurements of chlorophyll and sea surface temperature, as well as our debris sightings.  Unfortunately, during this cruise, there were a number of days of gray cloudy skies looming over the Convergence Zone that actually prevented satellite coverage for the DELI map in our very operating area.  Obviously, this wasn’t an ideal situation.  We were largely operating in the blind in terms of the DELIs.  The challenges of fieldwork…

Big Eyes
Our dedicated team of “Big Eyes” observers, lead by Allan Ligon, were perched high above on the ship’s flying bridge during daylight hours for the duration of the cruise, constantly scanning the waters for marine debris and marine mammals.  These folks deserve a lot of credit for sticking to their stations, continually sweeping their high powered binoculars across the ocean surface regardless of the endless rocking and rolling they endured from their positions high on the ship. We encountered a few days of cold, wet, fairly miserable conditions for working anywhere, let alone the flying bridge of the Oscar Elton Sette. 

I don’ t have the official tallies, but it’s safe to say we didn’t encounter as much marine debris as we were expecting, dare I say hoping, to find.  Of course, it’s not that we particularly “wanted” to encounter large amounts of marine debris.  No one wishes that.  But since we know it’s out there, evidenced by the reefs and beaches of the Paphanaumokuakea Marine National Monument and the Main Hawaiian Islands, it would’ve been nice to have detected and removed some of it at sea.

The Observer Team spotted the occasional plastic fragment, fishing buoy, shoe sole, crate, etc., but the two most significant (largest) marine debris sightings were a massive tangle of yellow hawser and a derelict high flier float. We tagged each of these items with a satellite tracker buoy.  Now, by monitoring their positions over time, we hope to learn more about the currents upon which they drift.

The Observer Team also spotted sea turtles, dolphins (including Pacific White-sided Dolphins and Risso's Dolphins), Humpback Whales and Sei/Brydes Whales.

UAS
My primary purpose for being aboard the Oscar Elton Sette was the UAS component of the mission, which is a joint project between the Monument, NOAA Pacific Island Fisheries Science Center’s Coral Reef Ecosystem Division, and Airborne Technologies Inc.  I’ve been representing the Monument on this endeavor sense arriving last June.  I’ve seen the UAS evolve from early test flights last August and December to the airframe it is now.  I’m also one of two official UAS observers aboard, medically cleared by the FAA to watch the thing!  An FAA observer is required to maintain visual contact with the UAS if it operates beyond the line of sight of the pilot.  As it turned out, during each of its flights, the Malolo flew in close proximity to the ship, remaining well within sight of the UAS pilot at all times.  Though my observing duties were not required, I remained member of the team deployed in a small support boat during UAS operations.  We were responsible for retrieving the UAS after it landed in the ocean.

As you know, the UAS component of this mission was really our initial attempt to use UAS technology to aid in the challenge of detecting marine debris in this vast ocean. This mission allowed us to assess the capability of the Malolo and the operation of its various systems for this seaborne application.  Unfortunately, adverse weather limited our total number of flying days to less than we had hoped.  However, with a handful of open ocean flights now under their collective belt, Airborne Technologies Inc. was able to identify a change in the airframe needed to make the UAS a little more rugged for these punishing conditions.  We learned more about its window of safe operations in regards to weather and sea conditions and gained experience with launch and recovery operations from a NOAA ship.  The experience gained in this mission will further the development of both the UAS and operational protocols.

So, that’s a little recap of this cruise.  Even though we aren’t coming home with a 20’ container full of derelict fishing gear plucked from the North Pacific Subtropical Convergence Zone, we are coming home with additional knowledge.  As all the bits and pieces of satellite, oceanographic, and debris sighting data are processed and mapped in the coming days, we’ll learn more about how we may better conduct this type of operation in the future.  We’ll be back…

Thanks for sailing with us.