Tag: Risso’s dolphins

NOAA Teacher at Sea

Mark Van Arsdale

Aboard R/V Tiglax

September 11 – 26, 2018

 

Mission: Long Term Ecological Monitoring

Geographic Area of Cruise: North Gulf of Alaska

Date: September 18, 2018

 

Weather Data from the Bridge

Clear skies, calm seas

59.30 N, 146.15 W (Middleton Island Line)

 

Science Log

Sightings from the Flying Bridge

We finished up night work on the morning of the 17^th in a bit of swell. Our last casts of the Methot and the Bongo nets were bumpy.  It was hard to stand up, and hard to keep objects from shifting dangerously.  But the swell didn’t last, and by time I woke up mid-morning it was a picture-perfect day, clear and calm. The day shift finished up sampling the Kodiak line by dinner, and we began a twenty-four-hour transit from the Kodiak line to Middleton Island east of Prince William Sound. I got the night off, and with it my first solid night of sleep since the trip started.  I felt like a whole new human.

The transit allowed me to spend most of the day in the flying bridge and it was a good day for it.  We sighted fin whales in the morning, numerous sea birds, another Mola mola (ocean sun fish), and two pods of Risso’s dolphins in the afternoon.  The last two sightings are really interesting.  That was the third Mola mola spotted on the trip.   The Mola mola is the largest bony fish in the ocean.  They can grow up to four meters long and three thousand pounds, eating almost exclusively jellies. They are a bizarre looking fish.  They have no true caudal (tail) fin, thin elongated pectoral fins, and a body shaped like more like a giant head than a fish.   They also swim (if you can call it that) on their side.  The interesting thing is that the Mola mola is a sub-tropical fish and should not be seen in the North Gulf of Alaska – but here they are.

The Risso’s dolphins were another unusual sighting.  We saw them in groups of twenty or so.  Fast swimmers and acrobatic in their movements, you could see their characteristically white faces and scratched backs as they jumped out of the water.  None of the crew or scientists on board had ever seen them and we went through three books trying to get a solid ID.  Very little is known about this species, and confirmed sightings at sea are limited.  It’s likely that this will be the farthest north sighting of Risso’s dolphins recorded.

In the last few years, unusual sightings of species have become more common and not just on the surface.  Plankton tows are revealing copepod species more commonly associated with the California Current than the Gulf of Alaska.  It’s possible that these sightings represent observational bias – we are just paying more attention.  But it seems likely that species in the Gulf of Alaska are on the move.

The North Gulf of Alaska changes seasonally, it changes based on your depth and location, and it changes with weather and currents, but it seems obvious that it is also experiencing long term climactic change.  How will that change affect the stability of this rich ecosystem?  How will it affect the large slice of the Alaskan economy that depends on the wealth of fish brought out of the Gulf?  Already this summer, the Gulf of Alaska cod fishery closed due to lack of fish.  A disaster to some of fishermen in Kodiak, and a heavy hit to the Kodiak Island economy. By tomorrow morning we will be at the outflow of the Copper River.  Copper River salmon are famous for their rich flavor, high prices, and dependable arrival, but this summer, fishing for Copper River king and sockeye salmon was also closed for much of the summer. Fish were coming back small or not at all.

Personal Log

Middleton Island

Good weather has left us a bit ahead of schedule, and the captain and chief scientists decided we could make an excursion to Middleton Island.  When I get home I plan to do some more research on the Island, but it seems to have an interesting, albeit short history.  The island is just a few thousand years old, brought up out of the ocean by the tectonic movements of the Pacific and North American plates.  Much of the island is a flat plateau, surrounded by a series of shelves descending down to the water.  Some of the shelves are quite new, the latest edition came during the 1964 Alaska Good Friday Earthquake, as the island was force 12 feet up from the ocean.

The island was once home to a World War II Air Force base.  It was believed that its moderate climate would make an ideal early warning site, but the base was abandoned some time ago. Middleton is currently home to an FAA weather station and an immense number of nesting seabirds.   At some point the disintegrating air force buildings were taken over by those nesting sea birds.  Scott Hatch, a U.S. Fish and Wildlife biologist, saw an opportunity and over the years has turned the old Air Force tower into an observation and study center for nesting black legged kittiwakes.  Over a thousand birds have nests on the outside of the tower, and each one now has a one-way glass window at its back.  The nesting birds can be observed and studied by budding biology students from inside the tower. Studies have been done on their diets, metabolism, behaviors and numerous other details of their private lives. We got to meet Scott and his wife, who were just finishing up some end of the season work on the sight.  They gave us a bit of a tour and showed us where they had built facilities for students and observation sites for nesting common murres, as well as burrow digging sea birds like rhinoceros auklets and puffins. The sea birds were all gone, having fledged their young and returned to the ocean a few weeks before, but it was fun to imagine what the island looked and sounded like with thousands of sea birds on it.

The day off and a shore excursion seemed to leave everyone more relaxed that they have been for the last week.  People smiled and joked and enjoyed the unusually warm September day.  Feeling recharged, I was even looking forward to my night shift.

Cool Moment of the Day

We start working most nights just after the sun goes down.  Last night I noticed there was a bird following us just overhead.  It was an osprey, and it followed us for more than two hours as we worked through the night.  The bird undoubtedly thought we were a fishing vessel and was looking for handouts, but in the middle of the night it was an amusing distraction to look up at the rapture silhouette against the clouds.

Animals seen today

• Fin whales
• Harbor porpoises
• Risso’s dolphins
• Another Mola mola
• Lots of sea birds including puffins, auklets, shearwaters, cormorants, fulmars, petrels, a merlin, an osprey