David Walker: Crossing the Mississippi River Delta (Days 10-12), July 5, 2015

NOAA Teacher at Sea
David Walker
Aboard NOAA Ship Oregon II
June 24 – July 9, 2015

Mission: SEAMAP Bottomfish Survey
Geographical Area of Cruise: Gulf of Mexico
Date: July 5, 2015

Weather Data from the Bridge

Weather Log 7/5/15
NOAA Ship Oregon II Weather Log 7/5/15

This has been some of the smoothest water I’ve seen yet on the ocean.  At times, you can’t even see wave motion on the surface of the ocean, and it looks more like a lake.  On July 5, 2015, waves were estimated to be 1 ft. in height, at most (see above weather log from the bridge).  Sky condition on July 5 began as scattered (SCT, 3-4 oktas), moved to broken (BKN, 5-7 oktas) and overcast (OVC, 8 oktas) by the afternoon and evening, and then returned to FEW (1-2 oktas) by 11 PM.  There was rain observed in the vicinity (VC/RA) at 4 PM, and some lightning (LTG) was observed in the late evening.

Science and Technology Log

The survey is still progressing smoothly.  We have just crossed the Mississippi River delta, and I have observed a much greater human presence in the water — many ships, mostly commercial shrimping vessels, and even more oil rigs than usual.

Of particular interest to me, we have caught many new species over the past couple of days.  One notable new catch on Day 11 was a giant hermit crab (Petrochirus diogenes), the largest species in the Gulf of Mexico.  In most cases, hermit crabs need to be removed from their shells in order to be successfully identified.  This process was much more difficult than I had imagined, and I ended up having to use a hammer to crack the shell.  The crab contained within was indeed large – it amazed me that such a large species could occupy such a moderately-sized shell.  After analyzing the crab in the laboratory, we quickly returned it to the ocean, in the hope that it would find another shell in which to occupy and survive.

Another interesting catch on Day 11 was a seabiscuit (Brissopsis alta).  This organism was caught at a station overlying a sandy/muddy bottom, this type of seafloor environment providing a habitat for these unique creatures.  We were able to prep the seabiscuit with bleach in the same manner in which we prepped the sand dollars a couple of days ago.  The product was a purely white – a very delicate, yet quite beautiful specimen for my classroom.  Much thanks to fisheries biologist Kevin Rademacher for his help in preparing these organisms.

On Days 11 and 12, we caught some particularly large individuals, which made for great photo opportunities.  On Day 11, we caught the largest roundel skate (Raja texana) that we’ve seen yet, and on Day 12, we netted a large gulf smoothhound (Mustelus sinusmexicanus), a shark species that interestingly has no teeth.  The rest of the night shift was encouraging me to take a photo with my hand down the shark’s mouth, but I settled for the typical catch photo.  This shark was swiftly returned to the water (head first) after laboratory analysis was conducted, and it survived the catch.

As we have to open up fish in order to sex them, it is a natural investigative temptation to look at the other anatomy inside the fish.  A usual focal point is the stomach, as many times, fish stomachs are very disproportionately bloated.  Many times, enlargement of organisms such as the air bladder, stomach, and eyes of caught fish is due to barotrauma.  When a fish is quickly taken from deep waters to the surface, the pressure rapidly decreases, causing internal gases to expand.  In certain cases, we have discovered very recently eaten fish inside organisms’ stomachs.  One particularly interesting example was the stomach of a threadtail conger (Uroconger syringinus), in which we found a yellow conger (Rhynchoconger flavus) of equal size!

Uroconger Ate Rhyncoconger
We found the yellow conger on the right inside the stomach of the threadtail conger on the left! Photo credit to Kevin Rademacher.

I have started to realize the very subtle differences between some species.  One great example of such subtle variance is found in two similar sole species – the fringed sole (Gymnachirus texae) and the naked sole (Gymnachirus melas).  The naked sole contains a faint secondary stripe in between each of the bold stripes on its back; the fringed sole does not have this stripe.  During our initial sorting of species, I unwittingly threw both of these species into the same basket.  Fortunately, fisheries biologist Kevin Rademacher noticed what I was doing and identified the distinguishing phenotypic difference.  I have adjusted the brightness, contrast, and shadowing of the below photos to make the difference in striping more apparent.

Flatfish, such as the soles above, have a very interesting developmental pattern from juvenile to adult.  Fisheries biologists Kevin Rademacher and Alonzo Hamilton were able to nicely summarize it for me.  As juveniles, they start off with eyes on both sides of their heads and swim in the same manner as normal fish.  However, once they get large enough to swim out of the current, they “settle out” onto the seafloor.  At this time, a very interesting series of morphological changes takes place.  Notably, the eyes of the fish migrate such that they are both on one side of the fish’s body.  This morphological change has clearly been evolutionary favored over generations, as it allows the fish to see with both of its eyes while slithering along the seafloor.  The side of the fish on which the eyes end up depends on the particular species of fish.  Flatfish are accordingly categorically defined as “right-eyed” or “left-eyed,” based on the side of the fish containing the eyes.  The procedure is fairly simple to define a flatfish a right-eyed or left-eyed.

  1. Look down at the side of the fish containing both of the eyes.
  2. Orient the fish such that the eye that migrated from the opposite side is on top.
  3. If the head faces left, the flatfish is defined as left-eyed.
  4. Otherwise, it is defined as right-eyed.

On many occasions, we have been able to keep some of our catch to later eat.  I have had fresh white shrimp, brown shrimp, red snapper, lane snapper, vermillion snapper, hogfish, and even paper scallops.  I have obtained lots of practice heading shrimp and fileting fish, as well as shucking scallops.  It has been very interesting to visualize the entire process, from catch to table.  It is true what they say, incredibly fresh seafood tastes much better.  Most of the credit here goes to Chief Steward (CS) Mike Sapien and Second Cook (2C) Lydell Reed, the chefs on the ship.

Also after my shift, I was able to visit the ship’s bridge for the first time during the day.  The environment at night is quite different on the bridge, as the NOAA Corps Officers driving the ship need to keep their eyes adjusted to the dark.  Accordingly, the only lights used in the bridge at night are red, reminding me of the lights used by the scientists I observed on a recent night trip to the UT McDonald Observatory.  My trip to the bridge during the day allowed me to observe the operation of the ship and many instruments clearly for the first time.  It was honestly quite intimidating — so many instruments, controls, and dials, and I had no clue what any of them did.  I was very scared to touch anything – the only instrument with which I braved to interact was a very nice pair of binoculars.  The ship is always driven by NOAA Corps Commissioned Officers.  During the time of my observation, Ensign (ENS) Laura Dwyer, a Junior Officer, and Lieutenant Junior Grade (LTRG) Larry Thomas, the ship’s Operations Officer, were on the bridge.  The Captain (Commanding Officer) of the ship, Master David Nelson, entered and exited periodically.  ENS Dwyer was very kind to point out to me different instruments on the bridge and discuss the operating of the ship.  Interestingly, the NOAA Ship Oregon II operates on a system similar to that of a car with a manual transmission – while the ship has two engines instead of one, each engine has a clutch.  There is also a controllable pitch system that allows the operator of the ship to change the angle of the propeller.  There are two RADAR devices, as well multiple GPS navigational systems, on which the stations of the survey are plotted.  The are multiples of each of these important ship systems as a safety measure.  Despite the GPS systems, the ship still has a chart table on the bridge, and even a chart room, where routes are plotted out in more detail.  The helm, which controls the rudder, is still a large, prominent wheel, just as it was in the pirate stories I read as a child.  ENS Dwyer told me, however, that helms are much more abbreviated in appearance in more modern ships.  She indicated that many members of the NOAA Corps appreciate the “vintage” feel of the bridge of the NOAA Ship Oregon II — the ship will be 50 years old in 2017!

We have more or less finished the intended stations for Leg 2 of this survey, but as we still have time left before we are due back in port, we have received orders to proceed through to Leg 3 stations.  These stations are entirely across the Gulf of Mexico, along the western coast of Florida.  The traveling time there is over 14 hours by boat, and we will be traveling more or less as the crow flies.  I am really looking forward to these new stations, as I have heard the biodiversity is vastly different.

Survey Locations
Sections of the 2015 SEAMAP Bottomfish Survey

Personal Log

Ever since my shift on Day 11, in which I felt particularly fatigued and engorged, I have been completing cardio workouts daily.  There is quite a bit of workout equipment stored in various places throughout the ship, and I have finally found an enjoyable cardio workout.  I am using a rowing machine that I found on the top deck of the ship, and I set it up to face the direction of the ship’s movement.  In this way, when I row, I feel as though I am actually pushing the boat through the water.  The wave motion and periodic jostling of the ship makes the rowing machine feel even more like the real thing, and I am forced to recall my days rowing at the crack of dawn on Lake Dunmore near Middlebury, Vermont while in college.

Workout Setup
My workout setup on the top deck of the ship

The Fourth of July on the boat was free of any special pomp and circumstance.  It was, more than anything, just another work day.  Fortunately, all of the employees on the boat get paid overtime for working this day, as well as weekend days.  I definitely missed the Zilker fireworks celebration in Austin (TX), but it was meaningful to be on a boat with members of the NOAA Corps, a Commissioned Service of the United States, on this important day for America.

I have made significant progress in Tender is the Night and am almost finished.  I have also spent free time watching the FIFA Women’s World Cup and the Wimbledon Championships on the satellite television upstairs.

Regarding my sleep, I have finally stopped taking Dramamine®.  Lo and behold, I have had no more nightmares, this lending further support to my theory that Dramamine® was the cause.

The days are still very exciting, and I have yet to encounter a day without a great deal of fresh learning.  On to Florida!

Did You Know?

The Navy Motion Picture Service provides encrypted DVDs for use on deployed ships.  In the upstairs lounge, there are well over 700 DVDs, from classics to quite new releases, organized for anyone to watch in their free time.

DVD Binder
On of the many DVD binders on the ship, courtesy of the Navy Motion Picture Service

Notable Species Seen


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