Allison Irwin: Whales! July 16, 2019

NOAA Teacher at Sea

Allison Irwin

NOAA Ship Reuben Lasker

07-25 July 2019


Mission: Coastal Pelagic Species Survey

Geographic Area: Northern Coast of California

Date: July 16, 2019

Weather at 1300 Pacific Standard Time on Monday 15 July 2019

We’re slowly coasting through a dense patch of fog. I can see about 20 meters off the deck before the horizon tapers to a misty, smoky haze. Then my eyes are affronted with a thick wall of white. It’s like we’re inside a room covered in white felt wallpaper – one of those rooms in a funhouse where the walls keep closing in on you as you walk through it.  For safety, the ship keeps sounding a loud horn at least once every 2 minutes to announce our position for other boats in the area. It’s been like this for an hour now. It’s a little spooky.


PERSONAL LOG


On a brighter note, we saw whales earlier this morning! We were one mile off the coast of southern Oregon, and ahead of us we saw the backs of a few whales peeking out of the surface. I was able to grab a pair of binoculars sitting next to me on the bridge, and with those I could clearly see their dark bodies in the water! Every once in a while one would gracefully lift its tail above the surface as it prepared to dive. They were so cute!

Eventually we got closer to them and we started to see more whales on either side of the ship. I spent probably 15 minutes moving from one side of the bridge to the other with my binoculars to get a better look. I’m lucky the NOAA Corps officers are so accommodating! Otherwise I think my constant fluttering from one area to another could’ve been construed as a pain.

The officers like to see whales too, so they were happy to share what they knew with me. It turns out we were most likely watching Humpback Whales. LT Dave Wang, Operations Officer on the ship and trained as an ichthyologist (fish biologist), said most whales have a distinctive blow pattern, tail shape, and dorsal fin size that makes it easier to identify which kind he’s looking at. I had no idea before today that there were so many different species of whales. I knew Orca – Free Willy, Humpback, and maybe something called a Blue Whale? But that would’ve been the extent of it. In the marine mammals identification guide housed on the ship, there are 45 types of whales in the table of contents! And that’s probably not a complete list of all whale species.

At one point today, eventually, once the fog lifted, we were 36 miles off shore and started seeing shoals of coastal pelagic species all around the ship. We could pick them out easily because each shoal looked like a dark, churning, rippled inkspot on the otherwise smooth-as-glass surface. While the low wind conditions are partly what left us in a thick layer of fog all afternoon, it is what also kept the water smooth enough to pick out the shoals. So I guess not all was lost. We saw even more whale activity around these shoals than we saw this morning, and they were a lot closer to the ship! 

One of the whales just off the starboard bow left a footprint. Larger whales like the Humpback produce larger footprints, and the calm sea state today allowed us to see them! It looked like a smooth patch of water in the center of concentric circles.

I’ve been trying to see whales and other marine mammals the whole trip. I saw a sea lion the other day, just one glimpse of it before it went under the water and we left the area, but now having seen the whales I feel pretty content.  The Commanding Officer of the ship also told me that seals or sea lions like to hang out on the pier that we’ll be docking at in San Francisco, so there’s still hope yet!


THE SCIENCE


If you’ve ever been whale watching on a boat, the type of whale you probably saw was a Humpback Whale. They can often be seen near the shore since they like to stay within the continental shelf, and they spend a lot of time near the surface compared to other whales. Not all whale species exhibit this same behavior.  If whales had a personality, I would call the Humpback Whales the Jersey Shore cast of the sea. They do things that come across as attention-seeking behaviors to the outside observer – slapping their unusually long flippers on the surface of the water, smacking their tails against the water in agitation, flipping their tails in the air before diving, and sometimes breaching the surface with their whole bodies. Of course, they’re not doing it to get our attention. But it makes for easy and exciting observation!

All Humpback Whales have unique patterns of coloration and texture on their flukes, so scientists can use photos to track specific animals as they migrate or go about their regular activities in a similar fashion to how we use fingerprints to uniquely identify people.

They also have the advantage of something called countershading. One of the whales I saw today had a silvery-shiny underside to its fluke that glistened in the sunlight and contrasted greatly with the dark, almost black color of its back. A lot of fish and marine mammals like whales and porpoises use countershading to help camouflage them by having naturally darker backs (dorsal side) and lighter stomachs (ventral side). This way when something is looking down at the creature, it blends in with the dark depths of the ocean, and when something is looking up at the creature, it blends in better with the lighter, sunlit layer of water near the surface.

Anything from krill to small fish are fair game for Humpback Whales when they’re hungry. Sometimes a group of Humpback Whales will work together as a team to catch fish. One way they do this is by bubble net feeding. It’s rare to witness, but a bubble net is a pretty sophisticated way to catch fish. It reminds me of the trawling we do each night from NOAA Ship Reuban Lasker except in this case the whales use a circular pattern of bubbles to corral a bunch of fish into one area… then they thrust forward aggressively, quickly, to scoop up the masses. We use a trawl net to corral the little critters into a codend instead of swallowing them whole.

bubble net
Photo of Humpback Whale Using Bubble Net to Catch Anchovies.
Photo by LT Dave Wang, taken earlier this year
krill in a jar
Quart Jar Filled with Krill Collected in a Bongo Tow

Baleen whales, like the Humpback, have a unique mouth that is hard to explain. If you can visualize a pelican’s beak, it looks a bit like that from the outside. These whales gulp a whole mouthful of water – including zooplankton, krill, and small fish – into their mouths, but they don’t swallow it down outright and they don’t exactly chew their food either. With all that saltwater and prey in their mouths, they use long rows of baleen attached to their upper jaw like a fine-toothed comb. And just like we would use a cheesecloth to strain the moisture off of runny yogurt, Humpback Whales filter the water out of their mouths through the baleen and keep the fishy goodness for themselves.


TEACHING CONNECTIONS


Watching the whales all day kept drumming up images in my mind from when I read Grayson by Lynne Cox. I wrote a review of Grayson in July 2014 on the Pennsylvania Council of Teachers of English and Language Arts (PCTELA) blog. This book, by far, is one of my favorite recommendations to read aloud to students.

If you’re not an English teacher, you probably didn’t spend a lot of late nights in college reading novels to cram for a test. It wasn’t part of your major. But you’re missing out! There are so many ways to use novels and literary nonfiction across the content areas.  Grayson, for example, is artfully written. In the book review I wrote it tells Lynne’s “account of meeting a baby whale in the ocean during one of her early morning training swims. This lonely whale, separated from its mother, stays close to Lynne in the water while fishermen search for the mother.  This true yet almost unbelievable story is hauntingly beautiful.”

Taking 15 minutes of class time to read an excerpt from this book aloud could enrich any classroom. There are many instances when she writes about wanting to give up and swim back to shore. The baby whale is ultimately not her responsibility. It was very cold. She’d been out there in the ocean for hours with nothing but her own strength and experience to keep her afloat. She hadn’t eaten all day. But she stayed with the baby whale. She resolved to see it through to the very end. Any teacher can use her stick-with-it attitude as an example to encourage students to work through academic challenges.

One of my friends, blogger Allyn Bacchus, is a middle school social studies teacher. He uses historical fiction in his class every year. He writes, “My 8th grade U.S. History class covers a unit on Industry and Urban Growth in the late 1800’s and early 1900’s.  I have supplemented our unit with the historical fiction novel Uprising written by Margaret Peterson Haddix.  It covers the story of 3 teenage girls and their involvement in the Triangle Shirtwaist Factory in New York in 1911.  The author brings to life the living, working, and social conditions of the time period and allows my students to experience this unit through the eyes of girls who are living in it.”

Through the eyes of girls who are living in it.  This is something a textbook cannot do.

No one knows your discipline, your students, and your intended classroom environment better than you. Take an hour to fall down the Amazon rabbit hole! Search for a topic you find interesting and relevant to your curriculum, read the book review, click on the comparable book recommendations… you get the point.  Most of the time you can find a book preview to check out the text before purchasing – is the font too small? Too complicated? Too boring? Choose a short excerpt from a text you like for your first attempt at using literature in the classroom and build from there.


TEACHING RESOURCES


Since we’re talking about literature today, I’ll narrate the resource list.

  • We can search online for other educators who have already blazed the trail for us. Here is a blog post written by Terry McGlynn titled Assigning Literature in a Science Class.  The post itself is well written, and if you take the time to read through 54 comments below it, you will find lots of other text recommendations for a science classroom.  This article written by Kara Newhouse titled How Reading Novels in Math Class Can Strengthen Student Engagement shows why two math teachers read books in their high school classrooms. One of those teachers, Joel Bezaire, wrote a blog post with suggestions for other novel studies in math class. The other teacher, Sam Shah, shares a student example to explain how powerful it can be to use literature in a math class. It gets students to understand abstract and often elusive mathematical concepts.
  • I’ve written four nonfiction book reviews to accompany this NOAA Teacher at Sea experience and PCTELA is posting one review each week in July to the new media platform on their website. If not Grayson, then maybe you’ll find useful one of the books I read and reviewed to prepare for this trip. They include Gone Tomorrow: The Hidden Life of Garbage, Blind Man’s Bluff: The Untold Story of American Submarine Espionage, The Hidden Life of Trees: What they Feel, How They Communicate – Discoveries from a Secret World, and Biomimicry: Innovation Inspired by Nature.
  • And finally, I would be remiss to end this post without steering you toward The Perfect Storm written by Sebastian Junger about a small fishing vessel and crew caught in an Atlantic storm and In the Heart of the Sea: The Tragedy of the Whaleship Essex by Nathaniel Philbrick – a captivating true story about the whaling industry which is thought to be the inspiration for Moby Dick.

Erica Marlaine: Onboard the City That Never Sleeps, June 28, 2019

NOAA Teacher at Sea

Erica Marlaine

Aboard NOAA Ship Oscar Dyson

June 22 – July 15, 2019


Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Gulf of Alaska

Date: June 28, 2018

Weather Data from the Bridge:

Latitude: 58º 28.54 N
Longitude: 154º 46.05 W
Wind Speed: 16.8 knots
Wind Direction: 190º
Air Temperature:  11º Celsius
Barometric Pressure: 102


Science and Technology Log

Scientists aboard NOAA Ship Oscar Dyson are estimating the numbers and biomass of walleye pollock in the Gulf of Alaska.  They use acoustics (sound data)  to help them do this.

acoustic readout
Acoustic representation of fish in the area


Acoustic representation of fish in an area

Echo sounders send an acoustic signal (ping) into the water.  The sound bounces off objects that have a different density than the surrounding water (such as the swim bladder in a fish) and returns back to the echo sounder.  Using the speed of sound, this technology can determine how deep the fish are in the water column. 

How much sound each object reflects is known as the target strength.  The target strength is dependent upon the type of fish and the size of the fish.  A bigger fish will give off more of an echo than a small fish will.  A fish’s swim bladder is primarily what reflects the sound.  Smelt and krill do not have swim bladders. As a result, they do not reflect as much sound as a pollack would. Even though a big fish gives off more sound energy than a small fish of the same species, it is possible that a return echo could indicate either one big fish or several smaller fish clumped together. A big fish of one species could also give off similar sound energy to a big fish of a different species. For that reason, actual fish are collected several times a day in the nets described in a previous blog.

From a net sample, scientists determine the number of each species in the catch as well as the length and weight of individuals of each species. 

Measuring pollock
Measuring pollock

Additionally, scientists also determine the sex and age of the pollock.  The catch data is used to scale the acoustic data, which in turn allows scientists to estimate how many pollock there are of various size and age groups in a given area. These numbers help scientists  determine the sustainability of the pollock population, which in turn allows the North Pacific Fishery Management Council to set catch quotas. 

Counting krill
Counting krill


Krill Fun Facts:

Krill (aka euphausiids) are small crustaceans (a couple of millimeters long) of the order Euphausiacea.  The word “krill” is a Norwegian word meaning “a small fry of fish.” Krill are found in every ocean and are a major food source. They are eaten by fish, whales, seals, penguins, and squid, to name a few.  In Japan, the Phillipines, and Russia, krill are also eaten by humans.  In Japan, they are called okiami.  In the Phillipines and Russia, they are known as camarones. In the Phillipines, krill are also used to make a salty paste called bagoong. Krill are a major source of protein and omega-3 fatty acids.

krill on spoon
There are many kinds of krill. Thus far, in the Gulf of Alaska, we have been seeing mostly Thysanoessa enermis, which measure approximately 1/2 inch in length.

Personal Log  

People often refer to New York as the city that never sleeps. The same can be said for the NOAA Ship Oscar Dyson. Life onboard the Oscar Dyson carries on 24 hours a day, 7 days a week.  There is never a time that the ship is not bustling with activity.  Everyone on the boat works 12-hour shifts, so someone is always working while others are sleeping (or doing laundry, exercising, or watching a movie in the lounge before they go to sleep.) Most people on the boat work either the noon to midnight shift or the midnight to noon shift.  However, the science team works 4 a.m. to 4 p.m., or 4 p.m. to 4 a.m. I am in the latter group.  It was easier to get accustomed to than I had imagined, although it is sometimes confusing when you look at your clock and wonder whether it is 5 a.m. or 5 p.m. since the sun is shining for most of the day.  Kodiak has only 4-5 hours of darkness now, and the sun sets at approximately midnight.  Therefore, it does not really feel like nighttime for much of my shift.

View
The view from NOAA Ship Oscar Dyson
Sunset
Views (and sunsets) like these make it easy to work the night shift!

Karah Nazor: Sorting Protocol and the Ubiquitous Tunicates of the Central CA Coast: Salps and Pyrosomes, May 30, 2019

NOAA Teacher at Sea

Karah Nazor

Aboard NOAA Ship Reuben Lasker

May 29 – June 7, 2019


Mission: Rockfish Recruitment & Ecosystem Assessment

Geographic Area: Central California Coast

Date: May 30, 2019

Last night I fell asleep, twice, at the lab bench in between trawls, since I am still adjusting to being on the night shift.  We worked from 9:00 P.M. to 6:30 A.M. After the shift I had a nice hot shower and slept a solid 9 hours from 7:00 AM to 4:00 PM.  Hopefully, I will be less drowsy tonight!

Upon waking, I went to the galley and grabbed some Raisin Bran and coffee and took it up to the flying bridge to hang out with Ornithologist Brian Hoover.  Our current location is in the middle of the Channel Islands, an area I know something about because my friend Evan Morrison, mentioned in my first blog, helps with the Channel Islands Swimming Association, and I would like to swim between these islands one day.  Lauren Valentino, Flora Cordoleani, Ily Iglesias and I congregated on the flying bridge and decided we should exercise. We joined Flora in her squat challenge (80 squats on this particular day), followed by 5 minutes of planking and a bit of erging.  Half of female members of the fish sorting team are avid rock climbers. They did lots of pull-ups using the rock ring climbing training holds that are installed there.

It felt nice and warm when the ship stopped for deployment of the Conductivity, Temperature and Depth (CTD) Rosette, and it got chilly again as the wind picked up when the ship started moving again. We saw a few whale spouts in the distance and at 5:30 P.M. we went down to the galley for a delicious meal of steak and mashed potatoes.  I am beginning to really appreciate how nice this whole experience has been in terms of amenities. The NOAA Reuben Lasker first set launch in 2014 and is a state of the art fisheries vessel with a sophisticated acoustics lab, fish lab, dynamic positioning system, CTD, etc., but is ALSO equipped with creature comforts including a movie lounge, an ice cream cooler loaded with ice cream sandwiches, snickers, fruit pops, you name it, and my personal favorite – a coffee bar where all coffee is freshly ground, an espresso machine, and all varieties of milk and creamers, including Reese’s cup whipped cream. The mattress in my stateroom bunk is quite comfortable and the shower gets hot within seconds! I doubt it can get much better than this for a research experience at sea?

Game Plan and Trawling Line: Point Sal line with five 15 minute hauls.

I am familiar with the sorting protocol now. The catch is dropped from the net into the bucket by members of the deck crew and survey tech, with the oversight of Keith Sakuma, Chief Scientist and NOAA Operations Officer Keith Hanson.  The bucket is immediately placed in the fish lab and this is when the fish sorting team starts our work.

Cobb Trawl net
Dropping the catch from the Cobb Trawl net into the bucket.
fish on a sorting tray
A volume of fish just placed on a sorting tray. This catch has a lot of anchovies, krill, and California smoothtongues.
Separating the krill
Separating the krill from the myctophids, Northern anchovies, and California smoothtongues.
Sorting fish group photo
Team Red Hats sorting fish. NOAA’s Keith Hanson in the rear left side.


SORTING AND COUNTING METHOD

We start by carefully picking through a 2000 mL or 5000 mL volume of the harvest, depending on Keith Sakuma’s initial assessment of the species density and volume in the bucket.  The first volume of catch to be sorted is evenly dispersed onto four white sorting trays arrayed on the main lab bench. Once you have a pile of the catch on your tray, you start to separate them into piles of different types of organisms, such as Northern anchovies, ctenophores, krill, salps, pyrosomes, Californian smoothtongues, squid, rockfish, myctophids, and young of year (YOY) fish.  I prefer to use my hands for sorting while others use forceps. Once sorted, we count the number of individuals for each species. If we have difficulty identifying an animal that we have not yet seen, we ask Keith Sakuma or a more experienced team member to help with identification. YOY fish, some in larval form, are particularly difficult for me.

Once sorted and counted, we verbally call out the common name and number of organisms to Keith Sakuma who manually records the data in a 3-ring binder for the lab hard-copy.   For smaller organisms, such as krill or salps, or in hauls with a high number of any particular species, it would be quite tedious to pick out and count each individual in the total haul.  This is why we start with a small subsample volume or 0.5, 2 or 5L, count the individuals in that small volume, establish the ratio for the number of individuals in that volume, and then extrapolate and calculate by the total volume of the haul.  For example, if we counted 97 pyrosomes in the initial 5L sort, and we collected a total of 1000L, then we can say that there are 19,400 pyrosomes in the haul.

Chief Scientist Keith Sakuma
Chief Scientist Keith Sakuma recording the data from a haul during sorting.

Once 20 individuals of each species have been called out, we no longer have to count that species since the ratio for this catch has already been established and to expedite sorting the rest of the volume.  Following sorting, the length of the twenty representatives of each species is measured using electronic calipers and the values populate on an Excel spreadsheet. After measuring, specimens requested by various research institutes including Scripps Institution of Oceanography, Moss Landing, and Monterey Bay Aquarium Research Institute (MBARI) are collected, labelled and frozen.

Flora Cordoleani
Flora Cordoleani keeping track of which specimens are to be preserved for various research groups.
Keith Sakuma bagging specimens to send to collaborators.

Creature(s) feature: Salps and Pyrosomes. 

Salps What are these strange gelatinous organisms in our catch that look like little puddles of clear jelly with a red, green, yellow, and brown digestive organ in the center?  They are goopy, small and slippery making them difficult to pick up by hand. They float on the sea surface and are ubiquitous in our hauls BUT NOBODY KNOWS ABOUT THEM.

These creatures are called salps and belong to the subphylum Tunicata. Tunicates have a notochord in their early stage of life which makes them members of the phylum Chordata, to which humans also belong. Having a transparent body is a way escape being preyed upon.

A group of salps. This species is dime to quarter sized and this number of salps occupies a volume of ~10-15 ml once placed in a beaker.
Salp digestive organs.

Salps are planktonic tunicates  That can be found as individual salps or in long chains called blastozooids.   The salps shown in the photo below were individuals and were notable in most of our hauls. Individual salps in this pile are dime to quarter sized and occupy a volume of ~10-15 ml. We measured the volume of salps in every haul.

While on the topic of salps, I will tell you about a cool 1 inch long salp parasite I found on my sorting tray (see image below). Keith Sakuma explained that it was a deep sea amphipod called Phronima which is a parasitoid that takes up residence inside of a salp’s body, eats the salp’s organs, and then lays its eggs inside of the salp. The King-of-the-salmon, Trachipterus altivelis, (which we are also catching) uses its protrusible jaw to get inside of the salp just to eat this amphipod!

Phronima amphipod
Phronima amphipod – lives and reproduced in salp after eating the salp’s organs. King-of-the-salmon fish use their protrusible jaws to eat the amphipod.
King-of-the-salmon
King-of-the-salmon, Trachipterus altivelis
King-of-the-salmon jaw protruded
King-of-the-salmon, Trachipterus altivelis, who preys upon phronima living inside of salp, with jaw protruded.
A large haul full of salps.

Another type of salp we keep catching is Thetys vagina, a large solitary species of nektonic salp that feeds on plankton, such as diatoms, and is an important carbon sink in the ocean. Thetys has an external surface, or test, that is covered with bumps and ridges, as seen in the photo below.

Thetys vagina, the twin-sailed salp.
Thetys vagina, the twin-sailed salp.
internal filtering organ
The internal filtering organ of Thetys vagina.
Kristin Saksa examining a larger Thetys
Kristin Saksa examining a larger Thetys vagina, or the twin-sailed salp. The dark colored tentacles are downward facing. This is the siphon where water enters the sac-filled body.

Pyrosomes Pyrosoma atlanticum are another type of planktonic tunicate which are very numerous in most of our hauls. Pyrosomes look like bumpy pink hollow tubes with openings on both ends. They are rigid in structure and easy to pick up by hand, whereas salps are goopy and difficult to pick up by hand.  We have collected some pyrosomes that are 13 inches long, while most are in the 4-6 inch range. The small pyrosomes look like clear Tic Tacs, but they do not taste as such.

Pyrosoma atlanticum
Pyrosoma atlanticum, with an ~6 inch specimen on the left and small pyrosomes on the right.

How can pyrosomes be so ubiquitous just 20 miles or so off of the Central California Coast, but I have never seen one that has floated up on the beach or while swimming?

Pyrosoma atlanticum are also planktonic tunicates, but are colonial organisms made up of many zooids held together by a gelatinous structure called the tunic. One end of the tube is wide open and filters the water for zooplankton and phytoplankton, while the other end is tighter and resembles a diaphragm or sphincter. The pyrosomes we harvested appeared in diverse array of pinks and purples.  Pyrosomes are believed to harbor intracellular bioluminescent bacteria. Pyrosomes are drifting organisms that swim by beating cilia lining the branchial basket to propel the animals through the water and create a current for filter feeding. 

Pyrosome rainbow
Pyrosoma atlanticum assorted by color.
Kristin Saksa
Moss Landing Graduate Student Kristin Saksa excited about the large haul of Pyrosoma atlanticum.
high-five
Pyrosoma atlanticum high-five.

Roy Moffitt: Calling in the Drones, August 13, 2018

NOAA Teacher at Sea

Roy Moffitt

Aboard USCGC Healy

August 7 – 25, 2018

 

Mission: Healy 1801 –  Arctic Distributed Biological Observatory

Geographic Area: Arctic Ocean (Bering Sea, Chukchi Sea, Beaufort Sea)

Date: August 13, 2018

 

Current location/conditions: Evening August 13 – northwest of Icy Point Alaska

Air temp 34F, sea depth 45 m , surface sea water temp 42F

 

Calling in the Drones

We have not seen another ship or any other sign of civilization since we left Nome, until today when NOAA scientists coordinated an at sea meeting between the Healy and two saildrones.  Saildrones are remotely piloted sailboats that roam the seas without anyone on board.  A given route is programmed for collecting data and changes to the sailboat’s survey area can be given directly by satellite through the Internet.   After not seeing anything on the horizon for many days when the sail drone came into view it was quite eerie for me.  It was like a random floating traffic cone dropped in the Arctic.  I was amazed that it did not tip over.  The saildrone has a relatively large keel (the fin part of the boat you cannot see under water) to help it from tipping over.  The boat itself is about 7 m long (23 ft)  x 5 m tall ( 16.3 ft) x 2.5 m wide (8.2 ft) with a traveling speed of 3 to 5 knots.

Saildrone on the ocean
The saildrone is a remotely piloted sailboat that contains many scientific instruments.

We collected surface water samples near the drone that will be tested to verify the accuracy of the drones reporting instruments.

The instruments on a saildrone measure weather conditions and ocean conditions and properties.  The ocean data includes measurements for temperature, wave height, sea depth, currents, pH, salinity, oxygen, and carbon dioxide.  Underwater microphones listen for marine mammals and an echosounder can keep track of fish that pass by.   This is a wealth of information in an area of the world where there are so few ships to report back weather and sea observations to civilization.

 

Today’s Wildlife Sightings

We caught Thysanoessa inermis in the big Methot net today. I had to have Nissa Ferm, a fisheries biologist from Lynker Inc working under contract for NOAA, spell that word out for me. She wrote it down without hesitation. I found this amazing because even spell check doesn’t recognize those words.  Nissa identifies many specimens we catch by eye and then verifies identification under a microscope. In general terms, Thysanoessa inermis is a type of organism often referred to as krill and is only about a centimeter in length.

Thysanoessa inermis, a species of krill
Thysanoessa inermis, a species of krill

Thysanoessa inermis is a vital member of the bottom of the food chain and an animal that eats phytoplankton. Phytoplankton is a microscopic plant that lives in the sunlit layers of the ocean and gets energy from the sun.  As with all plants, this is done through the process of photosynthesis. In the case of phytoplankton being an underwater plant, it uses carbon dioxide dissolved in the water in its photosynthesis process. Thysanoessa inermis helps gather this energy in by eating the phytoplankton and then becomes the prey of much larger creatures in the marine food chain such as fish and whales.

 

Now and Looking Forward

Although it was short lived, we saw our first snow flurry today.  It was incredible to see snowflakes in​ August! I am looking forward to more snowflakes and continued cool weather. ​

Pam Schaffer: Sampling the Food- Assessing Krill Populations July 5, 2018

NOAA Teacher at Sea

Pam Schaffer

Aboard NOAA Ship Bell M. Shimada

July 2-10, 2018

Mission: ACCESS Cruise

Geographic Area of Cruise: North Pacific:  Greater Farallones National Marine Sanctuary, Cordell Bank National Marine Sanctuary

 

Weather Data from the Bridge

Date July 5 2018
Time 1100
Latitude 37 30.1’N
Longitude 123 08.5’W
Present Weather/ Sky Cloudy
Visibility (nm) 12
Wind Direction (tree) Light
Wind Speed (kts)  Variable
Atmospheric Pressure (mb) 1021.3
Sea Wave Height (ft) <1
Swell Waves Direction (true) 270°
Swell Waves Height (ft) 1-2
Temperature  Sea Water (C) 13.0°
Temperature Dry bulb (C)

Air Temperature

16.7°
Temperature Wet Bulb (C ) 13.7°

 

Science and Technology Log

Krill are small crustaceans (think shrimp-like) that inhabit the world’s oceans.  They are an essential component of marine ecosystems, residing near the bottom of the food chain.  Krill are a staple in the diet of whales, squid, octopuses and fish.  Understanding the variability of krill populations is an important way of monitoring ocean health.    In order to track the krill population, scientists do two things; they use acoustics to estimate the biomass and use nets to verify the results from the acoustics.

Deploying the Tucker Trawl
Deploying the Tucker Trawl

Scientists use a large net mechanism called a “Tucker Trawl” to collect samples of krill and other zooplankton at various depths in the water column.  A Tucker Trawl is a set of opening and closing cone shaped nets made of fine mesh (holes that are 333 microns in diameter).  The unit we are using has three sections, each with a mouth diameter of 1 meter by 1.5 meters and a sample collector container on the bottom. Krill is collected by dropping the net in a specific location to a specified depth while the ship is slowly moving at a rate of approximately two knots per hour (2.3 mph).  An onboard crane deploys and retrieves the mechanism using a heavy cable. On this cruise we’ve sampled to depths as much as 200 meters deep.   The Tucker Trawl depth and when the nets are opened can be adjusted in order to sample several vertical positions in the water column during a single trawl.

Processing Samples
Processing Samples

Once the samples are back onboard the nets are sprayed down and the collectors are carefully emptied into storage containers for later analysis onshore.  The content analysis will count and identify the various species collected in the sample, as determining sex, size, lifecycle which vary by species.    We’ve observed two different species in our samples; Euphasia pacifica (smallest and most abundant) and Thysanoessa spinifera (larger with a spiny back).  Data collected via these Tucker Trawl sessions is used to construct models for assessing krill biomass using acoustic measuring technology.

 

Thysanoessa spinifera upclose
Thysanoessa spinifera upclose

Loads of Krill
Loads of Krill

Personal Log

Tucker Trawling is wet business but really interesting.   It’s a great learning experience working with Dr. Jaime Jahncke to deploy the nets and process the samples.  We’re doing several trawls each day throughout the cruise- one session around noon and another set around midnight.   I’ve adjusted my sleeping schedule to get a few hours of rest before we start the midnight shift and then I sleep a few hours after we finish working around 4:30 am.  I’m tired but really happy to be here.

 

Did You Know? 

                       

The name “krill” is Norwegian for “small fry of fish”.