Johanna Mendillo: Time to Bid Alaska, the Bering Sea, and the Oscar Dyson Adieu… August 9, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA Ship Oscar Dyson
July 23 – August 10

Mission: Pollock research cruise
Geographical area of the cruise: Bering Sea
Date: Thursday, August 9, 2012

Location Data from the Bridge:

Latitude: 57 28 ’ N
Longitude: 173 54’W
Ship speed: 11.2 knots ( 12.9 mph)

Weather Data from the Bridge:

Air temperature: 8.0 C (46.4 ºF)
Surface water temperature: 8.3 C (46.9ºF)
Wind speed: 7.4 knots ( 8.5 mph)
Wind direction: 130T
Barometric pressure: 1015  millibar (1 atm)

Science and Technology Log:

We have now completed 44 hauls in our survey and are on our way back to Dutch Harbor!  You can see a great map of our sampling area in the Bering Sea– click below.

Map showing sampling transects for Leg 3 of Summer 2012 NOAA Pollock Cruise

From those hauls, let me fill you in on some of the cool statistics:

  • We caught approximately 118,474 pollock and they weighed 24,979.92 kg (= 25 tons)!


  • Last year’s official total allowable catch (called a quota) for all commercial fishermen in Alaska was 1.17 million tons!

So, we only caught 25 tons/ 1,170,000 tons = 0.00002 = 0.002% of the yearly catch in our study.


  • The estimated population of pollock in the Bering Sea  is 10 million tons (10,000,000 T)!
  • This means we caught only 0.00025% of the entire pollock population!

So, as you can see, students, in the big picture, our sampling for scientific analysis is quite TINY!

Continuing with more cool pollock data…

  • We identified 7,276 males and 7,145 females (and 2,219 were left unsexed)
  • We measured 16,640 pollock lengths on the Ichthystick!
  • Pollock lengths ranged from 9cm to 74cm
  • We measured 260 lengths of non-pollock species (mostly jellyfish, pacific herring, and pacific cod)
  • We collected 1,029 otoliths for analysis

You will hear more about our results this fall— as well as the management decisions that will be made with this valuable data…

We have also had some exciting specimens on our bottom trawls.  Remember, students, this simply means we drag the 83-112 net along the ocean floor.  By sampling the bottom, we collect many non-pollock species that we would never see in the mid-water column.

Preparing what looks to be a LARGE catch from the bottom trawl...
Preparing to open what looks to be a LARGE catch from the bottom trawl…

Here are some of my favorites:

This was a large Pacific Cod...
This was a large Pacific Cod…
Our close-up!
Our close-up!

Next up, a very different sort: the Opilio Tanner Crab and the Bairdi Tanner Crab- both are known in the market as Snow Crabs!

Snow crabs, big and small
Snow crabs, big and small

Perhaps my favorite…

The one and only... spiny lumpsucker!
The one and only… Siberian lumpsucker!  Yes, this specimen is full grown and no, we did not eat her, don’t worry!

Followed by a slightly different type of lumpsucker!

Contrast that with the regular lumpsucker!
Contrast that with a full grown adult smooth lumpsucker!  So ugly it is cute…

These types of nets require a lot of hands to help sort the species as they come down the conveyor belt!

Hurry up and sort!
Hurry up and sort!
Oh yes, there is MORE sorting to be done!
Oh yes, there is MORE sorting to be done!

Onto… sea urchins!

Sea Urchins!
Beautiful sea urchins!
Here is fellow TAS (Teacher at Sea) Allan removing a grouper...
Here is fellow TAS (Teacher at Sea) Allan removing a … sculpin!

And lastly, to those specimens you may have been waiting for if you are a fan of the “Deadliest Catch” TV show…

It wouldn't be a proper trip to the Bering Sea without Alaskan king crabs, right?
It wouldn’t be a proper trip to the Bering Sea without Alaskan king crabs, right?

Interested in playing some online games from NOAA, students?  Then visit the AFSC Activities Page here— I recommend “Age a Fish” and “Fish IQ Quiz” to get your started!

Lastly, students, as one final challenge, I would like you to take a look at the picture below and write back to me telling me a) what instrument/tool he is using and b) what it is used for:

Here is Rick... hard at work!
Here is Rick… hard at work!

Personal Log:

Well, my time at sea has just about come to an end.  This has been a wonderful experience, and I am very grateful to the NOAA science team (Taina, Darin, Kresimir, Rick, Anatoli, Kathy, and Dennis) for teaching me so much over these last three weeks.  They have wonderful enthusiasm for their work and great dedication to doing great science!  Not only do they work oh-so-very-hard, they are a really fun and personable group to be around!  Many, many thanks to you all.

Thanks also go to my Teacher at Sea partner, Allan Phipps, for taking photos of me, brainstorming blog topics, helping out processing pollock during my shift, and other general good times.  It was great to have another teacher on board to bounce ideas off of, and I learned a great deal about teaching in Southern Florida when we discussed our respective districts and schools.

I would also like to thank the NOAA officers and crew aboard the Oscar Dyson.  I have really enjoyed learning about your roles on the ship over meals and snacks, as well as many chats on the bridge, deck, fish lab, lounge, and more.  You are a very impressive and efficient group, with many fascinating stories to tell!  I will look forward to monitoring the Dyson’s travels from Boston online, along with my students.

Goodbye Oscar Dyson!
Goodbye Oscar Dyson! (Photo Credit: NOAA)

In the upcoming school year, students, you will learn how you can have a career working for NOAA,  but you can start by reading about it here:

  • NOAA (the National Oceanic and Atmospheric Administration)
  • NOAA Corps (the NOAA Commissioned Officer Corps)
  • Alaskan Fisheries Science Center (the research branch of NOAA’s National Marine Fisheries Service dedicated to studying the North Pacific Ocean and East Bering Sea)
  • MACE (the Midwater Assessment and Conservation Engineering program- the NOAA group of scientists I worked with- based in Seattle)

Special thanks to our Commanding Officer (CO) Mark Boland and Chief Scientist Taina Honkalehto for supporting the Teacher at Sea program.  I know I speak on behalf of many teachers when I say there are many, many ways I will be bringing your work into the classroom, and I hope, helping recruit some of the next generation of NOAA officers and scientists!

There are many pictures I could leave you with, but I decided to only choose two- one of a lovely afternoon on deck in the Bering Sea, and the other, of course, one more of me with a pollock head!

A lovely afternoon on the Bering Sea...
A lovely afternoon on the Bering Sea…

Last, but not least….

Thank you very much NOAA and the Teacher at Sea program!
Thank you very much NOAA and the Teacher at Sea program!

Johanna Mendillo: Hello pollock…. can you hear me now? August 7, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA ship Oscar Dyson
 July 23 – August 10

Mission: Pollock research cruise
Geographical area of the cruise: Bering Sea
Date: Tuesday, August 7, 2012

Location Data from the Bridge:
Latitude: 59 52 ’ N
Longitude: 177 17’ W
Ship speed:   8.0 knots ( 9.2 mph)

Weather Data from the Bridge:
Air temperature: 7.3C (45.1ºF)
Surface water temperature: 8.4C (47.1ºF)
Wind speed:  4 knots ( 4.6 mph)
Wind direction: 75T
Barometric pressure:  1018 millibar (1 atm)

Science and Technology Log:

We are wrapping up our final few sampling transects.  Now that you are practically fisheries biologists yourselves from reading this blog, students, we must return to the fundamental question— how do we FIND the pollock out here in the vast Bering Sea?  The answer, in one word, is through ACOUSTICS!

Look at all of these birds off the stern!  Why do you think they are following us?  Are we about to haul up a catch, perhaps?
Look at all of these birds off the stern! Why do you think they are following us? Are we about to haul up a catch, perhaps?

Hydroacoustics is the study of and application of sound in water.  Scientists on the Oscar Dyson use hydroacoustics to detect, assess, and monitor pollock populations in the Bering Sea.

Now, you may have heard of SONAR before and wonder how it connects to the field of hydroacoustics.  Well, SONAR (SOund Navigation and Ranging) is an acoustic technique in which scientists send out sound waves and measure the “echo characteristics” of targets in the water when the sound waves bounce back— in this case, the targets are, of course, the pollock!  It was originally developed in WWI to help locate enemy submarines!  It has been used for scientific research for over 60 years.

(PLEASE NOTE: The words sonar, fishfinders, and echosounders can all be used interchangeably.)

The transducer sends out a signal and waits for the return echo...
The transducer sends out a signal and waits for the return echo once it bounces off the fish’s swim bladder… (Source:

On the Dyson, there is, not one, but a collection of five transducers on our echosounder, and they are set at five different frequencies.  It is lowered beneath the ship’s hull on a retractable centerboard.  The transducers are the actual part of the echosounder that act like antennae, both transmitting and receiving return signals.

The transducers transmit (send out) a “pulse” down through the water, at five different speeds ranging from 18-200kHz, which equals 18,000-200,000 sound waves a second!

When the pulse strikes the swim bladders inside the pollock, it gets reflected (bounced back) to the transducer and translated into an image.

First of all, what is a swim bladder?  It is simply an organ in fish that helps them stay buoyant, and, in some cases, is important for their hearing.

Swim Bladder (Source:
Swim Bladder (Source:

Now, why do the pulses bounce off the swim bladders, you ask?  Well, they are filled mostly with air and thus act as a great medium for the sound waves to register and bounce back.

Think of it this way: water and air are two very different types of materials, and they have very different densities.  The speed of sound always depends on the material through which the sound waves are traveling through.  Because water and air have very different densities, there is a significant difference in the speed of sound through each material, and that difference in speed is what is easy for the sonar to pick up as a signal!

It is the same idea when sound waves are used to hit the bottom of the ocean to measure its depth- it is easy to read that signal because the change in material, from water to solid ground, produces a large change in the speed of the sound waves!

Here is a sonar system measuring the depth of the ocean...
Here is a sonar system measuring the depth of the ocean… (Source:

Interestingly, different types of fish have different shaped and sized swim bladders, and scientists have learned that they give off different return echos from sonar signals!  These show up as slightly different shapes on the computer screen, and are called a fish’s “echo signature”.  We know, however, that we will not encounter many fish other than pollock in this area of the Bering Sea, so we do not spend significant time studying the echo signatures on this cruise.

So, what happens when these signals return to the Dyson?  They are then processed and transmitted onto the computer screens in the hydroacoutsics lab on board.  This place is affectionately known as “the cave” because it has no windows, and it is, in fact, the place where I spend the majority of my time when I am not processing fish!  Here it is:

Here is Anatoli observing potential fish for us to go catch!
Here is Anatoli observing potential fish for us to go catch!

We spend a lot of time monitoring those computer screens, and when we see lots of “specks” on the screen, we know we have encountered large numbers of pollock!

Here we are approaching a LARGE group of pollock!
Here we are approaching a LARGE group of pollock!

When the scientists have discussed and confirmed the presence of pollock, they then call up to the Bridge and announce we are “ready to go fishing” at a certain location and a certain depth range!  Then, the scientists will head upstairs to the Bridge to work with the officers and deck crew to supervise the release, trawling, and retrieval of the net.

Now, in addition to the SONAR under the ship, there are sensors attached to the top of the net itself, transmitting back data.  All of the return echos get transmitted to different screens on the bridge, so not only can you watch the fish in the water before they are caught, you can also “see” them on a different screen when they are in the net!  As I told you in the last post, we will trawl for anywhere from 5-60 minutes, depending on how many fish are in the area!

Left: Echosounder at work/  Right: The "return signature" is visible on the computer!
Left: Echosounder at work/ Right: The “return signature” is visible on the computer!  (Source:
A full catch- success!  Without acoustics, it would be much harder for NOAA to monitor and study fish populations.
A full catch- success! Without acoustics, it would be much harder for NOAA to monitor and study fish populations.

Personal Log:

In these last few days, we have crossed back and forth from the Russian Exclusive Economic Zone (EEZ) and the U.S. several times.  There were some nice views of Eastern Russia before the clouds and fog rolled in!

I can see Russia from my ship!
I can see Russia from my ship! (Photo Credit: Allan Phipps)

In addition, we crossed over the International Date Line!  It turns out that everyone on board gets a special certificate called the “Domain of the Golden Dragon” to mark this event.  This is just one of a set of unofficial certificates that began with the U.S. Navy!  If you spend enough time at sea, you can amass quite a collection- there are also certificates for crossing the Equator, Antarctic Circle, Arctic Circle, transiting the Panama Canal, going around the world, and more…

I will award a prize to the first person who writes back to tell me what does it mean when one goes from a “pollywog” to a “shellback”, in Navy-speak!

Here is a picture of me with the largest pollock I have seen so far- 70cm!

If I am 5' 4", how many 70cm pollock would it take to equal my height?
If I am 5′ 4″, how many 70cm pollock would it take to equal my height?

Lastly, on to some, perhaps, cuter and more cuddly creatures than pollock- pets!  Here in the hydroacoustics lab, there is a wall dedicated to pictures of pets owned by the officers, crew, and scientists:

Those are some pretty cute pets left ashore...
Those are some pretty cute pets left ashore…

Clearly, this is a dog crowd!   I did learn, however, that our Chief Scientist, Taina, has her cat (Luna) up there!  Students, do you remember the name of my cat and, what do you think, should I leave a picture of her up here at sea?

Johanna Mendillo: Nets, Northern Sea Nettles and More…, August 5, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA ship Oscar Dyson
July 23 – August 10

Mission: Pollock research cruise
Geographical area of the cruise: Bering Sea
Date: Sunday, August 5, 2012

Location Data
Latitude: 61º 10′ N
Longitude: 179º 28’W
Ship speed: 4.3 knots ( 4.9 mph)

Weather Data from the Bridge
Air temperature:  11.1ºC (52ºF)
Surface water temperature: 8.1ºC (46.6ºF)
Wind speed: 5.4 knots ( 6.2 mph)
Wind direction: 270ºT
Barometric pressure: 1013 millibar ( 1.0 atm)

Science and Technology Log:

So far, you have learned a lot about the pollock research we conduct on board.  You have learned:

  • How to age fish (with otoliths)
  • How to measure fish (with the Ichthystick)


  • How to identify fish gender (with your eyes!)

Now, we are going to backtrack a bit to the two big-picture topics that remain:

  • How do we CATCH the pollock (hint hint, that is today’s topics… NETS!)


  • How do we even find pollock in the Bering Sea (that is the next blog’s focus: acoustics!)

So, to begin, there are several types of nets we are carrying on board.  Remember, when a net is dragged behind a ship in the water it is called trawling, and the net can be considered a trawl.  The most-used is the Aleutian Wing Trawl, or AWT, which we use to sample the mid-water column (called a midwater trawl).  We are also using a net called the 83-112, which is designed to be dragged along the ocean floor as a bottom trawl, but we are testing it for midwater fishing instead.  In fact, sometimes during my shift we do one AWT trawl, and immediately turn around and go over the same area again with the 83-112 to see differences in the fish sizes we catch!

If the 83-112, which is a smaller net, proves to be adequate for midwater sampling, NOAA hopes it can be used off of smaller vessels for more frequent sampling, especially in the years the NOAA does not conduct the AWT (NOAA currently does AWT surveys biennially).

Now, for each type of net, there is some new vocabulary you should know:

 A typical midwater trawl
A typical midwater trawl…

The codend is the bottom of the net.  A closed codend keeps the fish inside the net and an open cod end allows them to swim through.  It may seem odd, but yes, sometimes scientists do keep the codend open on purpose!  They do this with a camera attached to the net, and they simply record the numbers of fish traveling through a certain area in a certain time period, without actually collecting them!  Here on the Dyson, the NOAA team is testing that exact type of technology with a new underwater camera called the Cam-Trawl, and you will learn about it in a later post.

The headrope is the top of the opening of the net.

The footrope is the bottom of the opening of the net.

(The 83-112 is called such because it has an 83 ft headrope and an 112 ft footrope.)

The trawl doors are in front of the headrope and help keep the net open.  Water pressure against the trawl doors pushes them apart in the water column during both setting of the net and while trawling, and this helps spread out the net so it maintains a wide mouth opening to catch fish.

There are floats on the top of the net and there can be weights on the bottom of the net to also help keep it open.

Lastly, the mesh size of the net changes: the size at the mouth of the net is 3 meters (128in.), and it decreases to 64in., 32in., 16in.., 8in., etc. until it is only ½ inch by the time you are holding the codend!

Here is a diagram to put it all together:

Courtesy of Kresimir Williams, NOAA

If you think about the opening of the net in terms of school buses, it will help!  It turns out that the AWT’s opening height, from footrope to headrope, is 25m, which is 2 school buses high!  The AWT’s opening width, is 40m across, about 3.5 school buses across!  Now, you can see why positioning and maneuvering the net takes so much care– and how we can catch a  lot of pollock!

Here is a trawl returning back to the ship's deck!
Here is a trawl returning back to the ship’s deck!

Now, when the scientists decide it is “time to go fishing” (from acoustic data, which will be the topic of the next blog) they call the officers up on the Bridge, who orient the ship into its optimal position and slow it down for the upcoming trawl.  Meanwhile, the deck crew is preparing the net.  The scientists then move from their lab up to the Bridge to join the officers– and they work together to monitor the location and size of the nearby pollock population and oversee the release and retrieval of the net.

Along the headrope, there are sensors to relay information to the Bridge, such as:

  • The depth of the net
  • The shape of the net
  • If the net is tangled or not
  • How far the net is off the bottom and
  • If fish are actually swimming into the net!

The fish and the net are tracked on this array of computer screens.  As the officers and scientists view them, adjustments to the net and its depth can be made:

The Bridge!
The Bridge!

The start of the trawl is called “EQ” – Equilibrium and the end of the trawl is called “HB” – haul back.  The net can be in the water anywhere from 5-60 minutes, depending on how many fish are in the area.

The AWT will get would up on this new reel
The AWT will get wound up on this reel

Now, sometimes an AWT catches so many fish that there are simply too many for us to measure and process in a timely fashion, so it is deemed a “splitter”!  In a splitter, there’s an extra step between hauling in the net from the ocean and emptying it to be sorted and processed.  The codend of the AWT is opened over a splitting crate, and half of the pollock go into a new net (that we will keep and sort through) and the rest of the pollock are returned to the water.

 The net is back on board!  Time to open up the codend and see what we have caught!
The net is back on board! Time to open up the codend and see what we have caught!

Personal Log:

Let’s continue our tour aboard the Oscar Dyson!  Follow me, back to the bridge, where the OOD (Officer on Duty) is at the helm.  As you already know, the first thing you notice on the bridge is the vast collection of computer screens at their disposal, ready to track information of all kinds.  You will learn more about these in an upcoming blog.

Busy at work on the bridge...
Busy at work on the Bridge…

In addition to these high-tech instruments, I was very happy to see good old-fashioned plotting on a nautical chart.  In class, students, you will have a special project where you get to track the changing position of the Oscar Dyson!

This chart is showing the northernmost point of three of our sampling transects- including the one closest to Russia!
This chart is showing the northernmost point of three of our sampling transects- including the one closest to Russia!

Here is a sample of the hour-by-hour plotting, done by divider, triangle, and pencil:

Can you spot them, hour by hour?
Can you spot them, hour by hour?

I will end here with a sea specimen VERY different from pollock, but always a fan favorite— jellyfish!  Interestingly, there are a large number of jellyfish in the Bering Sea- something I never would have assumed.  The one that we catch in almost every net is the Northern Sea Nettle (Chrysaora melanaster).  In one net, we collected 22 individuals!

When we collect non-pollock species such as these, we count, weigh, and record them in the computerized database and then release them back into the ocean.  Here they are coming down the conveyor belt after the net has been emptied:

Processing a net with many a jelly!
Processing a net with many a jelly!

The so-called bell, or the medusa, can be quite large- some are the diameter of large dinner plates (45cm)!  Their tentacles can extend to over 3m in length.  They consume mostly zooplankton, small fish (including juvenile pollock), and other jellies.  How so, exactly?  Well, when the tentacles touch prey, the nematocysts (stinging cells) paralyze it.  From there, the prey is moved to the mouth-arms and finally to the mouth, where it’s digested.

Some of the larger ones!
Some of the larger ones!

This same mechanism is used by sea nettle when it encounters danger like a large predator.  It stings the predator with its nematocysts and injects its toxins into its flesh.  In the case of smaller predators, this venom is strong enough to cause death.  In larger animals, however, it usually produces a paralyzing effect, which gives the sea nettle enough time to escape.

Now in the case of me handling them… and other humans…their sting is considered moderate to severe.  In most cases, it produces a rash, and in some cases, an allergic reaction.  However, we wear gloves on board and none of the scientists have ever had an issue holding them.  In fact, they offered to put one on my head and take a picture… but I declined!  If a few students email me, begging for such a picture, maybe I will oblige…

Johanna Mendillo: How Well Do You Know Your Pollock? August 4, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA Ship Oscar Dyson
July 23 – August 10, 2012

Mission: Pollock Survey
Geographical area of the cruise: Bering Sea
Date: Saturday, August 4, 2012

Location Data from the Bridge:
Latitude: 62  20’ N
Longitude: 179 38’ W
Ship speed:  0.8 knots (0.9 mph)

Weather Data from the Bridge:
Air temperature: 7.1C (44.8ºF)
Surface water temperature: 8.3C (46.9ºF)
Wind speed: 22.7 knots (26.1 mph)
Wind direction: 205T
Barometric pressure:  1009 millibar (1.0 atm)

Science and Technology Log:

Out of the 30,000+ species of fish on earth, I would now like to introduce you to the fish we follow morning, noon, and night: pollock.

It is time for some fish biology 101!  The scientific name for pollock, also called walleye pollock, is Theragra chalcogramma.  This is a different species from its East Coast relative,  Atlantic Pollock.  They are in the same family as cod and haddock.

Juvenile pollock
Juvenile pollock… aren’t they cute?

AGE & SIZE:  Pollock are a fast-growing species that typically live to approximately 12yrs, but some live longer.  They are torpedo shaped (long, narrow, and with a streamlined body) and have speckled coloring that help them camouflage with the seafloor to avoid predators.  They generally range from 10-60cm in size; we have been collecting pollock generally in the 20-40cm range so far on this cruise.  Here I am holding one of the larger specimens I have seen so far:

One of the larger pollock I have seen so far...
One of the larger pollock I have seen so far…41cm!

WHERE THEY LIVE:  Younger pollock live in the mid-water region of the ocean; older pollock (age 5 and up) typically dwell near the ocean floor.  In order to sample both of these groups, we conduct trawls throughout the water column so we can get representative biological information from all habitats.

Here I am weighing pollock...
Here I am weighing pollock…


Juvenile pollock eat a type of zooplankton called euphausids, otherwise known as krill, copepods, and small fish.  Older pollock feed on other fish…. including juvenile pollock, making them a cannibalistic species!  Pollock play an integral role in the Bering Sea food web and you will help construct that web back at school!

REPRODUCTION:  Pollock are able to reproduce by the age of 3 or 4.  In our work, we have to determine the sex of each fish by slicing it open because no reproductive organs are visible on the outside!  So, in addition to seeing the insides of many, many fish heads, I have now seen many, many fish gonads.  Here is a poster we use in the lab to learn how to identify the ovaries and testes at five different developmental stages (immature, developing, pre-spawning, spawning, and spent).

Poster showing male and female reproductive organs for ages 1-5
Poster showing ovary and testes stages 1-5!
And... it is a female!
And… it is a female!

So, how do you tell, exactly?  On the females, we go by the following guidelines:

Immature female pollock contain small ovaries tucked inside the body cavity, the ovary looks transparent, and there are no eggs visible.

Developing females have more visible and pink-ish ovaries, generally transparent to opaque.

Pre-spawning females contain large bright orange ovaries and eggs are easily discernible inside them

Spawning females have large ovaries bursting with hydrated eggs  (the fish has absorbed large amounts of water at this point), so the eggs look translucent or even transparent!

Spent females have empty flaccid ovaries.

It can sometimes be difficult to identify a female maturity stage by this simple visual scale (this is called macroscopic inspection), due to subjective interpretations of color, ovary size, and visibility of eggs, so fisheries biologists can also collect cell samples to look at gamete stages under the microscope (this is called histological analysis).  For example, a female’s ovaries can be slightly different colors based on her diet.  We are not collecting those types of samples on this cruise, however, but those are often collected during wintertime pollock cruises in the Gulf of Alaska.

These are ovaries in the pre-spawning stage
These are ovaries in the pre-spawning stage     (Photo Credit: Story Miller, TAS 2010)

Regardless of the method used, determining the ratio of different maturity stages in the female pollock population has very important implications for how scientists  calculate spawning biomass estimates, which in turn, are entered into statistical models to determine age class structures, overall population sizes, and, finally, catch quotas for the fishing industry.

On the males, we go by the following guidelines:

Immature male pollock have threadlike testes with a transparent membrane (that can be very hard to see).

Developing males have testes which look like smooth, uniformly textured ribbons.

Pre-spawning male testes appear as larger thicker ribbons.

Spawning males exhibit large testes that extrude sperm when pressed.

Spent males have large, flaccid, bloodshot, and watery testes.

These are the testes of a pre-spawning male
These are testes in the developing stage (Photo Credit: Story Miller, TAS 2010)

As for how they reproduce, pollock, like most fish, do external fertilization, which means they release eggs and sperm into the water, where they come together and fertilize.  For pollock in the northern Bering Sea, this tends to happen in the winter, from January-early April.  It appears that sub-populations in other areas of the Bering Sea and the Gulf of Alaska spawn during shorter time windows throughout the late winter and early spring.

Fish gather in large groups to spawn, and an individual female pollock can release anywhere from 10,000s – 100,000s of eggs in a single season!  They could also be released at one time or in several batches, called batch spawning.  Interestingly, if conditions are not optimal, such as low water temperatures or  poor nutrition, females can reabsorb eggs, in a process called atresia.

Here are several hundred pollock we have to sort from a typical catch!  We toss the  females in the"Sheilas" side and the males in the "Blokes" side!
Here are several hundred pollock we have to sort from a typical catch! We toss the females in the”Sheilas” side and the males in the “Blokes” side!

After spawning and fertilization, the resulting larvae grow into juveniles, the juveniles grow into adults, and the process starts anew!  Overall, scientists still have much to learn about the timing and mechanisms behind the pollock reproductive process— and I have enjoyed learning about it from the NOAA team!

Personal Log:

First, the answer was… 75 dozen eggs!  Those were some pretty close guesses, good job!

Let’s continue our tour aboard the Oscar Dyson!  Now, as you can imagine, safety and training are very important parts of life at sea.  I feel very confident in the crew and officers’ careful preparedness.  Each week, we conduct safety drills.  There are three types: man overboard, fire, and abandon ship.  For each drill, each member of the ship has to report to a certain station to check in.  In addition, you may be assigned to bring something, such as a radio, first aid kit, etc.

One of our many life rings
One of our many life rings

The drill I was most interested in was abandon ship, because not only do you carry your emergency survival (also known as an immersion) suit with you, but sometimes you practice putting it on!  I had seen many pictures of other Teachers at Sea wearing them and wanted the chance to try it on myself!

So, without further ado, here are Allan and I in our suits:

Survival Suit Stylin'
Survival Suit Stylin’

What do you think, do we look like Gumby???

So, how exactly does it work?  Well, it is a special type of waterproof dry suit that protects the wearer from hypothermia in cold water after abandoning a sinking or capsized vessel. It is made of stretchable flame retardant neoprene, and contains insulated gloves, reflective tape, whistle, and a face shield for spray protection.  The neoprene material is a synthetic rubber with closed-cell foam, which contains many tiny air bubbles, making the suit sufficiently buoyant to also be a personal flotation device.

There are various types of immersion suits.  Some contain:

  • An emergency strobe light beacon with a water-activated battery
  • An inflatable air bladder to lift the wearer’s head up out of the water
  • An emergency radio beacon locator
  • A “buddy line” to attach to others’ suits to keep a group together
  • Sea dye markers to increase visibility in water

We keep them in our rooms and there are many others placed throughout the ship in case we are not able to return to our rooms in a real emergency.

I hope that gives you a good feel for life onboard here in week two.  Please post a comment below, students, with any questions at all.

A nice sunny day in the Bering Sea!
A nice sunny day in the Bering Sea!

Johanna Mendillo: From Russia with Love… August 1, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA Ship Oscar Dyson
July 23 – August 10, 2012

Mission: Pollock Survey
Geographical area of the cruise: Bering Sea
Date: Wednesday, August 1, 2012

Location Data from the Bridge:
Latitude: 62  18’ N
Longitude: 178 51’ W
Ship speed:  2.5 knots (2.9 mph)

Weather Data from the Bridge:
Air temperature: 9.5C (49.1ºF)
Surface water temperature: 8.5C (47.3ºF)
Wind speed: 9.1 knots (10.5 mph)
Wind direction: 270T
Barometric pressure:  1001 millibar (0.99 atm)

Science and Technology Log:

In the last few days, we have crossed into the Russian Exclusive Economic Zone, sampled, and are now back on the U.S. side!   Unfortunately, students, there was no way for my passport to get stamped.  There was no formal ceremony, and we will cross back and forth many times in the next two weeks as we do our science transects, collecting Pollock, but the science team took a moment to celebrate— and I snapped a quick picture of the computer screen.

Crossing into Russia!
Crossing into the Russian Exclusive Economic Zone!

I would now like to introduce you to one of the most simple and valuable tools we use on board to measure a sample of Pollock- the Ichthystick.

The one... the only... Icthystick!
The one… the only… Ichthystick!

First, some background.  Each day we “go fishing” 2-4 times with our mid-water and bottom trawls. “Trawling” simply means dragging a large net through the water to collect fish (and you will learn more about the different types of nets we use quite soon).  After the trawl, we bring the net back on board and see what we have caught!

There are many types of data we collect from each catch- first and foremost, the total weight of the catch and the numbers and masses of any species we catch in addition to pollock.  So far, we have collected salmon, herring, cod, lumpsuckers, rock sole, arrowtooth flounder, Greenland turbot, and jellyfish on my shifts!  Our focus, though, of course, is pollock.  For pollock-specific data, we keep a sub-sample of the catch, usually 300-500 fish, for further analysis, and we release the rest back into the ocean.

From this sub-sample, I help the scientists collect gender and length data.  As I mentioned in my last post, we also collect otoliths from the sub-samples so that the age structure of the population can be studied back in Seattle.  The most straightforward and obvious data, though, is simply measuring the length of the fish, which takes us back to the wonderful contraption known as the Ichthystick!

Now, scientists cannot determines the age of a pollock simply from measuring its length- there are many factors that determine how fast a fish can grow, such as access to food, space, its overall health, environmental conditions, etc.  But, by collecting length data and combining it with age data from otoliths, scientists can begin to see the length ranges at each age class and the overall “big picture” for the population emerges.

And again, once the age structure and population size of pollock in the Bering Sea are determined for a certain year, management decisions can be made, commercial fish quotas are set for the upcoming fishing season, and there will still be a suitable population of fish left in the ocean to reproduce and keep the stocks at sustainable levels for upcoming years.

The Icthystick logo... designed by scientist Kresimir himself!
The Ichthystick logo… designed by scientist Kresimir!

So, it clearly does not make much sense to measure pollock with a ruler, paper, and pencil.  To measure hundreds of fish at a time, the NOAA team has developed a simple yet ingenious measuring tool, powered by magnets, and transmitted electronically back to their computers for easy analysis- the Ichthystick!

The Ichthystick may simply look like a large ruler, but it consists of a sensor and electronic processing board mounted in a protective (& waterproof!) container.  Inside, the sensor processes, formats and transmits the measurement values of each fish to an external computer that collects and stores the data.


Here I am...measuring away!
Here I am…measuring away!

Interestingly, the board works with magnets and makes use of the property of magnetostriction.

With magnetostriction, magnetic materials change shape when exposed to a magnetic field.  Magnetostrictive sensors can use this property to measure distances by calculating the “time of flight” for a sonic pulse generated in a magnetic filament when a measurement magnet is placed close to the sensor.  Here, in the picture, I am placing the fish along the sensor and holding the measurement magnet in my right hand.

Do you see stylus in my right hand?
Do you see stylus (containing the magnet) in my right hand?

To determine the distance to the measurement magnet, the elapsed time between when I touch the magnet to the board to generate the ultrasonic pulse and when the pulse is detected by the sensor is recorded– and that time is converted to a distance (using the speed of sound in that material), which is equal to the fish’s length!

Now, the “measurement magnet” is referred to as the “stylus”, and it is a little white plastic piece, the size of a magic marker cap, which contains the magnet embedded into the bottom.  You simply strap the stylus onto your index finger with velcro (so that the north pole of the magnet is facing down toward the sensor) and are ready to begin measuring!  The magnet inside is a small neodymium magnet, chosen because it has a very strong magnetic field.  Each time a measurement is recorded, a chime sounds, and I know I can go on to measuring my next fish!  At this point, I have measured a few thousand fish!

Personal Log:

Let’s continue our tour aboard the Oscar Dyson!  I think it is fair to say that scientific research makes one hungry!  I have enjoyed meeting Tim and Adam, the stewards (chefs) onboard the Dyson, devouring their delicious meals, and spending time talking with the officers and crew in the galley (kitchen) and mess (dining hall).  As you can see from my picture, the first thing you notice are the tennis balls on the bottoms of the chairs!  Why do you think they are there?

Look on the floor...
Look on the floor…

As in most things related to ship design, planning for rough seas is paramount!   So, in addition to tennis balls, which stop the chairs from sliding around, there are bungee cords that attach the chairs to the floor.  The dishes are also strapped down and most items are in boxes, bins, or behind closed doors.  But do not let that fool you— there is a LOT of food in there!  I have enjoyed many a midnight snack- fruit, yogurt, ice cream bars, cereal bars, cookies, and soup to name just a few.  In addition, there is a salad bar and a selection of leftover dinner items available to reheat each night.  Since I am on the 4pm-4am shift, I have been missing breakfast, and I have been told I must have at least one hot cooked-to-order meal before I depart!

Don't be late... or you will go hungry!
Don’t be late… or you will go hungry!
The Mess Rules!
The Mess rules!

I was a little surprised to see a mini-Starbucks on board too!  It is quite a setup, complete with pictures and directions on how to make each concoction:

Which kind would you order?
Which kind would you order?

Dennis, one of the Survey Technicians who works on the overnight shift with me, promised to make me a hazelnut latte if I could correctly predict the number of  pollock in a trawl, Price-Is-Right style.  I finally won a few nights ago….

Interestingly, there are no mechanisms in place to help the stewards cook in rough seas, but Adam assured me that he has never had a dinner for thirty slide off the grill and onto the floor!  Adam has been working in the NOAA fleet for over 10 yrs., including 7 yrs on the Miller Freeman, the precursor to the Oscar Dyson.  He has been onboard the Dyson for almost a year.  Tim has just joined the Dyson on this cruise and was previously in our home state— aboard the Delaware out of Woods Hole, Massachusetts!  Before joining NOAA, he worked on several supply ships that sailed across the world.  Each has been quite friendly and helpful as I learn to navigate my way around both the ship and my new schedule.  One of our frequent conversations is menu planning and the all-important-dessert on the schedule for each night.  So far, I have enjoyed apple cobbler, pineapple upside down cake, snickers cake, carrot cake, brownie sundaes, oatmeal raisin cookies, and… Boston cream pie!

Assistant Steward Adam
Assistant Steward Adam
Chief Steward Tim
Chief Steward Tim
Tim and Adam's domain... the Galley!
Tim and Adam’s domain… the Galley!

One last Q: How many dozens of eggs do you think Tim and Adam will go through on our 19-day cruise with 30 people on board?  Write your guess in the comment section and I will announce the answer in my next post…

Johanna Mendillo: Greetings from Alaska and the Bering Sea! July 27, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA Ship Oscar Dyson
July 23 – August 10, 2012

Mission: Pollock Survey
Geographical area of the cruise: Bering Sea
Date: Friday, July 27, 2012

Location Data from the Bridge:
Latitude: 63 12’ N
Longitude: 177 47’ W
Ship speed: 11.7 knots (13.5 mph)

Weather Data from the Bridge:
Air temperature: 7.2C (44.9ºF)
Surface water temperature: 7.2C (44.9ºF)
Wind speed: 13.3 knots (15.3 mph)
Wind direction: 299T
Barometric pressure: 1001 millibar (0.99 atm)


Science and Technology Log:

Greeting from the Bering Sea!  It was a long journey to get here, complete with bad weather, aborted landings on the Aleutians, a return and overnight in Anchorage, and lost luggage, but it was a good introduction to the whims of nature and a good reminder that the best laid intentions can often go awry.  As O’Bryant students know, our motto is PRIDE and the “P” stands for perseverance, so I simply stayed the course and made it to Dutch Harbor and NOAA Ship Oscar Dyson… only 29hrs late!

In upcoming posts, you will learn a lot about the acoustic technology, statistics, and the engineering know-how behind the trawling process and how it is used to find, collect, and study Pollock populations.  But first, let’s start with splitting open some fish heads!

Now that I have your attention, let me explain.  There are many steps involved in “processing” a net full of Pollock, and I will show you each soon, step-by-step.  I think it would be more fun, though, to jump ahead and show you one little project I helped with that literally had me slicing open fish heads…

Hard at work...
Hard at work…

Here I am preparing and cutting away!  The objective: remove the two largest otoliths, structures in the inner ear that are used by fish for balance, orientation and sound detection.  These are called the sagittae and are located just behind the fish’s eyes.  These otoliths can be measured– like tree rings — to determine the age of the fish because they accrete layers of calcium carbonate and a gelatinous matrix throughout their lives. The accretion rate varies with growth of the fish– often less growth in winter and more in summer– which results in the appearance of rings that resemble tree rings!

Time to cut...
Time to cut…

From a small sampling of otoliths, along with length data, projections can be made about the growth rates and ages of the entire Pollock population.  Such knowledge is, in turn, important for designing appropriate fisheries management policies.  Fisheries biologists like to think of otoliths as information storage units; a sort of CD-ROM in which the life and times of the fish are recorded.  If we learn the code, we can learn about that fish!

Can you spot the otolith?
Can you spot the otolith?

For each net of Pollock, we will collect 35 otoliths, which translates to approx. 1,500 otoliths from this cruise alone!  They will be sent back to Seattle and measured under the microscope this fall and winter.


Personal Log:

Wondering where I am at this very moment?  Check out NOAA Ship Oscar Dyson on NOAA Ship Tracker!

Small things become important when your daily life gets confined to a small space, right, students?  Perhaps some of you have been to sleepover camp and know firsthand?  In a few years, you will also experience communal living in close quarters— in college!  It only seems appropriate that I start by explaining to you (and showing you) my personal space aboard NOAA Ship Oscar Dyson!

First, my stateroom.  This picture shows you that I am in room 01-19-2.  I am on the 01-deck, and there are four other rooms on my hall that house most of the NOAA science team- Taina, Darin, Kresimir, Rick, and Allan.  Allan is my partner in crime- he is the other “Teacher at Sea” (TAS) onboard this cruise; he teaches high school science in Florida!  In addition to the NOAA team, Anatoli is a Russian scientist on board.  These NOAA scientists are based in Seattle in the Midwater Assessment & Conservation Engineering (MACE) group at the Alaska Fisheries Science Center and, depending on their schedules, come out to sea 1-4 times per year to collect data.  They are just one group of many NOAA teams conducting research in the Bering Sea; you will learn much more about the science team in later posts.

My door
My door

Originally, I was going to be bunking with the Chief Scientist, Taina!  However, one of the scientists was unable to join the trip, so Taina has her own quarters and I have mine!  This is quite the luxury, and it is very nice to know that I do not have to worry about waking up a roommate as I get ready for my shift.  Most roommates have opposite shifts, so each person gets at least a little bit of “alone time” in his/her room.  For example, Allan’s shift is 4am-4pm (0400-1600) and Kresimir’s shift is from 7pm-7am (1900-0700).

Here is my bunk!  I chose the bottom one, so if I fall out in rough seas, it is a shorter fall!  One trick- if the seas are rough, take the rubber survival suits and stuff them against the metal frames, so if I do smack against them, there will be some padding!  There is a reading light inside, and I also brought my trusty headlamp and pocket flashlight, so I should be pretty well set on any hasty exit I may have to make- such as for a safety drill!

My bunk!
My bunk!

I also have a desk and a locker, which is a closet for my clothes and other gear.  One thing ships excel at is maximizing small spaces with hooks- I have a row of hooks for my jackets, sweatshirts, hats, etc.  In the head (bathroom), there are many hooks as well.  The other neat trick—the use of bungee cords!  Here is one holding the head door open so it does not swing back and forth as the boat rolls.  They are also used throughout the ship to secure desk chairs, boxes, and any other object that could take flight during rough seas!

See the bungee cord?
See the bungee cord?

Since it is summer here in the high northern latitudes, the days are very long—sunset does not occur until about 12am each night and sunrise occurs around 7am.  The ships provides shades on both the bunks and the port holes (windows) to help people sleep, but as you can see, the earlier tenant in my room even added a layer of cardboard!

My window...
My window…

There are a few other features that help define life at sea.  The shower curtain has magnets to help secure it to the walls.  As you can see, it is a pretty tiny shower, and that handle could become essential if I chose to take a shower and then the seas turn rough!   The medicine cabinet locks shut, and if you leave it open, the door can swing during a big wave and smack you in the face!  Lastly, the head includes special digesting bacteria, so you can only use a special cleaner that does not kill them by accident!  There is a very powerful FLUSH noise that takes a little bit of getting used to as well– it scared me the first time I heard it!

Spot the shower handle...
Spot the shower handle…

That about does it for our first tour.  Please post a comment below, students, with any questions at all.  In my next post, I will give you a tour of the second most important area in daily life— the mess, where I eat!

Johanna Mendillo: Alaska Bound! July 13, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA Ship Oscar Dyson
July 23 – August 10, 2012

Mission: Pollock Survey
Geographical area of the cruise: Bering Sea
Date: Friday, July 13, 2012

Introductory Blog 

Hello everyone!  It is finally time– I am getting ready for my journey to sea.  What a journey this will be!  To Alaska, and the Bering Sea, to be exact.  I am very excited to share this work with you– both on the blog this summer and back at school in the fall.  As I learn more about NOAA, my ship (the Oscar Dyson), and the research work on Pollock, so will you!

First off, the basics.  What do you know about Alaska?  The Bering Sea?  The species Pollock?  If you are like me, there are probably a million or so questions on each running through your head.  So, those are the three topics I began to research first.  Here is what I learned:


Alaska is a vast and fascinating state.  It will also be the 40th state I visit!

Map of Alaska and Bering Sea
Map of Alaska and Bering Sea

State Capital: Juneau, located in the Southeast region of Alaska, has a population of 31,275 (according to the 2010 Census)

The Name: “Alaska” is derived from the Aleut word “Alyeska,” meaning “great land.”

State Flower: The forget-me-not!

State Gem: Jade.  Alaska has large deposits, including an entire mountain of jade on the Seward Peninsula!

State Mineral: Gold!  Perhaps I will find some on my journey?  Gold has played a major role in Alaska’s history.

State Tree: The tall, stately Sitka spruce; it is found in southeastern and central Alaska.

State Fish: The huge king salmon (also called Chinook), which can weigh up to 100 pounds.

Fun Fact: Secretary of State William H. Seward arranged for the United States to purchase Alaska from Russia in 1867 for $7.2 million dollars— or 2 cents per acre!

The Bering Sea

The Bering Sea, a northern extension of the Pacific Ocean, separates two continents- Asia and North America.  Covering over two-million sq. km (775,000 sq mi), the sea is bordered in the west by Russia and the Kamchatka Peninsula; in the south by the Aleutian Islands; in the north by the Bering Strait and the Arctic Ocean; and in the east by Alaska.  It is the third largest sea in the world and home to some of the richest fisheries in the world!

There is a donut in the Bering Sea?  Well, not exactly, but there is “The Donut Hole”—let me explain.  The Western side of the Bering Sea, out to 200 miles from shore, is Russian territory, and the first 200 miles offshore on the Eastern side belongs to the United States.  The section in-between, which lies 200 miles out from the coastlines of both countries, is known as “The Donut Hole,” and is considered international waters.  This area comprises 10% of the Bering Sea.

Fig. 1
Bering Sea “Donut Hole”

Now, as I had mentioned above, the Bering Sea is one of the world’s most productive fishing grounds, producing huge quantities of king crab, salmon, pollock, and other varieties of fish.  In addition, it is home to vast quantities of wildlife, including many species of whales, walrus, and millions of seabirds!  I can’t wait to take lots of pictures and videos for you to see!

Now, when many folks think of the Bering Sea, they think of the TV show “The Deadliest Catch”!  Are any of you fans?  Well, it is true that the Bering Sea is one of the most dangerous bodies of water in the world, and waves can easily reach 30-40 feet high.  Let’s hope we do not encounter too many of those this summer!


OK, so here is perhaps your first look at a Pollock!

Plenty of pollock!
Plenty of pollock!

Did you know:

  • Pollock has consistently been one of the top five seafood species consumed in the U.S.
  • Since 2001, U.S. commercial landings of Pollock (primarily in Alaska) have been well over 2 billion pounds each year.
  • Pollock are mid-water schooling fish that can live up to 15 years.
  • All Pollock is wild-caught in the ocean.  There is no commercial aquaculture for this species.

The wild fishery for Alaska Pollock, also known as Walleye Pollock, is the largest by volume in the United States and is also one of the largest in the world!  If you are a fan of fish sticks, chances are you have eaten Pollock!  FYI, Alaska Pollock is a different species than the Pollock found on the Atlantic coast.

It is primarily harvested by trawl vessels, which tow nets through the middle of the water column.  Some vessels are known as catcher/processors because they are large enough to catch their own fish and then process and freeze them at sea.  Other vessels deliver their catch to mother ships (at-sea processing vessels that do not catch their own fish) or to shore-side seafood processors.

Pollock is a high protein, low fat fish with a mild-flavor and a delicate and flaky texture.  Because of its adaptability, Pollock is consumed in a variety of forms that include fresh and frozen fillets, fish sticks and other breaded and battered fish products, and “surimi” products.

What is surimi, you ask?  Surimi products are formulated to imitate crab, shrimp and scallop meat and then marketed in the U.S. as imitation crab, shrimp or lobster.  They are often the “seafood” in seafood salads, stuffed entrees, and other products!  Surimi is produced by mincing and washing Alaskan Pollock fillets and then adding other ingredients to stabilize the protein in the fish and enable it to be frozen for extended periods of time.  Alaska Pollock fillets or mince is also frozen into blocks and used to produce fish sticks and used in a variety of products in fast food restaurants.

The Pollock fishery is highly regulated by the U.S. Federal government through the National Marine Fisheries Service (NMFS) and the North Pacific Fishery Management Council (NPFMC).  On the Eastern end, the Russian State Fisheries Committee handles government oversight.  Annual catch limits (called quotas) and seasons are set for Pollock fisheries, and limits are also set for bycatch species that may be caught unintentionally when fishing for Pollock.

In the next few days, I will continue to learn and prepare, so please send me any questions you’d like and leave comments below!  My next post will be from Alaska…stay tuned!