Jacob Tanenbaum, Final Day of the Survey, May 27, 2007

NOAA Teacher At Sea: Jacob Tanenbaum
Mission: Fisheries Oceanography Coordinated Investigations
Day 9: May 27, 2007
Snuggy in the captain’s chair
Weather Data from the Bridge:
Visibility: 10 Miles
Wind Speed: 20 Kts.Sea Wave Height: 2
Water Temperature: 4.7 Degrees Celsius
Air Temperature: 6 Degrees Celsius
Pressure: 1010.7 MbsPersonal Log

We reach Kodiak in the morning. I am excited to be seeing Kodiak, but sad to be leaving the ship. It has been a wonderful 10 days at sea. Please check back
tomorrow. I should be able to do a blog entry from the hotel in Kodiak and I can show you this incredible island. My heartfelt thanks to everyone on the
ship who gave me such a wonderful welcome and who gave such support to this project.

Here are a few last photos from around the ship: Snuggy in the Captains chair and Snuggy at the wheel of the ship.

Snuggy steering the ship
Snuggy steering the ship

Science Log:

Today was an important part of the cruise. On section, in addition to thebongo nets, we also deployed an instrument called a CTD array. This array allows the scientists to sample water at different depths. This is very importantin oceanography because the water lower down is very different from thewater higher up in the water column. The chemistry changes as you go down, the temperature changes and the creatures living at each depth may be different from the creatures above or below. Want to learn more about this important research? Click here for a video. We also stopped to have some fun with the CTD.


We attached someStyrofoam cups to the array and watched what happens when the pressure at depth presses in on them. Click here for a video.

Presurized Styrofoam cup


We are coming to the end of the cruise now. We deployed the bongos 125 times and have done 8 CTD’s, and released one drifter buoy. The scientists had
wanted to do more. They had planed 169 bongo deployments, but the bad weather forced us to change our plans. “That is the way things go out here,” says
Chief Scientist Annette Dougherty. Lets talk to her more about what we have learned so far on this cruise:

Tell us what you have learned so far:

On the standardized grid we have been doing, the numbers of Pollock are low, but spread out across the grid. The fish are also small. 4.5 to 6.5 mm. Which
is considerably smaller than last year.What does that mean?

It is a colder year and a very turbulent year, with a lot of storms, and what that can do is flush things out through the strait we are sailing in. The
fish may have spawned late. Or we could be catching the end of the hatching. It is hard to predict how many Pollock return as spawners if you can’t be out
here all the time.

So what does the survey tell us?

This is a colder year, and the growth rate has been slow. They are eating, so it does not mean they will not survive. There is a lot of stuff out there.

The study mainly tells us about the early life history. About what the fish goes through from hatch to spawning. The egg is the strongest stage these fish
have. After they hatch, they have a short time to use their yolk sack before they have to start to feed. If they can learn to feed! Some fish are stupid
and they can’t figure that out and just die. Most figure it out because they have to grow. There is mortality around every corner for these fish. They flow
with this current stream – well what if there is not food where it takes them? What if they don’t develop as fast as the fish up stream? They will be
competing for the same food. There is a lot against these fish, and they manage to survive. Females produce thousands of eggs, but very few survive. There
are a lot of hungry mouths out there!

What happens next in the study:

The database that we have been entering numbers into will go into a centralized database. I will also build a cruise report from that. It will state
general numbers and what grid stations they occupied. The numbers that we put in are preliminary estimates of the population. We wait until the samples
come back from Poland. They will be very meticulously sorted. Those final numbers are what we use for larval abundance (the number of Pollock babies).

How many years has this study been going on?

The study has been going on for 21 years now.

What have you learned in that time?

It is amazing how much things vary from year to year. It is hard to predict, based on a few environmental variables what will happen to these fish. You
have to have patience. This could be a good recruitment year. We could have missed them.

When will you know for sure if it was a strong year?

We will have to wait for 3 to 4 years to decide how many will spawn. Next year in the March survey, we will be able to see how many we catch as
one-year-olds. They go through their first year, which is very hard for them.

What is next for you?

I have a whole lot of otoliths (ear-bone samples) to read from another survey. I come back in September with Mat Wilson to see these same fish as what we
call age-zero. They do a lot of growing between now and then. They don’t have a vertebra right now. They can’t swim against the current yet. At about 12
millimeters, they will begin to grow bones. That is the beginning of juvenal transformation. They will look like miniature adults in September. They are a
beautiful golden bronze.

Leave a Reply

%d bloggers like this: