Kathleen Harrison: Fish Stick, Anyone? July 15, 2011


NOAA Teacher at Sea
Kathleen Harrison
Aboard NOAA Ship  Oscar Dyson
July 4 — 22, 2011

Location:  Gulf of Alaska
Mission:  Walleye Pollock Survey
Date: July 15, 2011

Weather Data from the Bridge
True Wind Speed:  34 knots, True Wind Direction:  284.43
Sea Temperature:  10.02° C, Air Temperature:  11.34° C
Air Pressure:  1014.97 mb
Latitude:  56.12° N, Longitude:  152.51° W
Sunny, Clear, Windy, 10 foot swells
Ship speed:  10 knots, Ship heading:  60°

Science and Technology Log

The Walleye Pollock is an important economic species for the state of Alaska.  It is the fish used in fish sticks, fish patties, and other processed fish products.  Every year, 1 million tons of Pollock  are processed in Alaska, making it the largest fishery in the United States by volume.  The gear used to catch Pollock is a mid-water trawl, which does not harm the ocean floor, and hauls are mostly Pollock, so there is very little bycatch.

table full of pollock
A sample of pollock that the Oscar Dyson caught for scientific study. A "drop" in a very large "ocean" of pollock industry.

Although Pollock fishermen would like to make as much money as they can, they have to follow fishing regulations, called quotas, that are set each year by the North Pacific Fishery Management Council (NPFMC).  The quotas tell the fishermen how many tons of pollock they can catch and sell, as well as the fish size, location, and season.  The NOAA scientists on board NOAA Ship Oscar Dyson have an important role to play in helping the NPFMC determine what the quotas are, based on the biomass they calculate.

The quotas are set in order to prevent overfishing.  Pollock reproduce and grow quickly, which makes them a little easier to manage.  When fishing is uncontrolled, the number of fish becomes too low, and the population can’t sustain itself.  Imagine being the lone human in the United States, and you are trying to find another human, located in Europe, only you don’t know if he is there, and all you have is your voice for communication, and your feet for traveling.  This is what happens when fish numbers are very low– it is hard for them to find each other.

There are many situations where uncontrolled fishing has cost the fishermen their livelihood. For example, in the early 1900s, the Peruvian Anchovy was big business in the Southeast Pacific Ocean.  Over 100 canneries were built, and hundreds of people  were employed.

anchovy catch graph
This graph shows how the Peruvian Anchovy catch rose to record heights in 1970, then collapsed in 1972. This could have been prevented by effective fishery management.

Scientists warned the fishermen in the 1960s that if they didn’t slow down, the anchovies would soon be gone.  The industry was slow to catch on, and the anchovy industry crashed in 1972.  The canneries closed, and many people lost their jobs.  This was an important lesson to commercial fishermen everywhere.

The Walleye Pollock (Theragra chalchogramm) is a handsome fish, about 2 feet long, and greyish – brown.  Most fishermen consider him the “dog” food of fish, since he pales in comparison to the mighty (and tasty) salmon.  Nonetheless, Pollock are plentiful, easy to catch, and thousands of children the world over love their fish sticks.

Besides calculating biomass, there are 2 other studies going on with the Pollock and other fish in the catch.  Scientists back at the Alaska Fisheries Science Center (AFSC) in Seattle are interested in how old the fish are, and this can be determined by examining the otoliths.

2 pollock otoliths
Here are 2 otoliths from a pollock. The one on the left shows the convex surface, the other shows the concave surface.

These are 2 bones in the head of a fish that help with hearing, as well as balance.  Fish otoliths are enlarged each year with a new layer of calcium carbonate and gelatinous matrix, called annuli, and counting the annuli tells the scientists the age of the fish.  Not only that, with sophisticated chemical techniques, migration pathways can be determined.  Amazing, right?  The otoliths are removed from the fish, and placed in a vial with preservative.  The scientists in Seattle eagerly await the return of the Oscar Dyson, so that they can examine the new set of otoliths.  By keeping track of the age of the fish, the scientists can see if the population has a healthy distribution of different ages, and are reproducing at a sustainable rate.

Another ongoing study concerning the Pollock, and any other species of fish that are caught during the Pollock Survey, deals with what the fish eat.

stomach being put into a bag for later study
A pollock stomach is put into a fabric bag, which will be placed in preservative. Scientists at the Alaska Fisheries Science Center will study the contents to determine what the fish had for lunch.

Stomachs are removed from a random group of fish, and placed into fabric bags with an ID tag.  These are placed into preservative, and taken to Seattle.  There, scientists will examine the stomach contents, and determine what the fish had for lunch.

Personal Log  

I learned about fishing boundaries, or territorial seas, today.  In the United States, there is a 12-mile boundary from the shore marked on nautical charts.  Inside this boundary, the state determines what the rules about fishing are.  How many of each species can be kept, what months of the year fishing can occur, and what size fish has to be thrown back.   Foreign ships are allowed innocent passage through the territorial seas, but they are not allowed to fish or look for resources.  Outside of that is the Economic Exclusion Zone (EEZ) which is 200 miles off shore.  The EEZ exists world-wide, with the understanding among all international ships, that permits are required for traveling or fishing through an EEZ that does not belong to the ship’s native country.

Everyone was tired at the end of the day, just walking across the deck requires a lot more energy when there are 10-foot swells.  Check out this video for the rolling and pitching of the ship today.

2 Replies to “Kathleen Harrison: Fish Stick, Anyone? July 15, 2011”

  1. Hello, Ms.Harrison
    this blog entry was very interesting I didn’t know that the Walleye Pollock was an very important economic species for Alaska, let alone the main fish used in fish patties, fish sticks, and processed fish products. I always wondered what kind of fish was used in fish stiks and fish food products. It is very important and smart for the North Pacific Fishery Management Council to have quotas set each year to notify fishermen how manny tons of pollock they can sell, fish, and more. So that the industy wont collapse.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s