Science & Technology Log: walleye pollock, which is an important fish species here in Alaska. Walleye pollock make up 56.3% of the groundfish catch in Alaska (http://www.afsc.noaa.gov/species/pollock.php), and chances are you’ve eaten it before. It’s a commonly used fish in all of the fast food restaurants, in fish sticks, and it’s also used to make imitation crab meat.
Our first catch had a little over 300 walleye pollock, and we processed all of them. Three hundred is an ideal sample size for this species. If, for example, we had caught 2,000 pollock, we would only have processed 300 of the fish, and we would have released the rest of them back into the ocean. Check out the photos/captions below to see how we process the catch.
We also removed and preserved 20 stomachs from randomly selected fish in order to (later) analyze what they had been eating prior to them being caught. One of the last things we do is collect otoliths from each of those 20 fish. Otoliths are ear bones, and they are used to determine the age of a fish- they have rings, similar to what you see in trees.
Here’s a look at some of the bycatch in our nets:
We passed by Dutch Harbor yesterday- it should sound familiar if you watch Deadliest Catch. We didn’t go into the Harbor, so no, I didn’t see any of the crab boats or any of the guys from the show! Below are some pics of the Aleutian Islands that I’ve see thus far…many more to come, since we still have another 13 days (give or take) of sailing left!
QUESTION(S) OF THE DAY:
- The Aleutian Islands were formed at the boundary where the North American and Pacific Plates are coming together. The Pacific Plate is denser than the North American Plate, so it slides underneath the North American Plate. What is this type of plate boundary called (where plates move towards each other), and what is it called when one plate slides underneath another?
- One thing we’re doing on this trip is trawling for fish. We are conducting both mid-water and bottom trawls. Describe one advantage and one disadvantage to trawling in order to gather scientific data.