Wednesday, May 2, 2007

Hey Guys! The next batch of pictures are finally in! This week we have been doing a lot of field work where we do abundance and diversity counts. Our first site was Yaquina Bay. We collected shallow bay fishes using a net called a "seine". This net has lead weights on the bottom, floats on the top and two poles, one on each end, to hold it by. To take samples with the seine, one person has to wade into the water as deep as they can go while the other walks along side the water's edge with the second pole.
Once you have gone a certain distance you bring the net in and collect all of the fish. In this field sample we found several silversides, chum salmon, bay pipefish, english sole, and several varieties of sculpin. This picture is of "Gary", a staghorn sculpin that we took back to lab. We are trying to feed him while we are studying him, but he is incredibly picky so he may have an early release. You can tell many sculpin species apart by pushing on the top of their head. Gary has three points that stick out when you do this, like a staghorn deer!


Our second field collection was aboard the Elakha. We were still sampling the Yaquina Bay, but this time we did it by trawling several meters down. Many of you have probably seen trawling nets before (a ton of zombie-like fish get stuck in one in Finding Nemo), but if you haven't, I found a great image on the web. On each side there are boards that are held "open" by the force of the water as the boat moves. This is so that the net stays open. Our net was a little different from this image. First of all it wasn't nearly as big, and second we didn't have (or need) a TED. TEDs are metal grates that help sea turtles escape the trawl nets in larger set-ups. The hydraulics on the boat do a lot of the lifting when the sampling is done, but the end part you have to pull up onto the boat by hand (notice that the girls are hauling in the net and the guys are watching...).


After we pull the net in, we do the same thing that we did with the seine. We remove the fish, record them, and release them back into the bay. I thought we would get much bigger fish when we used the boat, but the largest fish we got was a starry flounder (only about 10 cm). We did get a really cool snake prickleback though!

1 comment:

Anonymous said...

So, one silverside says to the other, am I just crazy, or are we "IN SEINE"?