Kaitlin Baird: Let the Fishing Begin! September 8, 2012

Other than testing out the FSCS today and learning the ropes, I also learned about another type of tow we are doing on this cruise. When looking at fish stock assessment it is also important to look at the base of the food chain, you guessed it, plankton. Today we were specifically targeting zooplankton, microscopic animal drifters in the ocean that are an important food source for many of the fish and other invertebrates that we are surveying.

When I saw the nets go in, they looked a bit different than those on the R/V HSBC Atlantic Explorer, and I learned a new term, BONGO net. This is the tandem net which we are using  to tow for zooplankton at set locations while we are en route. Unlike the trawl net we tow these on the side of the ship verses the back so there is no interference by the wake made by the ship as it moves through the water. If you imagine a giant windsock with a plastic catchment at the end, this is what these nets look like. The pressure of the water moving through the net forces anything heavy to the “cod end” of the net and sieves the water out of the mesh that makes up the net.

The depth of the net tow is dependent upon bottom depth and protocol at each site, but they normally try to tow pretty close to the bottom (=/- 10 m). A separate, Conductivity, Temperature and Depth (CTD) recorder is also deployed with the nets to understand more about the ocean chemistry at set locations.  There is such a variability when towing for plankton (as it can be quite patchy) that having the two nets gives you more opportunity to capture the diversity of life that is out there. The nets are also two different mesh sizes so that they can catch zooplankton in different size classes.

It was great to get fishing today off of the coast of Maryland. We were all ready to sort anything that came down the conveyer belt. The species get sorted and then brought to the FSCS stations. Here they are measured along with anything else that needs to be done to them. I helped to get otoliths prepared and input data on gut contents, condition and sex.

One of the things I noticed were a lot of flounders, both left eye and right eye. That’s right folks, flounder usually start with one eye on each side of their heads and then eventually (species dependent) it migrates as they mature so that they sit on the bottom with both eyes on top of their heads. Depending on which way they migrate they are designated as “left eye” or “right eye” as you can see in the photos below. Did you know? These eyes can move independently of each other, pretty cool stuff!

Stay tuned for more critters! Here is just a shortlist of some that we saw today!

Rosette Skate
Little Skate
Tilefish
Goosefish
Chain dogfish
Fawn cusk-eel
Gulf stream flounder
Four spot flounder
Silver hake
Armored sea robin
LOTS of Squid

Bye for now!