Here Fishy, Fishy

*** As I was working these tows  many of the photos are not mine. They are used with permission.

A small, but very important part of this cruise is collecting data on the larger (fishable) fish in the area. Right now the only commercial fishery in the region is for krill. BUT, two species of ice fish may have recovered from overfishing that occurred in the 1960s and 1970s. It is possible that an icefish fishery might open in the region in the next few years. So the fish scientists onboard want to get a better idea of the winter distribution and abundance of  ice fish.

That means we go fishing. Just like commercial fishermen, we carefully pick the times and locations to maximize the number of fish we will catch. Unlike commercial fishermen we are intentionally using a small net and trying to keep it off the bottom to reduce by-catch  (all the non-fish critters that end up in the net).

Despite our best efforts, we do catch a lot of benthic invertebrates. That’s where the zooplankton team steps in to quickly sort the catch so that we can get the animals back in the ocean quickly. I like to think that if we can turn the catch around in less than an hour a good portion of the invertebrates will live to tell the story of the their alien abduction.

So let’s go fishing.

For commercial fisheries you would use net doors  that  are made of steel and weigh 1 ton (or more) each. Since our net is so little (only a fifteen foot otter trawl), we are using aluminum doors that weigh about 150 (or so) pounds each. The net doors serve to keep the net open so that it will catch fish.  The smaller the net, the smaller the doors need to be.

Once the full net is brought onboard.  It is unceremoniously dumped onto deck and shoveled into baskets..

Sometimes we do a rough sort just to remove the fish and estimate how much “other stuff” we caught. We actually get mostly “other stuff” and relatively little fish per tow.

Last night we did a tow where we only did a rough sort. We had 24 baskets of sponges (about 750 pounds) and about 50 pounds of other benthic animals. We also caught 40 (not pounds, just forty) small fish.That was a lot of stuff for 4 people to sort through in 30 minutes.

When we have time, we like to do more thorough sorts and identify the benthic critters to phylum, and when possible, species.

CCAMLR, the Antarctic marine species Treaty, requires that we report “Vulnerable Marine Ecosystems” or VMEs. CCAMLR recognizes that some marine ecosystems are composed of animals that are very sensitive to disturbance. These animals tend to be long lived and slow growing and often provide structure (habitat) on the sea floor.  It includes things like corals and glass and sponges. If we catch a certain amount of those critters, it must be reported to CCAMLR, and that area will be closed for fishing. We can quickly identify these sensitive species even in our rough sorts.

We catch some very cool things…

 

You can see a glass sponge and an octopus in the bottom left corner.  Solitary cup corals are in the center.  On the bottom right there is an armored chiton (red)  and a pycnogonid  (sea spider- we catch a lot of pycnogonids)

Here’s a close up of that bristle worm.   You see where it gets its name

My favorite by far are the cyrollid amphipods which I have dubbed space cockroaches

I really need to spend less time working and more time taking photos, but my shift has been pretty full on and I don’t think Andrew would like it if I got his camera covered in mud and salt water. It’s a good thing I have friends on other shifts who can stay clean and take photos they are happy to share.