Saturday, 13 September 2008

Another day, another trawl!

After the morning shift had a pretty easy day due to very rugged bottom terrain (even a canyon got in the way!), the Nansen finally managed to deploy a bottom trawl during my afternoon shift yesterday (12th September). On the left, you can see Henning manning the trawl winches.



Looks like the trawl managed to go over some reef-y terrain, as we got a lot of reef associated species, like damselfishes and cardinalfishes and a couple of cleaner wrasses and anthiines, and there were quite a few corals and sponges in the trawl net too; the corals looked mostly like Tubastrea-type corals to me (I'm not much good at coral ID!). To the right, some of the science team are picking through the coral rubble for fishes.

A few of the fishes made it through the trawl okay, including another zebra shark and two remoras. Jens-Otto decided it would be cool to try and keep the smaller reef fishes for a few days so that we might have something swimming around to show to the people who visit the ship in Toamasina next week. He found one of Sven's primary production acrylic tanks in the hold under the trawl deck and converted it with the cunning use of duct tape and some kind of glue to seal the holes in the sides and anchor a tap into them. To the left, you can see Jéssica and Bradley with the second zebra shark (Stegostoma fasciatum) of the trip. This one fought back a bit and was slapping Jéssica and Bradley with its long tail all the way across the deck to the JESRT "rescue tank"!

To the left, you can see the top of the head of one of the two remoras, Echeneis naucrates we caught in the trawl. You don't often see the top of their head as they're usually stuck onto something. This "sucker" is actually a highly modified dorsal fin; the remora can flex the muscles associated with the ridges you can see (termed lamellae) in order to create a sucker-disc like effect, anchoring it to whatever it wants to be anchored to. Including people, as you'll see Bradley displaying below. Interestingly, my google search to get the fishbase page on this species also turned up an image of this species attached to a zebra shark!

We also did a trawl in the early hours of this morning, which netted a massive catch - 2 whole squid (yes that was it), which you can see to the left!








We are currently around here, doing another CTD line.
Photos courtesy Bradley Flynn (2), James Stapley (4).

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