In order for our Hunger Games inspired behavior experiment to work, we obviously need brave tributes to fight in the arena. We decided on the shrimp species Crangon crangon to be our contestant facing the frightening green shore crab Carcinus maenas.
Consequently, one of our first important jobs was to fish for our protagonists and the villains. The first days, while we were exploring the islands of Tjärnö and Saltö, where the marine station is located, we noticed that the shrimps are hanging out quite close to shore in the shallow water. They are not at all afraid but rather curious and bold enough to swim up to one’s feet to closely observe if there is anything interesting to find between the toes. So, we knew we wouldn’t have to far find for our new favorite invertebrates.
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| Our first attempt in finding some potential tributes. Some team members were not used to the “freezing” Swedish water temperatures (22°C). |
Hand nets, purse seines and traps
During the past few days several techniques were tried to catch the quite fast crustaceans, which easily escaped our hands with a powerful backwards kick using their tails.
The easiest and also most straight-forward approach we could think of was to use simple hand nets and it turned out to be quite efficient. Especially, when pulling the nets through bigger seagrass patches, you can be sure to catch a bunch of shrimps. As the species we are looking for stays usually close to the bottom than inside the seaweed, we decided to try a beach seine net, with which we hoped to catch a large number of shrimps at once. This net has to be pulled by two people and a heavy rope helps to keep the net on the bottom, so nothing can escapes (and by nothing I mean literally nothing). Long story short, we caught large amounts of seaweed, juvenile fish and small crabs but only few shrimp and in the end the cleaning of the net took us longer than the actual fishing…so fishing with hand nets it is. From now on, every evening two members of our group will go on the hunt for the next Katnisses and Peetas for the following day.
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| Kate proofs that fishing for shrimp can also be romantic...you just have to do it during sunset. |
The crabs play hard to catch
In contrast to the shrimp, the crabs didn’t seem to be very keen on ending up in our experimental tanks. Once spotted, they quickly disappear between the rocks of the close shore, where no net can reach them. We figured out that the most promising spot to catch crabs was underneath the pier in front of the institute. The water there is quite dark and muddy, which significantly decreased our success rate of catching the desired crustacean. We managed to capture a few using the hand nets but no one of the team was very keen on wading underneath the pier every evening a different method had to be found.
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| In order to catch a crab, you have to become a crab |
Luckily, our friendly fellow students gave us the hint that they are easily caught with traps, that can be found in the fishing gear shed of the institute, with just a crushed mussel as bait. This was soon tried out and already the first attempt was as successful as a whole hour of snorkeling and wading with hand nets, with three big crabs inside the trap!
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| Some not so happy crabs made us very happy, especially because we don’t have to go fishing underneath the pier anymore |
Now that we figured out how and where to get all the specimen we need every day for our experiments, we can fully start with as many “arena fights” as the time allows.
And don’t worry, unlike in the actual movie, all our tributes make it out of the arena alive and no crabs were or are being harmed during the experiment :-)
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