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Build your own automatic fishing machine

Sarah Thompson

22 June, 2022

Here’s a chance to create your own automatic fishing machine inspired by Aboriginal engineering.

Automatic fishing machines were, and may still be, used by Aboriginal people to catch fish in shallow waters. This activity is based on a fishing machine invented by Aboriginal engineers and used near the Murray River.

A clever design

The automatic fishing machine starts with an underwater fence, which goes across a waterway. There’s an opening in the fence, which is where the trap is set.

Illustration of a fish trap with netting across the river.

A strong but flexible stick is pushed into the riverbed and a line (string) is attached to the thin end of the stick. The line is pulled down tightly and secured underwater using a wooden peg. A loop on the end of the line is carefully fitted to the opening in the fence.

Illustration of a fish trap shown in cross section

When a fish travels through the loop, it gets caught. As it tries to escape, it will undo the peg and set off the trap. Then the fish gets flung out of the water!

Make a model machine

Let’s make a model automatic fishing machine. Models are a good way to test ideas and see how they work at a smaller scale.

You will need

2 butternut pumpkin halves
Vegetable peeler
Wooden skewers
Toothpicks
String
Scissors

What to do

Place the pumpkin halves flat side down. The pumpkin will represent the riverbed and enable you to secure your automatic fishing machine. Use a vegetable peeler to carefully remove some of the tough skin in the middle of the pumpkin halves.
Create your stick using wooden skewers. You can use a single skewer or build a larger stick using multiple skewers and string. Remember that you’re going to push this stick into a pumpkin, so make sure the pointy bits are at the right end!
Cut an arms-length piece of string and tie it to the other end of the stick.
Carefully poke the stick into one of the pumpkin halves on a slight angle. Make sure it is deep enough to feel secure when you bend the stick.
Pull the string down to bend the stick, and then find a spot a couple of centimetres above the other pumpkin. Tie a toothpick to this point on the string.
Insert toothpicks into the other pumpkin half to create two pegs, that each resemble an X.
Slide the toothpick out from the knot and re-thread it through the first peg, back through the knot and then through the second peg. The idea is that the pegs will keep the string tight and the stick bent. You may need to add more pegs or adjust how the toothpicks cross to achieve this.
Your trap is now ready. Simply tug on the end of the string to set it off!