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How does a Fish Finder work?

Physics | 7-14 yrs | Interactive, Learning Pod

What is a fish finder?

A fish finder is a device used by fisherman to locate fish underwater. It uses sonar to understand where the fish are by mapping the pulses of sound energy which are reflected. These sound waves bounce off schools of fish and reflects back to the fish-finder. A display panel on the fish-finder tells the fishermen where the fish are.

Fish finders and Fathometers

Fish finders are used by both commercial as well as sport fisherman, who can use the sonar to locate fish, underwater debris and to map the bottom of a body of water. Fish finders have been derived from fathometers, which are sonar instruments used for navigation and safety and determine the depth of water.

How does it work?

A fish finder sends a sound wave into the water, when it strikes an object such as a fish, the sound wave is reflected back. This reflection gives an idea of the size, shape and composition of the object. To be more precise, the frequency and power of the sound wave is taken into consideration. The distance of the object underwater can be gauged based on the speed of the sound wave in the water.

Project –

  • Classify these fish (sharks, whales, crabs, prawns, tuna, salmon, king fish, squid) into shallow water or deep sea fish.
  • What is the difference between a fresh water fish and a salt water fish?
  • Try your hand at fishing at a nearby pond, lake or even the sea. Ensure you are accompanied by an elder for this project. All you need for the activity is a good sturdy stick, some rope, a hook and some dough. Assemble your fishing rod, and go fishing!