The working principle behind a fish finder is based on echolocation technology. It operates by first emitting a sonar signal outward, then capturing the echo reflected back after the signal encounters an object. By calculating the time delay between emission and return, the device determines the distance to the object. The first prototype of echolocation technology was developed in the early 20th century. World War I became a major driving force for its advancement, as the urgent need to detect enemy submarines pushed the development of related technologies. However, during that era, echolocation devices were large and cumbersome to operate.
Over time, these instruments became more accurate and compact. Still, they remained almost exclusively used by the military until the end of World War II. In the 1950s, renowned explorer and experienced fisherman Carl Lowrance, along with his sons, began developing a small, civilian-use sonar device designed specifically for fishing. Based on their underwater research experience, Lowrance believed there would be strong market demand for such equipment. Research showed that in a typical aquatic environment, as much as 90% of fish are concentrated in only 10% of the water area. Moreover, fish distribution is influenced by numerous factors, including time of day, water temperature, sunlight, wind direction, and food availability. As a result, fish are constantly moving to adapt to these environmental changes. The Lowrance family succeeded in miniaturizing the sonar device by using transistor technology instead of traditional vacuum tubes. In 1957, the world’s first compact fish finder was launched by a company named Lowrance, specifically designed for recreational fishing.