Power is a Factor
Higher power can add both detail and range to what you are seeing on the screen of your fish finder. Six-hundred-watt transducers are the most common. Some fish finders are capable of producing 1,000 watts or more. This can increase target resolution to improve bottom-structure detail and help distinguish the bottom from bottom-feeding fish at greater depths. Transducers of 1,000 watts or greater are physically larger, requiring bigger fairing blocks, and add to the cost or your total depth-sounder/fish-finder investment.