Portable scientific system for lakes
For assessment of fish, plankton and macrophytes in lakes, mobile surveys from small boats are conducted with the acoustic beam pointing from the surface towards the bottom.
For assessment of fish close to the surface, the acoustic beam must be pointed horizontally.
The most typical lake application is estimation of fish abundance. Often, surveys are run during the night since fish during the dark hours are distributed in the open water and are not hiding in daytime refugees.
The Sonar 4 PC application is specifically developed to do fish estimates in lakes.
Fish distribution during daytime, vertical beaming
The echogram below is recorded during daytime with vertical beaming, and shows schools of fish close to the bottom.
Fish distribution during nighttime, vertical beaming
This next echogram is recorded at night with vertical beaming.
Fish distribution during nighttime, horizontal beaming
This echogram is a typical example of fish distribution detected by horizontal beaming at night. Note that the range is now horizontal distance to the side of the boat and not depth.