Simrad Echo Sounder
Ullapool Museum

Echo-sound technology like this Simrad echo sounder cleverly works to locate objects under the sea. By sending out sound waves and recording the time it takes for the echo to return, the echo sounder is able to detect the depth of the sea in a range of locations. It operates on the principle that sound travels through water at a constant speed.

This echo sounder was installed on the ‘Fram’, a prawn creel boat based in Loch Broom. It was invaluable for identifying the type of seabed beneath them, as well as deciding where to drop their creel pots. The peaks and dips of the graph show the uneven seabed in the waters around the Coigach Peninsula.

Creel pots were baited with salted fish to lure the prawns into the creel from their burrows in the muddy seabed. The creels were then hauled up, emptied and rebaited before being returned to the seabed.

Previously, successful fishing depended on the wealth of knowledge acquired by generations of fishermen, experienced in the best places to fish at various times of the year. Echo sounding technology enabled a more targeted and efficient operation but unfortunately this increased the risk of overfishing. Today, regulations are an important part of protecting our marine environment to prevent overfishing and the risk of extinction of our critical marine culture.