Echo Sounder – Shows Winter Herring Spawning

Echo Sounder – Shows Winter Herring Spawning 

An echo sounder measures the depth of water by measuring the time it takes for a pulse of energy to travel to the seabed and back. This short pulse of energy is transmitted vertically down from the boat. The time it takes for the energy to travel down and back determines the depth of water along with the speed of sound in the water. We use this information primarily for navigation purposes and obtaining depth for charting purpose.


Recently spotted near Gairloch in Wester Ross were some winter spawning Herring.We have been watching them coming closer to shore over the last few weeks.They are almost ready to spawn! This is very exciting because last March was the first recording of herring spawn in the Gairloch area for many years.

Echo Sounder


Our echo sounder shows Herring on the seabed in the area close to where we filmed the eggs last year.Normally when there are no fish the image would be similar to the right hand side of the photograph. The echo sounder tells us not only the depth of the water but also what the seabed is like – so when we fish for langoustines we would be looking for a deep muddy seabed, those looking for crabs etc would want a sandy seabed.


When fish are present it shows on the echo differently depending on the type of fish. The most experienced fishermen can tell the type of fish, how old they are and even if they are in spawn from the type of echo.

Wiped Out

Herring stock were wiped out during the 60s and 70s due to over fishing, prior to this Herring had been what had kept the fishing industry healthy. This rediscovery last March (2018) and their subsequent return in greater numbers is fantastic news. Creel fishermen are actually finding them in their creels, this has not been seen for a very long time!

Blue Planet

Blue Planet are on standby as we go live with our blog, as they want to capture footage of the spawning, the depositing, development and hatching of the eggs. As well as any predators! Cameramen have already arrived and the rest of the crew are expected to follow this week.

Gairloch on map


It is a fantastic opportunity that we are seeing signs of recovery here. It is hard to describe just how important these sightings are for the marine environment and fisheries in an area like this!

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