The new Notus Echo real-time monitoring system finally provides an answer to one of the main questions frequently asked by the skipper of any shellfish trawler: “Where am I catching shellfish on my tow?”

The real-time monitoring system detects the sound of shellfish hitting a sorting grate or pickup device in a trawl. This information is transmitted to the

Screen display of trawl sensors and Echo on Mistasea.

Screen display of trawl sensors and Echo on Mistasea.

vessel in real time. Systems are being supplied in a stand-alone format, or with optional trawl sensors.

Conventional sounders cannot detect shellfish as they have no swim bladder, unlike fish.

The Notus Echo consists of a sensor and microphone. The microphone listens for the sound of shellfish hitting the trawl. Sound increases and decreases with the amount of shellfish. The sensor then transmits this information back to the vessel. A hydrophone is towed alongside or mounted in the hull. This is connected to a command unit in the wheelhouse that displays information on a computer. The Echo also monitors grate angle and seawater temperature.

The results have been astounding for increasing catch. A skipper can detect exactly where he is catching shellfish on a three- to four-hour tow. This previously unavailable information enables him to turn around and hit the same ‘hot spot’ again.

Echo installed on a trawl grate.

Echo installed on a trawl grate.

Feedback from skippers included the following:

  • Skipper Jimmy Burns, Galway Bay: “It’s awesome! Worked right out of the box. I can see if I’m catching 250kg/hr or 1,000kg/hr.”
  • Skipper Ben Downs, Pacific Dove: “Seeing where I am catching shellfish changed our fishing operation. We would not want to fish without it.”

Many vessels have added door sensors to their Echo system. On a double-rig trawler, this means monitoring the door spread on each trawl, trawl wire lengths, and door angle. These geometry sensors enable the skipper to fine-tune his operation for optimal fishing.

Basically, you can locate shellfish with the Echo and ensure maximum catch with optimal spread, trawl wire lengths and door angle.


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