Scientists have been using sonar and echo sounder systems on vessels for decades to conduct fish surveys.

Now Kongsberg Maritime has launched the new Simrad Autonomous EK system with cutting-edge technology to carry out continuous long-term, in-depth ecosystem monitoring of the subsea environment. The Simrad Autonomous EK system uses wideband echo sounding technology to discriminate between plankton and different fish species, producing high-quality, high-resolution scientific data.

The system is a fully autonomous echo sounder unit built using the same wideband technology as the latest high-precision, scientific wideband echo sounder, the Simrad EK80.

The battery technology and pressure-rated housing is already proven Kongsberg Maritime technology used in the oil and gas industry for decades, where duration and safety is of the highest concern.

Whereas traditionally multiple echo sounders working in parallel on different frequencies were needed to discriminate between marine species, the wideband technology used in the Simrad Autonomous EK system allows for transmission on frequencies from 35kHz to 500kHz, depending on the transducers used in the system setup. With four independent channels and internal multiplexing, a wide combination of split beam or up to eight single beam transducers can be interfaced to the system.

The Simrad Autonomous EK system contains features such as low-power consumption and an energy-saving sleep mode allowing it to be deployed on the seabed for more than a year operating autonomously with internal logging. A new mission planner software has been developed as part of the system, allowing for a pre-programmed customised mission plan. The wideband frequency sweep (chirp) in combination with advanced signal processing gives exceptionally good signal to noise ratio and range resolution. These new features assist scientists with ecosystem monitoring enabling them to identify species more accurately.

The Simrad Autonomous EK system has been developed in conjunction with leading marine institutes, with testing carried out by scientists in the Shelikof Strait in the Gulf of Alaska, where three unites were moored to the seafloor for a period of three months to record the passage of fish above them.

"The data looked beautiful," said Alex De Robertis, a biologist with the Alaska Fisheries Science Centre, the research branch of the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service in a recent NOAA press release.

Scientists from NOAA have used acoustics for many years to set sustainable catch limits for the Walleye Pollock, but until now this has been done from research vessels.

"This was a first trial. Usually we estimate how many fish we have by reading the acoustic echo off their backs. In this case, we’ll be reading the echo from their bellies."

Kongsberg Maritime Simrad Fish Research global sales manager Tonny Algrøy said: "The Autonomous EK system is entirely new in the Simrad product portfolio.

"The project in Alaska was a pre-release delivery and we are very proud that the very first long term deployment went so well.

"Ship-based surveys offer a snapshot of what’s happening in the water at the time the vessel is there, with the introduction of the Autonomous EK our users can now better understand what happens in between their surveys. The Autonomous EK records data of the same quality and in the same RAW format as the ship based Simrad EK80, allowing for easy comparison between data collected from multiple platforms."