Equipment carrier Triaxus

Since May 2010, the three Thünen Fisheries Institutes have had a state-of-the-art instrument platform for their fisheries biology research. The so-called "Triaxus" (MacArtney A/S) is towed behind the ship at up to 10kn (around 18km/h) and can steer itself vertically and horizontally through the water column, automatically stabilising the horizontal position of the instrument. We use the Triaxus

• at a constant depth (e.g. to measure water parameters at a depth over a long distance - important e.g. for the detection of marine fronts)
• at a certain distance from the bottom (e.g. to take sonar or video images of the seabed)
• for ascending and descending in given depth ranges in order to record parameters of the water column on as small a scale as possible while the ship is moving. It is also possible to move out to the side in order to sample a water body near the surface that has not been influenced by the ship ahead.

Currently, the following external sensors are used on the Triaxus:

• Edgetech MP2200 230/530 MHz sidescan sonar.
• 2 hydrography probes SBE 911plus (incl. oxygen sensor)
• ODIM/Brooke Ocean Laser Optical Particle Counter (LOPC). The device measures the particle distribution (frequency and size) in the water column with the help of a laser curtain.
• Camera system consisting of pan/tilt head (ROS PT-10), SW low-light camera (ROS Navigator) and 2xLED spotlight (ROS MV-LED)

The Thünen Institute of Baltic Sea Fisheries is responsible for the maintenance and deployment of this system in close cooperation with the Thünen Institute of Sea Fisheries.