GREEN LINE
STM Products

Selective protection for set nets and longlines

The STM Products Green Line is the solution for operators working long nets in areas with variable cetacean presence. The electronics activate on immersion, but ultrasound emission only engages when the system detects dolphin echolocation clicks nearby. In the absence of cetaceans, the pinger remains completely silent. In the operational context of longlines and large-scale drift nets, where recharging is not always practical, this selective logic makes a real difference to battery life and the organisation of work at sea.

Once triggered, emissions are randomised in frequency and intensity across the 5–500 kHz range, with output up to 165 dB. The continuous randomisation of acoustic parameters makes dolphin habituation as difficult as possible over time, keeping effectiveness high even after weeks of continuous use.

Main
technical features

Green Line pingers integrate the technological core shared by the entire STM Products range: 32-bit microprocessor, sealed internal NiMH batteries rechargeable for up to 1,000 cycles, and automatic activation on immersion. Operating depth ranges from 10 to 400 m. To prevent devices from triggering one another, the recommended spacing between two DiD 02 units is 800–1,000 m, greater than that of passive models. The precision of on-detection selective emission compensates for the lower installation density, delivering a targeted and immediate response.

The Green Line model

DiD 02

For set nets, drift nets and longlines

The DiD 02 is developed specifically for the gear types where dolphins interact most persistently: long fixed or drift set nets and longlines. It is installed along the net at one unit every 800–1,000 m, creating a distributed coverage that responds selectively only to actual cetacean presence. This intervention logic makes it particularly well suited to extended fishing trips, where recharging is not always possible and every battery cycle must be used as efficiently as possible. Compared to passive deterrents, the DiD 02 delivers the same effectiveness in the presence of dolphins, with a significantly lower overall acoustic impact on the marine ecosystem.

Accessories for the STM Products Green Line

The same accessories available across the entire STM range are compatible with Green Line pingers: the VOLTester for quick battery checks before each deployment, the STM single charger, and the MBC4 multi-charger for recharging up to four devices simultaneously. A practical logistics solution for those who work at sea every day and cannot afford unnecessary downtime.