AN ULTRASONIC SALINITY TELEMETRY TRANSMITTER FOR USE ON FISH IN ESTUARIES

Tracking of fish by means of ultrasonic transmitters attached to individual fish has become an established technique in fisheries research. A salinity sensing transmitter for attachment to fish moving through estuaries is described. The salinity transducer is based on an ion-selective membrane cell, the output of which modulates the output pulse frequency of the transmitter. Transmission is at 77 kHz detectable by conventional sonic fish tracking equipment. First results from Atlantic salmon (Salmo salar L) indicate that these fish can experience rapid fluctuations in salinity during their movement into estuaries from the sea.