Terapon theraps chorus observed in shallow water environment in the southeastern Arabian Sea

Long term acoustic measurements have been obtained from shallow water environment in the southeastern Arabian Sea (SEAS) off Cochin during the period of January-May 2011. This is the first time record in Indian seas. Based on the spectrogram analysis, call type is found to be chorus, where many fishes called en masse. The chorus produced by the fish 'Terapon theraps' sounded like 'trumpet' and displayed unique call characteristics throughout the period. They produced daily patterns with the highest activity level before dawn and after dusk. Numbers of trumpet chorus were maximal at the beginning of the January to end of March, but ceased down by the May. The fish chorus for this site reached similar to 30 dB above ambient noise level at the frequency of their spectral maximum. This chorus is believed to be associated with spawning. Visual surveys are conducted separately to confirm the presence of Terapon theraps contiguous to SEAS.