15 Apr 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes from tape: "Unscheduled; Time 2028 Zulu 15Mar1974." Notes from analysis log: "Good signals. Cassette "Special" side up - rewind. Ambient level low, no ship traffic sounds. Humpback: Pos.; No. Calling: 1; No. Full Calls: 1+; Need for further analysis: Yes. Notes: Starts off with good signal level, continuation of the first special recording with approximately 14 min lost time 'cassette' change. Calls are 14-15 min duration herre. Minke: Pos.; No. Heard: 1? Need for further analysis: No. Notes: At 042 a thump train mod level, again at 425, 483, stronger, at 666 a moderate train."
[Notes from analysis log for all tapes in the GRANDTURKS series: "Six half-hour background recording samples on selected days for a period of 53 days... to detect the arrival and departure of the Humpback whales (via sounds) for the season in the Caribbean Sea, Mouchier, Navidad and Silver Banks...There are indications that recordings used a 420Hz Low Pass Filter. Recording equipment used was a Realistic model CTR-19. Cassette recorder operating on 110VAC, Freq 60-10,000Ha.. The Realistic recorder is poor recording frequencies below 60Hz as evidenced by spec sheet and sonograms. There is 120 & 180Hz electrical interference 'splatter' on some tapes. In certain cases when the ambient is low, the gain of the systems are raised hence we have heavy interference masking wanted signals. This could be caused by a fluorescent light fixture near the recording system? I doubt that it is in the hydrophone pre-amp network." See analysis log for more details.] SEAOCEAN