27 Feb 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes on tape: "Time1923 Zulu." [MLNS notes: low level thumps throughout, with several louder single thumps, or pulses, interspersed.] Notes from analysis log: "Cassette number side up - rewind. ambient level moderate, distant ship traffic. Humpback: Neg. Minke: Pos.; No. Heard: 2 or 3; No. Trains: 17+. Need for further analysis: Yes (132) + 580-585 hear both for a short period. Notes: At 018 have strong thump train; at 049 have weak thump train - At 132 a strong thump train, at 204 a start to a broken thump train - at 255 a part of a thump train, at 305 a strong train, at 433 a moderate level thump train. At 458 the strong train, again at 558, a short broken-off train. At 580 + 585 hear both; again at 600 hear both for a short period. At 642 a strong one 662 a short train, at 685 again, at 714, at 759 a weak one, a strong one 779, again at 796."
[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