Duke Cherry Point PopUps 2005-2006 Bottlenose dolphin whistle presence

Duke University Marine Laboratory

Traditional marine mammal monitoring techniques, such as visual surveys, are not feasible under certain conditions, such as poor weather, darkness, and conflicts with other human activities. In such cases, alternative monitoring tools are required. We used autonomous acoustic recorders, designed by Cornell University, to monitor bottlenose dolphin (Tursiops truncatus) use of two ranges in Pamlico Sound, North Carolina, in which the United States Marine Corps conducts military training exercises. We deployed multiple units in the shallow waters of both ranges for more than a year. The recorders were programmed to sample at 12 kHz with a 12 kHz anti-aliasing filter. They were set on a duty cycle and of every hour, they recorded for either 10 or 30 consecutive minutes (bins of time referred to as “observation periods”). We analyzed the acoustic recordings using Raven 1.2.1 (Cornell Lab of Ornithology). We noted the presence or absence of dolphin whistles and clicks in each observation period to determine daily and seasonal patterns of dolphin occurrence in the two ranges. Vocalizing dolphins occurred frequently in both ranges throughout the year, with peaks of activity in June in both ranges and peaks in October, November, and December in one range. Vocalizing dolphins were detected more frequently in the late night and early morning hours than in the middle of the day and early night. We believe that such autonomous acoustic monitoring systems hold great promise for the management and mitigation of potentially adverse human activities on marine mammals.

The objective of this work was to address limitations of visual surveys in restricted ranges by conducting year-round monitoring of the presence of bottlenose dolphins in the Brant Island Shoal Bombing Target (BT-9) and the Piney Island Bombing Range (BT-11) using a passive acoustic monitoring system that could function during periods of darkness, poor weather, and on occasions when the ranges were in use.

Observation dates and times are in GMT. Observations represent presence of whistles during a given duration observation period, either 10 or 30 minutes. Number of observations is the number of observation periods with whistles present. Number of animals is unknown and should not be inferred: a single individual may be represented by multiple observations and likewise a single observation period may include recordings from multiple individuals.

Overview

This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downloadable online. Other attributes may be obtained upon provider's permission.

Attributes in dataset

Attribute (table column)	Description
oid	OBIS-SEAMAP Dataset ID
popupid
deployment	Deployment ID
station_id
latitude	Instrument Latitude
longitude	Instrument Longitude
obs_date	Start Date of observation GMT
obs_time	Start time of observation GMT
endday
endtime
sessionduration
sp_obs	Species observed
sp_tsn	Species TSN code
obs_count	Presence of dolphins whistles
recording_start_date_local	Start Date of observation Local time
recording_start_time_local	Start Time of observation Local time
recording_end_date_local	End Date of observation Local time
recording_end_time_local	End Time of observation Local time
gmt_diff	Time difference between GMT and Local
session_no
sound_files
popup_in_water
looked_at
dolphins_present	Presence or Absence of Dolphin whistles
fish_present	Presence or Absence of fish sounds
other	Presence or Absence of other noises
book_no_and_page_no_for_more_information