Virginia and Maryland Sea Turtle Research and Conservation Initiative Aerial Survey Sightings, May 2011 through July 2013

Virginia Aquarium & Marine Science Center

Dataset credit

Virginia Aquarium Foundation - Susan G. Barco & Gwen G. Lockhart
Riverhead Foundation for Marine Research & Preservation - Robert A. DiGiovanni Jr. & Allison M. DePerte


Primary contact Sue Barco Virginia Aquarium Foundation-Research
Data entry Ei Fujioka Duke University


Barco, S. 2014. Virginia and Maryland Sea Turtle Research and Conservation Initiative Aerial Survey Sightings, May 2011 through July 2013. Data downloaded from OBIS-SEAMAP ( on yyyy-mm-dd.


The data provided were collected as part of the the Virginia and Maryland Sea Turtle Research & Conservation Initiative - funded by the National Marine Fisheries Service Species Recovery Grants program No. NA09NMF4720033.


Previous sea turtle abundance estimates reported in the Virginia portion of the Chesapeake Bay where developed using aerial surveys without correcting for seasonal differences and availability bias. More recent surveys yielded estimates of availability throughout the turtles' residency periods using radio transmitters and satellite telemetry. These estimates where significantly different then previous surveys and changed over time. This project was conducted in order to quantify turtles surfacing time for the purpose of calculating seasonal and annual differences in availability, conduct aerial surveys in a manner that will allow for the calculation of perception bias, and compare estimates generated during previous projects.

Supplemental information

Aerial surveys were conducted along the coastal waters and bays of Virginia and Maryland. This project is broken into two survey periods. The survey platform was a De Havilland twin otter DHC‐6 modified for observational research. The aircraft was configured so as to have two forward observers and a data recorder on their own communication system and have a second team consisting of a belly observer and one additional observer (either port or starboard) along with a data recorder. The separation of the communications systems enables the two teams to function independently thereby functioning as two individual surveys. Groups of sea turles, marine mammals, and other marine mammals were recorded. This method was developed in order to calculate a perception bias using mark recapture techniques. This dataset is the filtered version – meaning all the duplicate sightings have been removed. All records are marked as observed by only team one, only team two, or by both. There is only one record for each sighting even if the animal was sighted by both teams. The raw dataset, with all sighting from both teams, is available by request from the Virginia Aquarium & Marine Science Foundation.




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
oidUnique ID number (generated by OBIS-SEAMAP)
objectidRow ID assigned by VAQF ArcGIS
obs_countBest estimate of group size
obs_dateDate of sighting
obs_timeTime of sighting in local time zone
sp_obsSpecies name recorded
sp_tsnTaxonomic Serial Number added by OBIS-SEAMAP
strataSurvey block: A to E
surveyNumber of survey
transectRecorded transect line: Series/LineNumber
seriesSet of lines used during survey
linenumberNumber of transect line
teamObserver team: 1 = front, 2 = rear, 3 = both
lineLine ID
sightingnumberSighting number as recorded
duplicatesightingnumberRecorded sighting number of duplicate sighting
obsInitials of observer
angsideSide of sighting: R = right, L = left (only recorded if ObsPosition = C)
dist_mPerpendicular distance (meters)
swimdirSwim direction
obspositionPosition of observer in plane: L = left, R = right, C = centre (belly window)
latitudeLatitude in decimal degrees
longitudeLongitude in decimal degrees
speedSpeed of plane
directionDirection of plane (degrees)
altitudeAltitude of plane (meters)
beaufortBeaufort sea state
turbidityTurbidity: 0 = clear, 1 = moderately clear, 2 = turbid, 9 = unknown
ccCloud cover: 0 = no clouds, 1-99 = %age of cloud cover
glarefromGlare from front of plane
glaretoGlare to front of plane
glareseveritySeverity of glare: 0 = none, 1 = slight, 2 = moderate, 3 = excessive
qualitySubjective quality: 1 = excellent, 2 = good, 3 = moderate, 4 = fair, 5 = poor, 0 = over land or off effort
transectidTransect identifier based on Survey-LineNumber
sightingidUnique identifier of sighting: Survey-Team-SightingNum
dupidUnique identifier of duplicate sighting
speciesgroupSpecies group of sighting
transect_labelTransectLabel Transect identifier based on Season-Year-LineNumber
angAngle from horizon
newteamObserver team: 1 = front, 2 = rear, 3 = both
transectetidTransect identifier based on TransectYearMonthDay
sst_cSea surface temperature (Celsius)
sst_fSea surface temperature (Fahrenheit)
geomGeometry field added by OBIS-SEAMAP
Marine mammals1,110
Sea turtles4,354
Rays and sharks30
Other species38
Non spatial0
Non species0
Date, Begin2011-05-22
Date, End2013-07-31
Temporal prec.111111
Latitude36.58 - 38.52
Longitude-76.40 - -74.40
Coord. prec.5 decimal digits
Data typeAnimal sighting
Traveled (km)0
Contr. through
Sharing policy CC-BY-NC (Minimum)
Shared with OBIS
GBIF (via DOI)
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See metadata in FGDC XML
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