ME harbor and gray seals time series

University of Maine

Dataset credit

NOAA Northeast Fisheries Science Center
James Gilbert, University of Maine
Wendy Dow, Duke University


Primary contact James Gilbert Department of Wildlife Ecology, University of Maine
Data entry Ei Fujioka Duke University



Seal populations in the northwest Atlantic are thriving, yet few grant dollars go to seal projects in the northeast region. According to many researchers and managers in the region, the healthy state of stocks is exactly why we should be studying seals. Seal and human activities along the coast often result in conflicts, which will undoubtedly increase as the population and range of both seals and humans increase. The east coast of the United States lacks a management plan for seals. A problem that seriously impedes management is that managers do not know where the seals are and more specifically, where haul-out sites are. This atlas is designed to aid managers and researchers in the management and conservation of seals in the northwest Atlantic. The atlas and the data used to create the atlas can be accessed through OBIS-SEAMAP.


The purpose of this dataset and atlas is to provide data from a series of aerial surveys conducted between 1981 and 2001 of harbor and gray seal haul-out sites in Maine.

Supplemental information

The original data were transposed so that each record represents seals abundance at a single ledge on a single day. As this dataset is a time-series, an appropriate way to represent it is to show it with time-series charts by region. Currently, OBIS-SEAMAP lets you see it on Google Earth with the charts. Not all seasons are represented in this dataset, and distributions of seals may be different in other seasons. Lack of a count for a ledge on a particular date does not necessarily mean the ledge was not observed.


Gilbert, J.R., G.T. Waring, K.M. Wynne, and N. Guldager. 2005. Changes in abundance of harbor seals in Maine, 1981-2001. Marine Mammal Science. 21(3):519-535.



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
datasetDataset ID
linenoLine number
ledgeLedge name
regionLedge region
longitudeLongitude in decimal degrees
latitudeLatitude in decimal degrees
survey_idSurvey ID
dateDate of the observation
spcodeSpecies code
commonCommon name
scientificScientific name
tsnITIS Taxonomic Serial Number added by OBIS-SEAMAP
lifestageLife stage
countThe number of animals
excludedFor internal use
geomGeometry field added by OBIS-SEAMAP
oidUnique ID number (generated by OBIS-SEAMAP)
Marine mammals6,973
Sea turtles0
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin1981-03-15
Date, End2001-06-04
Temporal prec.111000
Latitude42.97 - 44.93
Longitude-70.70 - -66.98
Coord. prec.6 decimal digits
Data typeAnimal sighting
Traveled (km)0
Contr. through
Sharing policy CC-BY-NC (Minimum)
Shared with OBIS
GBIF (via DOI)
See metadata in static HTML
See metadata in FGDC XML
See download history / statistics