Population trends and abundance of seals - Ringed seal 2018 (HOLAS 2)
This core indicator evaluates the status of the marine environment based on population trends and abundance of the three species of seals that occur in the Baltic Sea. This dataset is for Ringed seal. Good status is achieved for each species when the abundance of seals in each management unit is at least 10,000 individuals and the species-specific growth rate is achieved. Harbour seals in the southwestern Baltic and the Kattegat form a metapopulation, where subpopulations are genetically connected. The combined sizes of the subpopulations are here used to evaluate the Limit Reference level (LRL).
The status evaluation is presented separately for the three seal species. The grey seal in the Baltic proper is evaluated as a single unit, whereas the Kattegat grey seals are evaluated separately. The status of ringed seals is evaluated for two management units. The status of harbour seals is evaluated for three management units.
Ringed seal dataset displays the result of the indicator in HELCOM Assessment Scale 2 (Division of the Baltic Sea into 17 sub-basins).
Attribute information:
"HELCOM_ID" = HELCOM ID of the scale 2 assessment unit
"level_2" = Name of the HELCOM scale 2 assessment unit
"Assessment" = Name of assessment unity area considered
"Area (km2)" = Area of the HELCOM scale 2 assessment unit
"Status" = Status of the indicator (“Achieve”, “Fail” or “Not assessed”)
"AULEVEL" = Assessment unit level used for the indicator
"Unit of indicator" = Unit of indicator (Abundance - Harbour seal / % decrease)
"Threshold value" = Threshold value of the indicator
"Indicator value" = Indicator value
"Info" = Additional information
"ConfA" = Confidence of classification
"ConfT" = Temporal confidence of classification
"ConfS" = Spatial confidence of classification
"ConfM" = Methodological confidence of classification
Simple
- Date (Publication)
- 2018-06-28
- Unique resource identifier
- https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/56179382-8f1e-4418-8c2c-faa736549810
-
GEMET - INSPIRE themes, version 1.0
-
-
Habitats and biotopes
-
-
GEMET
-
-
ecological abundance
-
marine mammal
-
population trend
-
- Keywords
-
-
MADS
-
HOLAS2 2018 Core indicator
-
Core indicator
-
- Use constraints
- Other restrictions
- Other constraints
-
Use constraints: The data and resulting data products (tables, figures and maps) available on the indicator web page can be used freely given that the source is cited. The indicator should be cited as following: HELCOM (2018) Population trends and abundance of seals - Ringed seal. HELCOM core indicator report. Online. [Date Viewed], [Web link].
- Access constraints
- Other restrictions
- Other constraints
- Access constraints: No limitations on public access.
- Spatial representation type
- Vector
- Metadata language
- English
- Topic category
-
- Environment
- Begin date
- 2011-01-01
- End date
- 2016-12-31
- Unique resource identifier
- EPSG:3035
- Distribution format
-
-
ESRI Shapefile
(
1.0
)
-
ESRI Shapefile
(
1.0
)
- OnLine resource
- Download dataset ( WWW:LINK-1.0-http--link )
- OnLine resource
- Open in Map Viewer ( WWW:LINK-1.0-http--link )
- Hierarchy level
- Dataset
Conformance result
- Date (Publication)
- 2010-12-08
- Statement
-
The indicator is based on line transect surveys of hauled out ringed seals on ice during the moulting period in the latter half of April. Such surveys have been carried out annually in the Bothnian Bay. Only sporadic surveys have been carried out in the Archipelago Sea , the Gulf of Finland and Estonian coastal waters due to limited or no sea ice. Surveys are carried out from high-winged aircrafts, where all seals within the transect are photographed for later enumeration on the photos. A minumum of 13% of the ice area is covered. Greater effort only marginally reduce variances. Surveys should be carried out during similar conditions each year to get compatible results. In two years (2014 and 2015) ice conditions deteriorated early in the Bothnian Bay, which is why these years have to be treated separately in trend analyses. The reason why much higher numbers hauled out in 2014 and 2015 was that subadult animals that normally are chased away by the adults entered into the breeding ice when the social structure of the habitat collapsed. Nevertheless, these high numbers show that numbers of seals in the Bothnian Bay amount to about 20 000 seals . The criteria for GES are that numbers of seals must exceed 10 000 animals and that the population growth rate must exceed 7% per year. Survey data are available from the Gulf of Finland and Estonian coastal waters from 1996. In the Gulf of Finland numbers of seals have decreased from 300 in 1996 to 100 in 2015. For Estonia no increase is seen since 1996, but possibly a decrease.
The calculations have been carried out by Lead Country Sweden based on survey data. For the Archipelago Sea, the Gulf of Finland and Estonian coastal waters indicator reference is given to data published in the references provided in the Core indicator report (see link below).
Additional information:
http://www.helcom.fi/baltic-sea-trends/indicators/population-trends-and-abundance-of-seals/
- File identifier
- 56179382-8f1e-4418-8c2c-faa736549810 XML
- Metadata language
- English
- Character set
- UTF8
- Hierarchy level
- Dataset
- Date stamp
- 2023-03-17T05:49:07