Use constraints: Data can be used freely given that the source is cited as "HELCOM HOLAS II Dataset: Grey seal distribution (2018)".

Data source:

Species Information sheet related to HELCOM Red list assessment available at http://www.helcom.fi/Red%20List%20Species%20Information%20Sheet/HELCOM%20Red%20List%20Halichoerus%20grypus.pdf

Data quality:

The map is based on expert judgement and gives a rough estimate on the distribution of harbour seals in the Baltic Sea.

Attribute information:

Raster representing abundance class with following values

1 = Common occurrence and reproduction

0.75 = Regular occurrence, no regular reproduction

0.5 = Rare occurrence, no regular reproduction

0 = Very rare or no occurrence

The classes are defined as

Common occurrence and reproduction - The area covers the core moulting areas, which mostly are important breeding areas for the species as well.

Regular occurrence, no regular reproduction - Outside of the breeding and moulting seasons the species uses the area regularly for foraging and traveling, but no regular breeding occurs.

Rare occurrence, no regular reproduction - The species does not regularly use the area for foraging or traveling and no breeding occurs, but has on rare occasions been observed in the area.

Very rare or no occurrence - The breeding and moulting areas of the species are relatively far compared to the travelling behavior of the species, making random observations or any other sign of occurrence in this area very rare or non-existent.

Spatial resolution:

Baltic Sea sub-basins.

Time period and temporal resolution:

Original map produced in 2013. Revised for HOLASII in 2016-2017. Revised for the HOLASII update in 2017-2018.