Sea Mammal Research Unit (SMRU)
Data provided by the Sea Mammal Research Unit (SMRU)
If used, any layers should be acknowledged with
© Sea Mammal Research Unit
|Common/harbour seal (Phoca vitulina) - mean percentage at-sea population per 25 km (Carter et al 2022)||
These shapefiles are estimates of seal distribution on a 5 km x 5 km grid covering the maximum foraging range of seals from haulouts in the UK and Ireland.
For each cell, the confidence intervals represent the range of values within which, based onmthe underlying model, the true seal density is likely encompassed. The mean represents the a measure of the centre of this range.
The surfaces are provided as relative density.
For each cell, the value given represents the percentage of the UK and Ireland at-sea population (or SAC at-sea population for SAC-specific estimates) - i.e. excluding hauled-out animals - estimated to be present at any one time during the main foraging season (see below for information on temporal relevance).
Cells in the mean distribution surface sum to 100%. Thus, cell values can be summed across an area. For example, to estimate the total abundance of seals in an area of interest, it is possible to sum all cells in the mean distribution surface that fall within that area.
However, confidence interval estimates are provided on a cell-wise basis. Therefore, the sum of all cells in the lower confidence interval surface will be less than 100%, and the sum of all cells in the upper confidence interval surface will be greater than 100%. Cells in the confidence limit surfaces therefore CANNOT be summed across an area, and must be treated on a cell-by-cell basis. Summing these values across an area would give inflated confidence intervals.
Density estimates were spatially weighted using the most recent population count available per haulout. The majority of counts were from 2018, and 94.4% were from 2015 onwards.
Density estimates were predicted using environmental data from 2018. Thus, the density estimates represent relative seal density during the main foraging season in 2018.
CONSIDERATIONS AND EXCLUSIONS
Confidence intervals do not account for uncertainty relating to individual variation in habitat preference or temporal changes in abundance (e.g. throughout the day).
Estimates for the following areas should be treated with caution as they may contain a high degree of un-modelled uncertainty due to lack of recent telemetry data, or paucity of environmental data:
|Grey seal (Halichoerus grypus) pupping sites (OSCP)||
Grey seals (Halichoerus grypus) are present around the coast of Scotland in internationally import numbers. They breed on wave-exposed rocky coasts, sometimes on sand or shingle beaches at the foot of cliffs, often on relatively remote islands, with large groups of pregnant females returning to traditional breeding sites in the autumn. This data shows the breeding colonies currently listed with Sea Mammal Research Unit (SMRU).