3.4. Grey Seal

Results for the maximum temporal scenario indicate no difference in the population trajectory of grey seal between the unimpacted population and impacted populations ( Figure 3.12 Open ▸ ). At all time points there was no difference in the mean size of the impacted and unimpacted populations ( Table 3.12 Open ▸ ), including at all six-year Habitats Directive reporting periods, and at the end of the 25-year model simulation.

Both the median and mean counterfactual for scenario MW-01 remained at 1.0000 throughout the 26-year simulation ( Table 3.12 Open ▸ ), indicating no discernible difference in the ratio of the disturbed to un-disturbed populations and no potential for a long term population-level effect from this piling scenario upon grey seal.

Results for the maximum temporal scenario indicate no difference in the population trajectory of grey seal between the unimpacted population and impacted population ( Figure 3.13 Open ▸ ). At all time points there was no difference in the mean size of the impacted and unimpacted populations ( Table 3.13 Open ▸ ) including at all six-year Habitats Directive reporting periods, and at the end of the 25-year model simulation.

Both the median and mean counterfactual for scenario MW-01 remained at 1.0000 throughout the 26-year simulation ( Table 3.13 Open ▸ ), indicating no discernible difference in the ratio of the disturbed to un-disturbed populations and no potential for a long term population-level effect from this piling scenario upon grey seal.

For scenario GS-C1, in which a total of 306 days of piling were modelled at the Array alongside a total of 112 piling days at Berwick Bank, these results indicate no difference in the simulated trajectories of grey seal between the unimpacted population and impacted population ( Figure 3.14 Open ▸ ). This corresponds to no difference in the size of the impacted population at time point 26, compared to the un-impacted population ( Table 3.14 Open ▸ [3]).
At all time points in the 26-year model simulation there is no difference in the size of the impacted population, compared to the unimpacted population. When compared to the equivalent time point from scenario GS-01 (i.e. three years into the maximum temporal scenario for the Array alone: section 3.2.1), this is also no difference between populations.
Both the median and mean counterfactual of population size for cumulative scenario GS-C1 was 1.0000 throughout the 26-year simulation. Therefore, given that the differences in disturbed to undisturbed populations equates to a ratio of 1 there is not considered to be a potential for a long term population-level effect from this cumulative piling scenario upon grey seal.