3.14 Herring gull - Forth Islands SPA

Figure 3.49:
Projections of population sizes over a 50-year time-frame. Each plot represents a different impact scenario in terms of additional adult mortalities (starting at 0 i.e. unimpacted). Blue envelopes bound the central 95% of simulations, the dark central line the median.

Figure 3.49:  Projections of population sizes over a 50-year time-frame. Each plot represents a different impact scenario in terms of additional adult mortalities (starting at 0 i.e. unimpacted). Blue envelopes bound the central 95% of simulations, the dark central line the median.

Figure 3.50:
Ratio of impacted and unimpacted growth rates under a range of impact scenarios (additional adult mortalities – x-axis) i.e. 0.9 means a 10% decrease in the growth rate under the impact scenario. Figures are based on paired simulations for the impacted and unimpacted populations i.e. based on the same sampled population parameters. The bold lines represent the 50th percentile (median), dashed lines give the central 95% of simulated values (2.5% and 97.5% reference points).

Figure 3.50:  Ratio of impacted and unimpacted growth rates under a range of impact scenarios (additional adult mortalities – x-axis) i.e. 0.9 means a 10% decrease in the growth rate under the impact scenario. Figures are based on paired simulations for the impacted and unimpacted populations i.e. based on the same sampled population parameters. The bold lines represent the 50th percentile (median), dashed lines give the central 95% of simulated values (2.5% and 97.5% reference points).

Figure 3.51:
The ratio of the median impacted and median unimpacted population sizes from the simulations over a range of impact scenarios (additional adult deaths - x-axis) i.e. 0.5 means the median impacted population size is one-half the median unimpacted population size. Figures are based on paired simulations for the impacted and unimpacted populations i.e. based on the same sampled population parameters. The bold lines represent the 50th percentile (median), dashed lines give the central 95% of simulated values (2.5% and 97.5% reference points).

Figure 3.51:  The ratio of the median impacted and median unimpacted population sizes from the simulations over a range of impact scenarios (additional adult deaths - x-axis) i.e. 0.5 means the median impacted population size is one-half the median unimpacted population size. Figures are based on paired simulations for the impacted and unimpacted populations i.e. based on the same sampled population parameters. The bold lines represent the 50th percentile (median), dashed lines give the central 95% of simulated values (2.5% and 97.5% reference points).

Figure 3.52:
The median of the impacted population size as a centile of the unimpacted population size, under a range of impact scenarios (incremental additional adult deaths – x-axis). For example, 30 means the median (50th percentile) of the impacted projections sits at the 30th percentile of the unimpacted projections. Individual lines represent years post-construction (35 and 50 years).

Figure 3.52:  The median of the impacted population size as a centile of the unimpacted population size, under a range of impact scenarios (incremental additional adult deaths – x-axis). For example, 30 means the median (50th percentile) of the impacted projections sits at the 30th percentile of the unimpacted projections. Individual lines represent years post-construction (35 and 50 years).


Table 3.67: Growth rates of simulated populations under different impact scenarios for the 35 and 50 year post-construction projections. Reference points are 2.5%, 50% (median) and 97.5% of the distribution of simulated growth rates.

Projection year

Additional adult mortalities

Median growth rates

2.5 percentile of simulated growth rates

97.5 percentile of simulated growth rates

Median counterfactual of population size

Median counterfactual of growth rates

Centile of unimpacted matching 50th centile of unimpacted

2062

0

1.057

1.043

1.071

 

 

 

2062

10

1.056

1.042

1.070

0.966

0.999

45.5

2062

20

1.055

1.041

1.069

0.932

0.998

40.6

2062

30

1.054

1.040

1.068

0.900

0.997

35.9

2062

40

1.053

1.039

1.067

0.869

0.996

31.5

2062

50

1.052

1.038

1.066

0.839

0.995

27.6

2062

60

1.051

1.037

1.065

0.810

0.994

24.0

2062

70

1.050

1.036

1.064

0.782

0.993

19.9

2062

80

1.049

1.035

1.063

0.755

0.992

16.5

2077

0

1.057

1.045

1.069

 

 

 

2077

10

1.056

1.044

1.068

0.952

0.999

44.3

2077

20

1.055

1.043

1.067

0.906

0.998

38.7

2077

30

1.054

1.042

1.066

0.862

0.997

33.0

2077

40

1.053

1.041

1.065

0.820

0.996

27.6

2077

50

1.052

1.040

1.064

0.780

0.995

22.6

2077

60

1.051

1.039

1.063

0.742

0.994

18.6

2077

70

1.050

1.038

1.062

0.706

0.993

14.3

2077

80

1.049

1.037

1.061

0.672

0.992

11.1


Table 3.68: Relevant PVA metrics from models with impact scenarios for specific additional mortalities. Tabulated adult deaths account for the indicated sabbatical rate. Med. popn size = Median population size, Med. popn size (2062) 2.5/97.5% = are the central 95% of simulated population sizes.

Scenario

Sabb. Rate

Add. adult deaths

Add. immat. deaths

Med. popn size (2062)

Med. popn size (2062) 2.5%

Med. popn size (2062) 97.5%

Baseline

0.35

0.0000

0.000

116787.7

66486.4

200968.5

North Sea Consented developer approach

0.35

15.1680

4.040

113124.3

64375.7

194811.3

North Sea Consented Scoping Approach

0.35

22.1025

5.299

111572.6

63477.5

192205.9

(1) Project Alone: developer approach

0.35

10.1680

1.740

114459.4

65142.6

197071.3

(2) Project Alone: Scoping approach

0.35

17.1025

2.999

112887.5

64236.7

194433.9

 

Table 3.69: Relevant PVA metrics from models with impact scenarios for specific additional mortalities. Tabulated adult deaths account for the indicated sabbatical rate. Med. popn size = Median population size, Med. popn size (2077) 2.5/97.5% = are the central 95% of simulated population sizes.

Scenario

Sabb. Rate

Add. adult deaths

Add. immat. deaths

Med. popn size (2077)

Med. popn size (2077) 2.5%

Med. popn size (2077) 97.5%

Baseline

0.35

0.0000

0.000

269482.7

142561.8

499062.4

North Sea Consented developer approach

0.35

15.1680

4.040

257642.6

136231.9

477654.5

North Sea Consented Scoping Approach

0.35

22.1025

5.299

252678.4

133567.6

468664.1

(1) Project Alone: developer approach

0.35

10.1680

1.740

261932.8

138524.0

485464.6

(2) Project Alone: Scoping approach

0.35

17.1025

2.999

256883.6

135812.8

476344.6


Table 3.70: Relevant PVA metrics from models with impact scenarios for specific additional mortalities. Tabulated adult deaths account for the indicated sabbatical rate. Ann. med. GR = Annual median growth rate, Ann. med. GR,lower/upper CI are the 95% confidence bounds.

Scenario

Sabb. Rate

Add. adult deaths

Add. immat. deaths

Ann. med. GR (2062)

Ann. med. GR (2062) lower CI

Ann. med. GR (2062) upper CI

Ann. med. GR (2077)

Ann. med. GR (2077) lower CI

Ann. med. GR (2077) upper CI

Baseline

0.35

0.0000

0.000

1.057

1.043

1.071

1.057

1.045

1.069

North Sea Consented developer approach

0.35

15.1680

4.040

1.056

1.042

1.070

1.056

1.044

1.068

North Sea Consented Scoping Approach

0.35

22.1025

5.299

1.056

1.042

1.070

1.056

1.044

1.068

(1) Project Alone: developer approach

0.35

10.1680

1.740

1.057

1.043

1.071

1.057

1.045

1.069

(2) Project Alone: Scoping approach

0.35

17.1025

2.999

1.056

1.042

1.070

1.056

1.044

1.068

 

Table 3.71: Relevant PVA metrics from models with impact scenarios for specific additional mortalities. Tabulated adult deaths account for the indicated sabbatical rate. Med. cnterfact. popn size = Median counterfactual of population size, Med. cnterfact. GR = Median counterfactual of growth rates, Cent. unimp. match 50th cent. unimp. = Centile of unimpacted matching 50th centile of unimpacted.

Scenario

Sabb. Rate

Add. adult deaths

Add. immat. deaths

Med. cnterfact. popn size (2062)

Med. cnterfact. popn size (2077)

Med. cnterfact. GR (2062)

Med. cnterfact GR (2077)

North Sea Consented developer approach

0.35

15.1680

4.040

0.969

0.956

0.999

0.999

North Sea Consented Scoping Approach

0.35

22.1025

5.299

0.955

0.938

0.999

0.999

(1) Project Alone: developer approach

0.35

10.1680

1.740

0.980

0.972

0.999

0.999

(2) Project Alone: Scoping approach

0.35

17.1025

2.999

0.967

0.953

0.999

0.999