3.29 Lesser Black-backed gull - Coquet Island SPA

Figure 3.109:
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 3.109:  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 3.110:
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 3.110:  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 3.111:
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 3.111:  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 3.112:
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 3.112:  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 3.143: 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

0.974

0.949

1.001

 

 

 

2062

1

0.945

0.920

0.971

0.335

0.970

2.7

2062

2

0.914

0.884

0.941

0.102

0.939

0.0

2062

3

0.877

0.853

0.909

0.024

0.901

0.0

2062

4

0.844

0.824

0.871

0.006

0.866

0.0

2062

5

0.813

0.796

0.836

0.002

0.835

0.0

2077

0

0.974

0.951

0.997

 

 

 

2077

1

0.942

0.911

0.967

0.184

0.967

0.7

2077

2

0.900

0.878

0.932

0.019

0.925

0.0

2077

3

0.865

0.848

0.888

0.003

0.889

0.0

2077

4

0.834

0.820

0.854

0.000

0.857

0.0

2077

5

0.805

0.793

0.822

0.000

0.828

0.0

 

Table 3.144: 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

13.1

4.3

43.0

(1) Project Alone: developer approach

0.35

0.0078

0.001

13.0

4.2

42.7

(2) Project Alone: Scoping approach a

0.35

0.0104

0.002

13.0

4.2

42.5

 

Table 3.145: 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

8.6

2.2

35.4

(1) Project Alone: developer approach

0.35

0.0078

0.001

8.5

2.2

35.1

(2) Project Alone: Scoping approach a

0.35

0.0104

0.002

8.5

2.2

34.8

 

Table 3.146: 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. GRlower/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

0.974

0.949

1.001

0.974

0.951

0.997

(1) Project Alone: developer approach

0.35

0.0078

0.001

0.974

0.949

1.001

0.973

0.951

0.997

(2) Project Alone: Scoping approach a

0.35

0.0104

0.002

0.974

0.949

1.001

0.973

0.951

0.997

 

Table 3.147: 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)

(1) Project Alone: developer approach

0.35

0.0078

0.001

0.996

0.996

1

1

(2) Project Alone: Scoping approach a

0.35

0.0104

0.002

0.995

0.994

1

1