3.7 Gannet - Hermaness, Saxa Vord and Valla Field SPA

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 3.21: 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 3.22:
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 3.22: 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 3.23:
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 3.23: 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).

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 3.24: 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 3.32: 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	1.038	1.023	1.051
2062	10	1.038	1.023	1.050	0.992	1.000	48.7
2062	20	1.038	1.023	1.050	0.984	1.000	47.6
2062	30	1.037	1.022	1.050	0.977	0.999	46.5
2062	40	1.037	1.022	1.050	0.969	0.999	45.5
2062	50	1.037	1.022	1.049	0.961	0.999	44.4
2062	60	1.037	1.022	1.049	0.954	0.999	43.2
2062	70	1.036	1.022	1.049	0.946	0.998	42.3
2062	80	1.036	1.021	1.049	0.939	0.998	41.1
2062	90	1.036	1.021	1.049	0.931	0.998	39.9
2062	100	1.036	1.021	1.048	0.924	0.998	38.7
2062	110	1.036	1.021	1.048	0.917	0.998	37.9
2062	120	1.035	1.020	1.048	0.910	0.997	36.9
2062	130	1.035	1.020	1.048	0.902	0.997	35.9
2062	140	1.035	1.020	1.047	0.895	0.997	35.0
2062	150	1.035	1.020	1.047	0.888	0.997	33.8
2077	0	1.038	1.025	1.048
2077	10	1.038	1.025	1.048	0.989	1.000	48.8
2077	20	1.037	1.025	1.048	0.978	1.000	47.4
2077	30	1.037	1.025	1.048	0.967	0.999	46.0
2077	40	1.037	1.024	1.047	0.956	0.999	44.4
2077	50	1.037	1.024	1.047	0.946	0.999	43.2
2077	60	1.036	1.024	1.047	0.935	0.999	41.9
2077	70	1.036	1.024	1.047	0.925	0.998	40.7
2077	80	1.036	1.023	1.046	0.914	0.998	39.5
2077	90	1.036	1.023	1.046	0.904	0.998	38.3
2077	100	1.036	1.023	1.046	0.894	0.998	36.9
2077	110	1.035	1.023	1.046	0.884	0.998	35.7
2077	120	1.035	1.022	1.046	0.874	0.997	34.4
2077	130	1.035	1.022	1.045	0.864	0.997	33.4
2077	140	1.035	1.022	1.045	0.855	0.997	32.0
2077	150	1.034	1.022	1.045	0.845	0.997	30.8

Table 3.33: 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	0.1	0.00	0.00	304501.0	169277.5	510147.8
North Sea Consented developer approach	0.1	75.30	60.07	286723.9	159231.1	480445.2
North Sea Consented Scoping Approach a	0.1	76.81	60.11	286492.1	159103.0	480063.0
North Sea Consented Scoping Approach b	0.1	104.20	82.26	280252.3	155580.2	469640.0

Table 3.34: 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	0.1	0.00	0.00	533584.4	269654.1	950432.1
North Sea Consented developer approach	0.1	75.30	60.07	489847.2	247298.7	873090.5
North Sea Consented Scoping Approach a	0.1	76.81	60.11	489294.0	247024.7	872110.2
North Sea Consented Scoping Approach b	0.1	104.20	82.26	474216.8	239342.0	845438.6

Table 3.35: 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	0.1	0.00	0.00	1.038	1.023	1.051	1.038	1.025	1.048
North Sea Consented developer approach	0.1	75.30	60.07	1.036	1.021	1.049	1.036	1.023	1.046
North Sea Consented Scoping Approach a	0.1	76.81	60.11	1.036	1.021	1.049	1.036	1.023	1.046
North Sea Consented Scoping Approach b	0.1	104.20	82.26	1.036	1.021	1.048	1.035	1.023	1.046

Table 3.36: 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	0.1	75.30	60.07	0.942	0.918	0.998	0.998
North Sea Consented Scoping Approach a	0.1	76.81	60.11	0.941	0.917	0.998	0.998
North Sea Consented Scoping Approach b	0.1	104.20	82.26	0.920	0.889	0.998	0.998

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