Hornsea Project Four: Preliminary Environmental Information Report (PEIR) Volume 2, Chapter 4: Marine Mammals Prepared SMRU Consulting, 24th June 2019 Checked GoBe Consultants Ltd, 25th June 2019 Accepted David King, Ørsted, 26th July 2019 Approved Julian Carolan, Ørsted, 26th July 2019 Doc. no. A2.4 Version A Table of Contents 4.1 Introduction ...................................................................................................................................................9 4.2 Purpose ...........................................................................................................................................................9 4.3 Planning and Policy Context .................................................................................................................. 10 4.4 Consultation ............................................................................................................................................... 17 4.5 Study area ................................................................................................................................................... 19 4.6 Methodology to inform baseline ........................................................................................................... 19 4.7 Baseline environment ............................................................................................................................... 21 4.8 Project basis for assessment .................................................................................................................. 23 4.9 Maximum Design Scenario ...................................................................................................................... 25 4.10 Assessment methodology ...................................................................................................................... 31 4.11 Impact assessment ................................................................................................................................... 50 4.12 Cumulative effect assessment (CEA) ................................................................................................... 81 4.13 Transboundary effects ........................................................................................................................... 109 4.14 Inter-related effects ............................................................................................................................... 110 4.15 Conclusion and summary ...................................................................................................................... 111 4.16 References ................................................................................................................................................ 115 List of Tables Table 4.1: Summary of NPS EN-1 and EN-3 provision relevant to marine mammals. ............................ 13 Table 4.2: Summary of NPS EN-3 policy on decision making relevant to marine mammals. .............. 14 Table 4.3: Consultation Responses. .................................................................................................................... 17 Table 4.4: Key Sources of Marine Mammal Data............................................................................................. 20 Table 4.5: Summary of site-specific survey data. ............................................................................................ 21 Table 4.6: Marine mammal reference populations and densities taken forward for impact assessment for Hornsea Four. ............................................................................................................................... 22 Table 4.7: Favourable conservation status for each marine mammal species. ....................................... 23 Table 4.8: Marine mammal impact register - Impacts scoped out of assessment and justification. .. 24 Table 4.9: Relevant Marine Mammal Commitments. ..................................................................................... 24 Table 4.10: Maximum design scenario for impacts on marine mammals. ................................................. 26 Table 4.11: Definition of terms relating to receptor sensitivity. .................................................................. 31 Table 4.12: Definition of terms relating to magnitude of an impact. ......................................................... 31 Table 4.13: Hornsea Four piling most likely scenario ramp up. .................................................................... 34 Table 4.14: Hornsea Four maximum design scenario ramp up. .................................................................... 34 Table 4.15: Hornsea Four piling noise source levels (SPLpeak dB re 1 µPa @ 1 m, SELss dB re 1 µPa2s @ 1 m). .............................................................................................................................................................................. 34 Doc. no: A2.4 Version: A Page 2/130 Table 4.16: Summary of key marine mammal sensitivity assessments. .................................................... 45 Table 4.17: Impact area, maximum range and number of harbour porpoise predicted to experience PTS for the most likely piling scenarios............................................................................................................... 51 Table 4.18: Impact area, maximum range and number of minke whales predicted to experience PTS for the most likely piling scenarios. ...................................................................................................................... 52 Table 4.19: Non-impulsive PTS impact ranges for minke whales for the most likely piling scenarios. ....................................................................................................................................................................................... 53 Table 4.20: Impact area, maximum range and number of white-beaked dolphins predicted to experience PTS for the most likely piling scenarios. ........................................................................................ 54 Table 4.21: Impact area, maximum range and number of harbour and grey seals predicted to experience PTS for the most likely piling scenarios. ........................................................................................ 55 Table 4.22: Predicted PTS onset impact under the maximum design piling scenarios. ......................... 56 Table 4.23: Assessment of PTS onset for harbour porpoise and minke whales assuming a PTS onset impact range of either 2 or 5 km (northwest location). .................................................................................. 56 Table 4.24: Number of harbour porpoise predicted to experience potential behavioural disturbance for the most likely piling scenarios. ...................................................................................................................... 57 Table 4.25: Number of minke whales predicted to experience potential behavioural disturbance for the most likely piling scenarios. ............................................................................................................................ 59 Table 4.26: Number of white-beaked dolphins predicted to experience potential behavioural disturbance for the most likely piling scenarios................................................................................................ 60 Table 4.27: Number of harbour seals predicted to experience behavioural disturbance for the most likely piling scenarios. .............................................................................................................................................. 61 Table 4.28: Number of grey seals predicted to experience behavioural disturbance for the most likely piling scenarios. .............................................................................................................................................. 62 Table 4.29: Summary of predicted significance of impacts to marine mammals resulting from behavioural disturbance under the most likely scenario. .............................................................................. 64 Table 4.30: Number of animals predicted to experience behaviour disturbance under the maximum design piling scenarios. ............................................................................................................................................ 65 Table 4.31: Data from the UK Cetacean Strandings Investigation Programme (CSIP) on the number of cetacean strandings and identified causes of death. ................................................................................. 66 Table 4.32: Common prey species for each of the marine mammal receptors. Key species are in bold. ............................................................................................................................................................................. 70 Table 4.33: Estimated number of marine mammals potentially at risk of PTS during UXO clearance. ....................................................................................................................................................................................... 73 Table 4.34: Estimated number of marine mammals potentially at risk of disturbance during UXO clearance (assuming UXO is located at the centre of the array area). ...................................................... 75 Table 4.35: Description