9. Fish and Shellfish Ecology
9.1. Introduction
1. This chapter of the Array Environmental Impact Assessment (EIA) Report presents the assessment of the likely significant effects (LSE1) (as per the EIA Regulations) on fish and shellfish ecology as a result of the Ossian Array which is the subject of this application (hereafter referred to as “the Array”). Specifically, this chapter assesses the LSE1 of the Array on fish and shellfish ecology during the construction, operation and maintenance, and decommissioning phases.
2. In this Array EIA Report, LSE1 refers to the term used in the EIA Regulations. The accompanying Report to Inform Appropriate Assessment (RIAA) for the Array uses the term as defined by the Habitats Regulations Appraisal (HRA) Regulations.
3. The following technical chapters and appendices also inform the assessment presented in this chapter:
- volume 2, chapter 7: Physical Processes;
- volume 3, appendix 7.1: Physical Processes Technical Report;
- volume 2, chapter 8: Benthic Subtidal Ecology;
- volume 3, appendix 8.1: Benthic Subtidal Ecology Technical Report;
- volume 3, appendix 9.1: Fish and Shellfish Ecology Technical Report;
- volume 2, chapter 10: Marine Mammals;
- volume 3, appendix 10.1: Underwater Noise Technical Report;
- volume 2, chapter 11: Offshore Ornithology; and
- volume 3, appendix 12.1: Commercial Fisheries Technical Report;
4. This chapter summarises information contained within volume 3, appendix 9.1.
9.2. Purpose of the Chapter
6. The purpose of this fish and shellfish Array EIA Report chapter is to:
- present the existing environmental baseline established from desk studies, site-specific surveys, numerical modelling studies consultation with stakeholders;
- identify any assumptions and limitations encountered in compiling the environmental information;
- present the environmental impacts on fish and shellfish ecology arising from the Array and reach a conclusion on the LSE1 on fish and shellfish ecology, based on the information gathered and the analysis and assessments undertaken; and
- highlight any necessary monitoring and/or mitigation measures which are recommended to prevent, minimise, reduce or offset the likely significant adverse environmental effects of the Array on fish and shellfish ecology.
9.3. Study Area
7. As fish and shellfish are spatially and temporally variable, a broad fish and shellfish ecology study area has been defined for the purposes of baseline characterisation.
8. The fish and shellfish ecology study area has been reduced compared to the fish and shellfish ecology study area presented in the Array EIA Scoping Report (Ossian OWFL, 2023). Consultation feedback received from Marine Directorate - Licensing Operations Team (MD-LOT) in 2023 advised that though they were “…broadly content with the proposed fish and shellfish ecology study area” presented in the Array EIA Scoping Report, “identifying a smaller study area using the recommended methods detailed in the NatureScot representation” was recommended. NatureScot advised in their Array EIA Scoping Report response in relation to the fish and shellfish study area that “…this is a very large area. The Applicant may wish to consider a smaller study area based on either International Council for the Exploration of the Sea (ICES) rectangles or modelled subsea noise and/or Suspended Sediment Concentrations (SSC) data, whichever extend furthest from the site” (MD-LOT, 2023).
9. Although the fish and shellfish ecology study area presented in the Array EIA Scoping Report was significantly more precautionary, this has been reduced to the current fish and shellfish study area following MD-LOT (2023) advice. Therefore, the revised fish and shellfish ecology study area presented in this chapter ( Figure 9.1 Open ▸ ) extends over both Scottish and English waters and is based on a precautionary Zone of Influence (ZoI) of underwater noise (100 km), including the Firth of Forth.
10. This has taken account of potential direct and indirect impacts on fish species, including disturbance or injury resulting from underwater noise from piling, temporary habitat loss and increased SSC and associated deposition. The use of 100 km as a precautionary ZoI for underwater noise aligns with both the noise modelling conducted for the Array (volume 2, chapter 10), and that of other offshore wind projects (such as Berwick Bank Offshore Wind Farm (SSER, 2022a) which found highly localised injurious effects for fish, but behavioural impacts out to the range of the low tens of kilometres. Furthermore, this ZoI accounts for fish mobility and their spawning/nursery grounds, along with capturing coastal waters to accommodate diadromous fish and their movements.
11. The fish and shellfish ecology study area provides a wide context for the spatially and temporally variable species and populations, including diadromous fish, which are known to occur within and in the vicinity of the site boundary. This fish and shellfish ecology study area will facilitate the characterisation of all fish and shellfish ecology receptors within the area and is therefore sufficiently precautionary to consider direct (e.g. habitat loss/disturbance within the site boundary) and indirect impacts (e.g. underwater noise over a wider area) associated with the Array on identified receptors.
12. Figure 9.1 Open ▸ illustrates the fish and shellfish ecology study area for the Array, which encompasses:
- the Array (i.e. the wind turbines and associated infrastructure which will be located within the site boundary); and
- the seabed and water column that could be subject to indirect impacts from underwater noise or increased SSCs resulting from activities associated with the Array and has the potential to extend beyond the Array site boundary, based on the outputs of relevant modelling (e.g. noise and physical processes modelling) as set out above.
Figure 9.1: Fish and Shellfish Ecology Study Area