Abstract
Impacts on Special Protection Areas (SPAs) for seabirds are predicted to occur from the operation of offshore wind farms. In order to gain consent to construct and operate an offshore wind farm, an appropriate assessment of the potential impacts on SPAs needs to determine if there will be no adverse effect on site integrity. Where it is not possible to conclude this, a project can only be consented where there are no alternative solutions to the proposed project and there is an imperative reason of overriding public interest. When this occurs, it is necessary for compensation to the network of SPAs for the impacted feature(s) to be provided to maintain the coherence of the network.
This study reviewed the available literature for potential compensation measures for nine qualifying features of eight SPAs in England predicted to be impacted by offshore wind farm developments. Seven of these were breeding features:
- Breeding black-legged kittiwakes (Rissa tridactyla) at Flamborough and Filey Coast SPA;
- Breeding gannet (Morus bassanus) at Flamborough and Filey Coast SPA;
- Breeding guillemot (Uria aalge) at Flamborough and Filey Coast SPA;
- Breeding razorbill (Alca torda) at Flamborough and Filey Coast SPA;
- Breeding Atlantic puffin (Fratercula arctica) at Flamborough and Filey Coast SPA;
- Breeding Sandwich tern (Thalasseus sandvicensis) at North Norfolk Coast SPA; and
- Breeding lesser black-backed gull (Larus fuscus) at Alde-Ore Estuaries SPA.
Two were non-breeding features:
- Non-breeding red-throated diver (Gavia stellata) at Outer Thames Estuary SPA; and
- Non-breeding red-throated diver at Liverpool Bay SPA.
Following the review of potential compensation measures for each SPA feature, the potential for impacts to their populations to be compensated by recommended methods was assessed at three impact scenarios (low, medium and high) for three compensation scenarios (low, medium and high). This approach allowed different combinations of the three possible scales of impact and compensation measures to be explored. Impact scenarios were largely based on existing cumulative impact levels predicted for each SPA qualifying feature (low impact scenario), a pro-rated estimate of the additional impacts that might arise from Round 4 offshore wind farms (medium impact) and a pro-rated estimate of the additional impacts from 100GW associated with net-zero electricity generation in 2050 (high impact). These impact levels were based on some realistic predictions combined with some additional larger scale predictions that were likely to be less realistic (pro-rata increases for the high impact scenario less are likely as wind farms move further offshore), but useful in understanding limits to compensation measures.
Compensation measure scenarios were based, wherever possible, on empirical evidence for population responses to these measures (high compensation). In most cases, medium compensation scenarios were based on halving the level from the empirical data source (medium compensation) and halving again (low compensation). As such high compensation scenarios were the most realistic and low compensation scenarios the most precautionary.
Confidence in the ability of compensation measures to overcome predicted impacts were based on a modified version of the Intergovernmental Panel on Climate Change (IPCC) guidance on communicating uncertainty. Confidence was assessed using various metrics on the empirical evidence of populations’ responses to either impacts or management measures combined with the applicability of this evidence to the situation being assessed. This approach was then applied to the assessment method (e.g. Population Viability Analysis) used to study the efficacy of the compensation measure to the impact and the three scales described above. Narratives on these summaries of evidence and applicability were then used to describe and either justify the value of confidence reached, or to modify that confidence value up or down. These final confidence values (low, medium or high) were used to assess whether the assessment results at the three scales of impact and compensation had low, medium or high confidence of success.
Results showed that in most cases low and medium impact scenarios could be compensated for at high, medium or low compensation levels. Where the same compensation measure was recommended for more than one species, the confidence in these varied depending on the available evidence for the compensation measures and the confidence in those, or in species specific differences in ecology.
The closure of sandeel and sprat fisheries in UK waters was a recommended method for compensation for black-legged kittiwake, guillemot, razorbill, Atlantic puffin and Sandwich tern. Fisheries bycatch mitigation was a recommended compensation measure for northern gannets. Control of fox predation was a recommended compensation method for Sandwich tern and lesser black-backed gull. The creation of strict marine reserves within existing SPAs was a recommended compensation measure for red-throated diver.
It was apparent that closure of sandeel and sprat fisheries in UK waters was the single most important compensation measure that could be applied. This was predicted to positively affect multiple SPA features across a wide range of SPA in the UK and the assessment showed that this one measure could compensate for high levels of impact. As such this has the potential to be a strategic level compensation measure for the offshore wind industry, at least in the North Sea.