Abstract
This report seeks to address the issues around marine mammal environmental compliance and provide options for the development of a consistent UK-wide strategic approach to marine mammal monitoring. The focus of this study is on assisting developers to meet their consenting requirements. The report assessed (1) the data required in order to assess the risks to sensitive and legally-protected species from construction, (2) the relative costs of different technical solutions, and (3) examples of how approaches might be applied based upon a number of scenarios.
The report distinguishes between two different groups of measurements that may be required. One of these, called characterisation, provides basic information about the ecological features within a region, especially those that might have specific protection under current legislation. The other, known as impact monitoring, involves measuring the effects that the disturbance due to the development is having and takes place coincident with different phases of the development. Both are essential components because the first defines the ecological value whereas the second provides information about how this is being changed as a result of the development. Nevertheless, there are difficulties defining to what extent disturbance should be allowed; clearly no disturbance is impractical but the main issue is what methods can be used to define damaging (or significant) levels of disturbance. The report raises the issue of Potential Biological Removal (PBR) as a possible mechanism. While this remains an issue for fundamental research there is a very real practical need to build a mechanism for providing clear, concise and biologically-defensible advice to Regulators about the levels of disturbance that are likely to be sustainable. The onus is upon the Scientific Advisers to provide this advice.
In general, data that characterise the likely regions for offshore energy development are available from recent and ongoing research. However, these are generally collected at spatial and temporal scales that are much greater than are likely to be needed. It is almost certain that some form of measurement of population trends of the more abundant and sensitive species (it would be impossible with the rarer species) will be required if there is to be effective measurement of impacts.
Detailed methods have been developed to characterise marine mammal populations and these could be adapted to allow measurements at the spatial and temporal scales required for impact monitoring. However, the power to detect changes in population trends that could be significant is usually very low. There tends to be a direct relationship between statistical power and the amount of data collected. Even very significant changes in abundance are difficult to detect reliably without considerable effort and cost. Emerging technologies may provide partial solutions to this but these are mostly still at the early stages of being tested and many, such as HD photography, have significant potential difficulties attached to them and need rigorous testing.
Overall, aerial surveys are more cost-effective than ship-based surveys but aerial surveys may not be appropriate in all situations. It appears to be wise to design surveys for particular regions specifically to suit the problems associated with each region. This could include the expected type of sensitive species to be detected, exposure, distance from land, and whether it is necessary to measure relative versus absolute abundance to detect trends. Because of the many different variables that have to be taken in to consideration, it was difficult within this report to provide a template for survey design. We recommend that the design of monitoring procedures should be bespoke for each situation but that there should be open consultation on these designs before they are implemented.
Given the general difficulties there are with providing the kind of information needed by Regulators to ensure that developments in marine renewable energy are legally compliant, we recommend a licensing procedure that initially includes precautionary assumptions within the licensing conditions. These conditions may then be relaxed if and when evidence is provided that disproves the precautionary assumptions.
Given the scales of offshore renewable energy development envisaged together with the predicted spatial extent of some impacts, there is the potential for a strong interaction between adjacent developments. This means that the activities of individual developers cannot be seen in isolation and some level of co-design of marine mammal monitoring, including implementation, needs to be considered. Such co-design has further advantages in that this could occur at scales that have better congruence with the natural spatial distribution of marine mammal populations and also with current data resources, as well as the current methods that are available for determining distribution and abundance. If this is to be implemented most effectively it will require a radical change in the current vision, on the part of both Regulators and Developers, for compliance monitoring of marine mammals around renewable energy developments with a move towards an increase in the spatial scales for monitoring to cover large sections of the UK regional seas.