Current state of knowledge of effects of offshore renewable energy generation devices on marine mammals and research requirements

The report describes the current state of knowledge of effects of offshore renewable energy devices on marine mammals and then identifies a prioritised list of research gaps.

6 Research Gaps

6.1 Marine mammal

The following tables collate the Research Gaps identified in the body of this report. We group separately those that are already on-going, planned with funding identified, and proposed.

Funded Research gaps






Determine factors affecting UK grey and harbour seal habitat preference.


Using grey and harbour seal telemetry data, habitat preference will be assessed using a case-control strategy (Aarts et al. 2008). Abiotic variables ( e.g. depth, sediment type) will be used as candidate co-variates.

Funded by MS & DECC


Map distribution and activity of UK seals.


The behaviour of historical grey and harbour seals telemetry data will be classified into three states: resting (hauled-out or at the surface), travelling and foraging. To define these states we will develop existing state-space models that are based on track speed and tortuosity (McClintock et al. 2012). The results will be used:

1. to generate usage maps distinguishing between foraging and travelling

2. to investigate changes in activity budgets resulting from at-sea developments

3. to identify core foraging areas.

Funded by MS & DECC


Haulout connectivity of grey and harbour seals.


The network of movements between haul out sites will be mapped using grey and harbour seal telemetry data. We will generate a transition matrix, illustrating the probability of an animal originating from each haul-out moving to another haul-out or remaining at the haulout of origin. We will use telemetry data to parameterise these transition matrices. Uncertainty resulting from population size and number of animals tagged will result in confidence intervals surrounding these transition probabilities.

Funded by MS & SNH


Review the utility of Joint Cetacean Protocol ( JCP)


1. Monitor and report on developments under the JCP and in particular where the tools being developed under the JCP analyses to address Favourable Conservation Status at the population level, are also developed in respect of the concerns at the smaller spatial scales of marine renewable development.

2. Monitor and report on the development of methods to combine existing acoustic and sightings data to best detect population level trends.

3. Explore ways to generate probability of encounter estimates for specific OREG sites, and thus consider ways to define the "natural range" of cetacean species based on measures used for other species groups.

4. Explore ways to define optimal temporal and spatial scales at which cetacean density should best be examined in order to detect changes in density or distribution that are both statistically and biologically significant.

5. Examine existing baseline survey data, in order to assess how useful it is for determining changes in cetacean density or distribution and thereby to help refine data collection protocols to ensure that monitoring is fit for purpose.

Funded by MS


Estimation of harbour porpoise abundance from TPOD/ CPOD click detections


Convert TPOD/ CPOD output (click-positive minutes) to an index of actual harbour porpoise density (Len Thomas, CREEM).

Funded by MS


Harbour porpoise behaviour in tidal rapids


Use towed array hydrophone systems to detect and track the behaviour of vocalising harbour porpoises in the vicinity of tidal rapids associated with future tidal- OREG.

Funded by MS


Do harbour seals exhibit auditory permanent threshold shift in the presence of piling activity?


Audiograms for all harbour seals captured as part of DECC2 will be obtained using standard auditory evoked potential measurements during capture events (Wolski et al. 2003). These will be used to:

1. Identify the hearing thresholds of individual seals to assess the sensation level at which reactions occur.

2· Assess the variability of audiograms within the sample of telemetry tagged harbour seals

3· Identify evidence of hearing damage that may be attributable to exposure to piling noise.

Funded by DECC


Harbour seals' behavioural responses to the presence of piling activity.


25 harbour seals will be fitted with GPS/ GSM tags in the vicinity of piling operations in the Wash in February 2012. These data will permit:

1. Parameterising the dose-response of piling activity (source energy, range, received and perceived energy) to changes in behaviour ( e.g. movement and dive patterns).

2. assessment of change in at-sea usage, comparing pre- and during- pilling operations

Funded by DECC


Harbour seals behavioural responses to the presence of piling activity.


New data from tagged harbour seals in the Wash (see DECC2) and Thames will be compared with historic data and periods of non-operation within the current study to assess dose-response of movement and behaviour in relation to wind farm operation.

Funded by DECC


Acoustic deterrence for mitigation of pile driving activities


1. Identify potential mitigation signals

2. Conduct behavioural response trials with telemetry tagged seals.

3. Conduct behavioural response trials with harbour porpoises using 3D passive acoustic array and visual observations.

Funded by MS


Unexplained seals deaths


1. Testing the hypothetical link between shipping and unexplained seal deaths through a series of controlled tests of candidate mechanisms using model testing and full scale carcass tests with candidate mechanisms.

2. Testing the hypothetical reasons for lethal interactions through a series of behavioural response trials using both captive and wild grey and harbour seals

3. Examining the distribution of observed carcasses to identify biological and oceanographic patterns and distribution of potential causes to assess the patterns of risk associated with these unexplained seal deaths.

4 Assessing the impact of the observed and estimated levels of mortality on seal populations at a local, national and international level.

5 Identify and evaluate practical management and mitigation measures that could be developed in the short, medium and long term.

Funded by MS


Investigation of responses of marine mammals to playback of turbine noise


1. Use high resolution telemetry and active sonar to track free ranging seals and observe responses during controlled exposure to turbine noise.

2. Monitor the behavioural responses of captive seals to controlled exposure to turbine noise

3. Use high resolution passive 3D acoustic array to track free ranging porpoises and observe responses during controlled exposure to turbine noise



Collision damage assessment


A series of collision damage assessment trials with carcasses of seals and/or other species when available using a purpose built test rig. A section of turbine blade will be dropped onto seal carcasses at a range of speeds. The seal carcasses will be positioned just below the surface of a 2.5m deep pool so that the speed of impact is known and the carcass is coupled to the water and will therefore resist the impact in the same way as a free swimming seal. Carcasses will then be examined both visually and by x-ray/ultrasound to assess damage.

Funded by SNH


Analysis of visual observation data


A detailed analysis of the long term data set from the EMEC visual observation programme should be carried out to assess the likelihood of being able to detect changes in distribution or fine scale habitat use in the vicinity of turbines

Part Funded by SNH


Effects of disturbance on hypothalamic pituitary adrenal axis.


Repeated disturbance of animals (seals from haulout sites for example) may have impacts on their ability to respond normally to novel stressors (through adrenal fatigue). Before that stage is reached it is important to understand how the HPA responds to disturbance. A PhD study just starting will investigate the energetic costs of disturbance and additional research into the effects on the HPA by monitoring hormone and protein markers in excreta could be included.

Funded by MASTS


UK Marine mammal conservation targets.


Consideration of the cumulative effects of multiple impacts on neighbouring and connected populations is complicated. The IWC has a well-developed simulation framework for examining the. Work is currently being funded by JNCC to look at how similar methods could be applied to sub-populations of seals and small cetaceans within European waters.

Funded by JNCC


Unfunded/partially funded Research gaps





Fine scale marine mammal behaviour in the vicinity of a working tidal array.


1. Building on the recommendations of the Marine Scotland project, Hastie (2009) and Hastie (2012), suggest active sonar systems that would be appropriate for trialling at the Sound of Islay.

2. Consider the capability of developing Passive Acoustic Monitoring ( PAM) systems to track vocalising cetaceans around tidal turbines. Develop and test systems for possible trials in the Sound of Islay, taking account of the use of acoustic tags for seals.

3. Evaluate the ability of the above, or other, technologies to monitor potential actual impact detection.

4. Trial the feasibility of these technologies for direct observation of marine mammal movements at the Sound of Islay.


Avoidance and evasion behaviour by marine mammals in close proximity to tidal turbines.


1. Using high resolution telemetry to observe the behaviour of seals in close proximity to marine renewable devices, concentrating on tidal turbines.

2. Using high resolution 3D hydrophone arrays to monitor porpoise behaviour in close proximity to marine renewable devices, concentrating on tidal turbines.

3. Using high resolution 3D hydrophone arrays and ultra-sonic pinger tags to monitor seal behaviour in close proximity to tidal turbines.


Fine scale habitat use by porpoises in tidal rapids


Combinations of towed arrays and static 3D arrays may be used to monitor fine scale movements of porpoises within tidal rapids to investigate their use of small scale and/or transient eddies.


Telemetry studies targeted on specific areas to improve map confidence intervals.


In light of results of current telemetry studies ( and results of MR5, targeted deployments on particular species and regions will improve confidence intervals on at sea distribution maps.


Behaviour of grey seal adults in relation to high current regimes in the Pentland Firth.


There will be significant tidal- OREG development in the Pentland Firth. There is a lack of adult grey seal movement and dive behaviour data in this region - especially in relation to areas of high current flows. GPS/ GSM tags will be deployed in this region to address this data gap.


Assessment of mechanical sensing of impact with tidal turbine blades.


In cooperation with the Operator a turbine device will be instrumentation with appropriate strain and accelerometer sensors. A series of carcasses (resembling the size and mass of a seal or porpoise) will be presented to the rotating blades to determine whether the turbine sensors provide sufficient data to enable automated strike detection.


Marine mammal responses to artificial lights


Investigate responses to different light sources to identify possible illumination for night-time video surveillance.


Electrical sensitivity of small cetaceans


A series of carefully controlled tests of sensitivity of small cetaceans (porpoises and bottlenose dolphins in the first instance) to electric fields similar to those generated by OREG devices and export cables. These will necessarily be carried out in captive animal facilities. As there are no captive cetaceans in the UK such studies will require an international collaboration.


Auditory brain stem responses in pups of females exposed to OREG construction and operation noise


There is some evidence from studies in mice, sheep and humans that foetuses exposed to noise during gestation might be at risk of some hearing loss. This effect could be investigated in seal pups (using ABR response measures) from females exposed to OREG noise.


Hormone and protein markers in marine mammals in relation to noise exposure


Establishment of hormone and protein markers and noise associated dose-response relationships for the key marine mammal species found in Scottish waters. Captive studies in harbour and grey seals could determine the variability in a range of potential markers in blood, faeces, urine and skin samples taken from animals exposed to various sound sources and levels.


Ototoxic effects of PCB exposure in seals


Previous studies have shown that harbour seals in some areas have high levels of PCBs in their blubber. PCBs have the potential to cause cochlear damage during development. Further work on hearing loss in these animals in relation to their age and PCB exposure levels would determine if they have pre-existing damage caused by these pollutants.


6.2 Co-ordination of monitoring at marine renewables sites.

To date there has been very little coordination of the pre-consenting studies made at different marine renewable sites. Each site developer has a responsibility to produce evidence to support their application for permitting and their licence conditions usually include some form of pre and post deployment monitoring. The link between the monitoring requirement and the methods employed may not always be clear and in some circumstances the likelihood of the resulting data being useful for detecting even quite major effects may be low. To some extent this restriction can be alleviated and statistical power can be increased by combining data from a number of sites, covering larger areas and longer time periods. Unfortunately the methods used even in adjacent sites can differ significantly making it difficult to combine data sets. The Centre for Environment, Fisheries and Aquaculture Science ( CEFAS) (2010) conducted a strategic review of offshore wind farm monitoring data associated with FEPA licence conditions with the aim of summarising the monitoring undertaken at each site. They compared the monitoring and licence conditions between sites to distinguish between generic and site specific issues, and assessed the comparability of datasets. The eventual goal was to determine which conditions could potentially be removed or amended and to determine whether such data could be used to forecast implications of identified effects for future offshore wind farm development.

The study reviewed all natural environmental aspects of the monitoring reports including benthos, fisheries, sediment processes, noise, birds and marine mammals. The authors identified some general recommendations across the sector for future monitoring and concluded that clearer objectives within licence conditions are essential to ensure clear and realistic links between required work programmes and specific questions. They also highlighted the importance of combining datasets to utilise all available data and identified a need to develop an appropriate analytical framework.

At present it does not appear that the available information from such monitoring programmes will allow regulators to reduce the conditions attached to licences. The CEFAS study clearly highlighted the potential advantages of increased standardisation of survey and analytical methodologies to aid in future comparison and assessment.


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