Harbour porpoise population response to windfarm construction, service traffic, and changes in prey availability

Weller, F.; Cordier, A.; Frankish, C.; Gallagher, C.; Benhemma-Le Gall, A. (2026). Harbour porpoise population response to windfarm construction, service traffic, and changes in prey availability (Report No. PrePARED Resport No. 010). Report by Aarhus University. Report for The Crown Estate.

@techreport{Weller-2026-2131194,
author = {Weller, F and Cordier, A and Frankish, C and Gallagher, C and Benhemma-Le Gall, A},
title = {Harbour porpoise population response to windfarm construction, service traffic, and changes in prey availability},
institution = {Aarhus University},
year = {2026},
month = {feb},
number = {PrePARED Resport No. 010},
url = {https://owecprepared.org/outputs/},
keywords = {Wind Energy, Fixed Offshore Wind, Noise, Marine Mammals, Cetaceans},
}

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TY - RPRT
TI - Harbour porpoise population response to windfarm construction, service traffic, and changes in prey availability
AU - Weller, F
AU - Cordier, A
AU - Frankish, C
AU - Gallagher, C
AU - Benhemma-Le Gall, A
AB - The harbour porpoise (Phocoena phocoena) is known to be affected by noise generated during the construction of offshore windfarms, and estimates of the effects of such disturbances on populations on the scale of years or decades are crucial for the establishment of suitable mitigation and protection measures. We used the DEPONS agent-based model to simulate the response of harbour porpoise populations at different spatial scales to the noise from piling operations and service ship traffic at the Moray Firth offshore windfarm. DEPONS simulates the individual movements and survival of thousands of virtual porpoises in a dynamic landscape and implements the responses of porpoises to noise from piling and ship sources. We hypothesised that at the decadal scale, the North Sea population would not be affected by the wind farm-related noise disturbance, but that impacts on the regional population in the Moray Firth might be observed.We investigated three scenarios: a control scenario with no added disturbance; a construction scenario featuring the piling schedules and ship traffic recorded during the construction period, as well as ongoing service traffic created for the forecast period; and an increased food scenario that added the effects of enhanced food availability from fish around turbine foundations to the piling scenario, at a decreasing percentage out to a radius of 500 m (based on fish surveys at the windfarm). Simulations were run for a duration of 60 years and with 100 replicates for each scenario.The simulation results suggest that, as hypothesised, noise disturbance from piling and ship traffic had minimal impact on the dynamics of the wider North Sea harbour porpoise population. Contrary to expectations, localized analyses for the windfarm area similarly show no population decreases in response to windfarm-related noise disturbance, and differences among scenarios were small in comparison to variability among replicate simulations. Further, population responses in the disturbance scenario featuring increased food biomass did not indicate any definite positive impact of the implemented enhanced food availability.
DA - 2026/02//
PY - 2026
SP - 39
PB - Aarhus University
SN - PrePARED Resport No. 010
UR - https://owecprepared.org/outputs/
LA - English
KW - Wind Energy
KW - Fixed Offshore Wind
KW - Noise
KW - Marine Mammals
KW - Cetaceans
ER -

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Abstract

The harbour porpoise (Phocoena phocoena) is known to be affected by noise generated during the construction of offshore windfarms, and estimates of the effects of such disturbances on populations on the scale of years or decades are crucial for the establishment of suitable mitigation and protection measures. We used the DEPONS agent-based model to simulate the response of harbour porpoise populations at different spatial scales to the noise from piling operations and service ship traffic at the Moray Firth offshore windfarm. DEPONS simulates the individual movements and survival of thousands of virtual porpoises in a dynamic landscape and implements the responses of porpoises to noise from piling and ship sources. We hypothesised that at the decadal scale, the North Sea population would not be affected by the wind farm-related noise disturbance, but that impacts on the regional population in the Moray Firth might be observed.

We investigated three scenarios: a control scenario with no added disturbance; a construction scenario featuring the piling schedules and ship traffic recorded during the construction period, as well as ongoing service traffic created for the forecast period; and an increased food scenario that added the effects of enhanced food availability from fish around turbine foundations to the piling scenario, at a decreasing percentage out to a radius of 500 m (based on fish surveys at the windfarm). Simulations were run for a duration of 60 years and with 100 replicates for each scenario.

The simulation results suggest that, as hypothesised, noise disturbance from piling and ship traffic had minimal impact on the dynamics of the wider North Sea harbour porpoise population. Contrary to expectations, localized analyses for the windfarm area similarly show no population decreases in response to windfarm-related noise disturbance, and differences among scenarios were small in comparison to variability among replicate simulations. Further, population responses in the disturbance scenario featuring increased food biomass did not indicate any definite positive impact of the implemented enhanced food availability.