Mapping the exposure of dolphins and porpoises to ship noise in the English Channel

Using at-sea data to map the exposure of common dolphins and harbour porpoises to ship noise in the Western English Channel
Leaping dolphins in the English Channel

Mapping the exposure of dolphins and porpoises to ship noise in the English Channel

Using at-sea data to map the exposure of common dolphins and harbour porpoises to ship noise in the Western English Channel
Title: Mapping the exposure of dolphins and porpoises to ship noise in the English Channel: Using at-sea data to map the exposure of common dolphins and harbour porpoises to ship noise in the Western English Channel
Funded by: Natural England
Funding amount: £256,323.12
Location: UK
Dates: 1 July 2026 – 31 March 2029
University of Plymouth PI/Co-I: Dr Simon Ingram (PI), Professor Clare Embling (Co-I)
University of Plymouth staff: Beth Harvey
 

Overview

Noise pollution in coastal waters must be monitored and managed in accordance with UK Marine Strategy Regulations, but we only have a limited understanding of how severely this noise impacts cetaceans (such as porpoises and dolphins). 
The English Channel is one of the busiest shipping routes globally, meaning species who live there are exposed to high levels of ship noise. Our research has been instrumental in identifying the Western Channel Important Marine Mammal Area (IMMA) within a global International Union for Conservation of Nature (IUCN) initiative.
By collecting large-scale data on seasonal distributions of cetaceans throughout the IMMA, this project will assess exposure levels of noise pollution experienced by harbour porpoises and common dolphins in UK coastal waters.

This project is a fantastic opportunity for us to build on previously unfunded survey work we have been conducting in the English Channel to map the distribution of marine mammals and for us to make a vital contribution to our understanding of the impacts of noise pollution on vulnerable species of dolphin and porpoise living in our coastal waters.

Simon IngramDr Simon Ingram
Associate Professor of Marine Conservation

 
 
 
Harbour porpoise
Propeller of ship from underwater

Objectives

  • Collect survey data. Conduct a total of 20 year-round at-sea surveys (five days at sea in each survey) between July 2026 and September 2028 throughout the Western Channel IMMA using visual and acoustic line transect surveys. These surveys will consist of up to five days (depending on weather) of visual observer and hydrophone passive acoustic surveys in zigzags from the shore (10m depth contour) out to six nautical miles from the shore. This design will give the most efficient coverage of the coastal waters in the Western Channel IMMA. Survey coverage will include all waters out to 6nm from the Isles of Scilly to Eastbourne in West Sussex.
  • Model the habitat by compiling seasonal spatially predictive species distribution models and to estimate relative abundance of cetaceans throughout the Western Channel IMMA. This analysis will use boat survey track data to provide effort corrected sightings rates throughout the surveyed waters.
  • Model the noise exposure by overlaying CEFAS noise propagation spatial models on our animal distribution models and using published, species-specific audiograms to estimate exposure levels experienced throughout the IMMA for common dolphins and porpoises.
Common dolphin
Dolphins racing a ship

Context of the issue

There are several knowledge gaps regarding the conservation of small cetaceans in the English Channel. For example, we know that common dolphin abundance has increased in the past decade in this area but we do not know how these numbers change seasonally or the relative changes in abundance over time. We also know that harbour porpoise numbers have declined in recent years. Cetaceans in the Channel experience a burden of multiple human stressors, of which noise exposure is, as yet, unquantified.
There is currently limited understanding of the seasonal distribution of cetaceans in the waters of the English Channel, no understanding of the level of exposure of cetaceans to ship noise in the English Channel, and no known thresholds established for limits of acceptable noise exposure to cetaceans in line with UK Marine Strategy Regulations and the maintenance of Good Environmental Status. Understanding these factors is key to conserving the cetaceans in the Channel.

How the project addresses the issue

This project will estimate noise levels in concentrated areas of habitat use by common dolphins and porpoises throughout the year. It will then provide the first assessment of exposure to shipping noise in the most critical coastal region of the UK in terms of overlap between cetaceans and shipping. 
The outputs from this project will make a significant contribution to setting thresholds to noise exposure experienced by cetaceans in UK waters.
The surveys and analytical approach it adopts will serve as a benchmark for future research in this geographical area or applied in other coastal regions of the UK. The standard survey design can be applied to future monitoring and survey efforts to measure animal distributions and noise exposure in future decades.
 
 
 

Funded by

Centre for Marine Biology and Conservation Science (CMACS)

CMACS unites the University of Plymouth's long-standing and internationally recognised research in marine biology and marine conservation science. 
By providing an inclusive and supportive atmosphere for knowledge exchange and relationship development, CMACS drives ambitious, innovative, interdisciplinary, world-class marine research.
Man fishing in small boat above coral reef, CMACS