Did you know… that harbour porpoise are also known as puffing pigs and herring hogs?

Alex Scorey
Senior Environmental Manager

Marine mammals can be separated into two groups: cetaceans (such as whales, dolphins and porpoises) and pinnipeds (such as seals). Consideration needs to be given to the marine mammals either living in or migrating through the region of any proposed tidal lagoon. The EIA needs to consider how animals are currently using an area (e.g. feeding/foraging or reproducing).

Marine mammals are potentially affected by the construction, operation and decommissioning of tidal lagoons through a number of pathways including: risk of collision, increased noise, barrier to movement, changes in water quality and changes to foraging habitat or food resource as an indirect impact from alterations in coastal processes.

In order to gain an understanding of the existing environment, prior to any project’s development, surveys can be undertaken to inform the EIA. There are a number of options for surveying marine mammals, the most common of which include: boat-based transect surveys, aerial surveys and acoustic surveys. It is important that the survey programme is tailored to the mammals most likely to be encountered in the area to be surveyed. These surveys, coupled with existing reports and studies, help Tidal Lagoon Power understand the current situation, and therefore better predict the likely impacts arising from the construction, operation and decommissioning of the proposed Project.


Tidal Lagoon Swansea Bay

A comprehensive desk study was completed covering records of marine mammals in the Severn Estuary and Bristol Channel, to inform the characterisation of the project area and establishment of the baseline environment. Numerous sources of information were reviewed including a number of national and regional studies to provide information on marine mammal distribution and ecology. This revealed that harbour porpoise and grey seal were the most commonly observed marine mammal species in the Severn Estuary. Ongoing monitoring includes the deployment of CPODs (which record underwater noise) in a gradient system to allow detection of any changes in behaviour before and after construction. The CPODs were installed in 2014 and will remain in place for the duration of construction and into operation. These will further inform understanding of marine mammal behaviour.

Case Study

Tidal Lagoon Plc

E: Info@tidallagoonpower.com

T: +44 (0)1452 303892

A: Pillar & Lucy House
Merchants Road
The Docks

Tidal Lagoon (Swansea Bay) Plc

E: Swansea@tidallagoonpower.com

T: +44 (0)1792 274006

A: 8th Floor
One Central Square
CF10 1FS

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