Thames porpoise survey – SOTW returns to port

The first ever dedicated survey for harbour porpoises (Phocoena phocoena) in the River Thames was completed on Saturday 14th March, with R/V Song of the Whale returning to her home port of Ipswich. During the week long survey of the Thames Estuary, groups of harbour porpoises were encountered on 17 separate occasions. Passive acoustic detection systems assisted in the search for these iconic and elusive marine mammals, as listening for the characteristic sonar clicks of this species is often a more effective way of determining the presence of harbour porpoises; indeed, a preliminary investigation of these acoustic recordings suggests more than 100 separate detections were made of porpoises as they foraged for food beneath the surface waters of the estuary. The team held a public open day at the Hermitage Community Mooring in Wapping, on Sunday 8th March, which was well attended by over 100 people, including lots of children, who were very excited to discover that porpoises live in the estuary and to have an opportunity to explore the boat.

MCR, along with project partners IFAW and ZSL, will conduct an additional survey in six months’ time to establish if these encounters represent a year-round return to the Thames or are part of a seasonal peak in the spring. Anyone seeing a harbour porpoise or any other marine mammal in the Thames Estuary are encouraged to submit the information to ZSL’s Thames Marine Mammal Survey .  Please support MCR’s ongoing efforts to make this survey and others possible.

The map shows the track of R/V Song of the Whale during the recent survey (6-13 March). Porpoise sightings are shown as blue triangles and acoustic detections are shown in red and orange. These findings are preliminary and a more detailed analysis is underway to derive density estimates of porpoises in the Thames; this will allow a comparison of the numbers in the tidal Thames with other parts of the UK.