Europe’s smallest whale the harbour porpoise is THRIVING in the Thames Estuary

They are notoriously shy animals, and are often hard to spot, but a new report reveals that harbor porpoises are thriving in the Thames Estuary.

The report by Zoological Society London claims that the busy waterway is a ‘critical habitat’ for Europe’s smallest whale.

Acoustic and visual surveys have revealed that ‘significant numbers’ of the animals have been living in the outer Thames, where the river meets the sea, for several years.

Scientists say the findings highlight the need for greater protection for the marine mammals from ship traffic, fisheries and offshore windfarms.

In spring 2022 the team made 31 individual detections of porpoise groups and 16 sightings, seven of which were both seen and heard

The researchers believe the Thames Estuary gives the creatures a good source of fish and can be used as a nursery for the animals to raise their young

The researchers believe the Thames Estuary gives the creatures a good source of fish and can be used as a nursery for the animals to raise their young

Europe’s smallest whale – the harbor porpoise

At just under two meters long, the harbor porpoise is Europe’s smallest cetacean – a type of marine mammal that includes whales, dolphins and porpoises.

Their small body size and life in temperate waters means that they need to almost continuously feed their high metabolism.

Due to their hypersensitive hearing, harbor porpoises are easily disturbed by noise in the water from human activities such as boat engines or construction noise.

They can also be trapped in fishing nets used by boats trying to catch other species.

The reasons behind their presence in the Thames estuary requires further research, but the team believe that a good source of fish and use of the estuary as a nursery to raise their young could be two of them.

The small whales use very high frequency echolocation clicks to communicate with each other.

The clicks are around 120 kilohertz (kHz) – more than six times higher than human hearing.

Researchers used a specialist hydrophone array to pick up the porpoises’ sounds and provide accurate information on where they were.

Two surveys carried out over seven years showed high numbers of porpoises in the estuary.

In spring 2022 the team made 31 individual detections of porpoise groups and 16 sightings, seven of which were both seen and heard.

The team from the Zoological Society London and Marine Conservation Research International believe the Thames Estuary gives the creatures a good source of fish and can be used as a nursery for the animals to raise their young.

‘Estuaries are important for many marine species, particularly for rearing young,’ said ZSL ecosystem restoration project manager Anna Cucknell.

‘The harbor porpoise is a “sentinel species” – like the old adage “canary in the coalmine”, its presence is an indication of how healthy an ecosystem is.

‘The porpoise numbers we’ve recorded in the Thames are comparable to those recorded in European protected sites, suggesting that the Thames, and potentially other UK estuaries are vitally important habitats for harbor porpoises.’

Map shows where the acoustic surveys were carried out.  The location of the London Array offshore wind farm is shown as a pale polygon

Map shows where the acoustic surveys were carried out. The location of the London Array offshore wind farm is shown as a pale polygon

Two surveys carried out over seven years showed high numbers of porpoises in the estuary

Two surveys carried out over seven years showed high numbers of porpoises in the estuary

However, Cucknell added that rapid development in the Thames is concerning, given that the porpoise population has been found to be in decline in other regions.

‘Detecting a high number of harbor porpoises in the Thames estuary this year signifies that large numbers are spending time outside of protected, offshore zones to find food and breed,’ she said.

‘Harbor porpoise are a protected species in the UK under the Wildlife and Countryside Act, but the Thames waterway is a busy gateway – with regular ship traffic, important fisheries and offshore windfarms.

‘Our intention is that our report will inform future conservation actions for this elusive marine mammal and provide evidence for wider coastal and estuary protection zones in the UK.’

Due to their hypersensitive hearing, harbor porpoises are easily disturbed by noise in the water from human activities such as boat engines or construction noise.

Due to their hypersensitive hearing, harbor porpoises are easily disturbed by noise in the water from human activities such as boat engines or construction noise.

At just under two meters long, the harbor porpoise is Europe’s smallest cetacean – a type of marine mammal that includes whales, dolphins and porpoises.

Their small body size and life in temperate waters means that they need to almost continuously feed their high metabolism.

Due to their hypersensitive hearing, harbor porpoises are easily disturbed by noise in the water from human activities such as boat engines or construction noise.

They can also be trapped in fishing nets used by boats trying to catch other species.

In 2019, five Special Areas of Conservation were designated as areas of importance for the species in the UK, including England’s southern North Sea coast at the mouth of the Thames.

MCRI scientist Dr Oliver Boisseau added: ‘We are delighted to discover that porpoises are still undertaking utilizing the Thames estuary in significant numbers, highlighting the importance of estuaries for this charismatic British marine mammals, and emphasizing the need to baseline research on protected species in other little studied UK coastal waters’.

Sharks, seahorses, oysters and seals are all living in the Thames

Scientists have performed the first full ‘health check’ of the River Thames since it was declared ‘biologically dead’ more than 60 years ago.

Results of the assessment, led by the Zoological Society of London (ZSL), reveal some surprising species living in the river including seahorses, eels and seals.

The River Thames is also home to various species of shark, such as tope, starry smooth hound and spurdog.

Despite the abundance of wildlife, the new results also revealed climate change has caused a 0.34°F (0.19°C) summer temperature rise in the Thames since 2007, as well as a water level increase.

Plastic waste is also littered throughout the world-renowned river, in the form of bottles and containers, as well as ‘mounds’ of discarded wet wipes.

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