Why are Scotland’s seals dying in their THOUSANDS? Tracking technology may have finally solved the mystery

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On the rocky islands off the northern coast of Scotland, a population of harbour seals has been struck by a strange malady.

In some areas, numbers of the doe-eyed marine mammals have plummeted by as much as 90 per cent since 2000, with scores of bodies washing ashore.

But the initial results from an ambitious study to track the animals using smartphone technology is pointing to a toxin produced by algae as the potential culprit.

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Harbour seal populations in Scotland have been in decline with the animals struck by a strange malady. Researchers have used smartphone technology to track the animals in an effort to find out what might be killing them 

The findings come from the first stage of a long-term project focused in the waters of Northern Scotland, which used GPS technology to track the seals at sea.

By tagging the animals with the same technology used in smartphones, researchers have been able to plot their movements and narrow down their feeding grounds in the hunt to find out what might be happening to them.

The harbour seal population in north Scotland and Orkney has dropped by almost 7,000 in the last 10 years alone. 

Carcasses which have turned up on the wild Scottish coast are often too decomposed to provide many clues. 

But using the GPS data to take water samples at known feeding sites has revealed traces of domoic acid, a powerful neurotoxin produced by red algae.

During blooms, these algae can spread rapidly, covering the water’s surface in 'red tides' and being eaten by fish and shellfish.

Carcasses which turn up on the wild Scottish coast are too decomposed to provide many clues. But using the GPS data to take water samples at known feeding sites has revealed traces of a powerful neurotoxin produced by red algae, may be poisoning the seals (pictured)

Seal populations in Orkney have fallen by as much as 76 per cent since 2000, and up to 90 per cent in other areas of northern and eastern Scotland in the River Tay / St Andrews Bay area

At high concentrations, the compound acts like a neurotoxin, poisoning the animal’s brain and flowing right through the food chain.

It is thought that this toxin could be behind the demise of the harbour seals.

Domoic acid poisoning is believed to be behind memory problems seen in Californian sea lions, with the toxin accumulating in sardines, anchovies and shellfish which the mammals feed on.

As part of the project, the Sea Mammal Research Unit (SMRU) partnered with mobile carrier Vodafone.

Telemetry tags developed at St Andrew's, were attached to 10 animals, glued to their fur and dropping off as they moulted.

But while the tags were attached, they transmitted information over a dedicated Vodafone network back to SMRU, revealing the animals' behaviour and movements.

More findings are expected next year, but the results of the initial tracking study on Orkney are helping the team to find out where to sample.

The data will be used as a part of a longer-term project to follow the seals in Scotland’s northern islands over a number of years to see whether or not their pups are surviving.

Water samples at the feeding sites have revealed traces of domoic acid, a powerful neurotoxin produced by red algae. During blooms, these algae can spread rapidly, covering the water’s surface in 'red tides' and being eaten by fish and shellfish

FITTING SEALS WITH SMARTPHONES 

As part of the tracking phase of the project, the SMRU partnered with mobile carrier Vodafone.

Researchers at St Andrew's University developed telemetry tags which were attached to 10 animals - glued to their fur and dropping off as they moulted.

While the tags were attached, they transmitted information over the Vodafone network via a directly back to SMRU, revealing their behaviour and movements by collected GPS and depth information. 

The data is now being thoroughly analysed to help determine why harbour seal populations have declined in some Scottish regions. 

In some regions, such as Orkney, populations have crashed by 76 per cent since 2000, and up to 90 per cent in other areas of northern and eastern Scotland in the River Tay / St Andrews Bay area.

Telemtry tags designed by the University of St Andrew's were glued to the fur of the animals, dropping off as they moulted

Bernie McConnell, a marine biologist at the Sea Mammal Research Unit based at the University of St Andrew’s, has been leading the efforts to track the animals.

He told MailOnline: 'It is possible that the decline may be due to DA but the puzzle is that we haven’t been able to establish if these animals are eating enough contaminated fish to ingest a lethal dose of toxin. 

'The dead seals that wash ashore that are examined are often too decomposed for us to determine the cause of death. 

'However, we are working hard to see if we can accurately estimate their exposure levels by measuring the levels of toxins in the fish in the areas where they are feeding, finding out what level of toxin remains in the live seals and what the health effects are of non-lethal doses of DA.' 

The data collected from the Orkney project will be used to find out why the seals are dying and if anything can be done to stop the decline.

While the tags were attached, they transmitted information over a dedicated Vodafone network back to SMRU, revealing the animals' behaviour and movement

The initial tracking phase of the study (still pictured) has revealed where the animals are feeding and their regular patterns of behaviour

Dr McConnell added: ‘This is just the start and we will be analysing the data further before presenting the findings to Scottish Government.’

Alongside the tracking project, the team is carrying out genetic analysis of Orkney's seals to find out if they are a unique population. 

The results reveal there are some genetic differences between Scottish and English seals, and even between those on the East and West coasts of Scotland. 

'We are just working on a more detailed study which will give us more data with more genetic markers on the degree of genetic differentiation within these populations and how that relates to what we know about their movements and dispersal,' said Dr McConnell.

The findings are important as any signs of inbreeding or reduced immunity could make the animals more susceptible to disease, which could devastate their numbers even further. 

THE DECLINE OF SCOTLAND'S HARBOUR SEALS

Some harbour seal populations have declined by as much as 90 per cent, while groups of grey seals have not been affected 

Two species of seals - Phoca vitulina, known as the harbour or common seal and Halichoerus grypus, the grey seal, live off the coast of Scotland.

Adult harbour seal males weigh about 187 lbs (85kg) and measure about 57 inches (145cm) in length, whereas grey seals are around a third larger.

Harbour seals are said to resemble spaniels and have a 'dog-like' face, according to Scottish Natural Heritage.

The animals live in sheltered waters and travel around 30 miles (40 to 50 km) from their territories to forage for food.

Their strongholds are Shetland, Orkney, the east coast of the Outer Hebrides, most of the Inner Hebrides and the west coast of Scotland, from Skye and Lochcarron down to Arran in the firth of Clyde, the Moray Firth and the Firth of Tay.

Small numbers of the seals can be found along the north coast and in the Firth of Forth.

The seals face threats in the form of excessive pollution such as oil spills, toxic chemicals, fish farming and entanglement in fishing nets and marine turbines.

Populations were last affected by phocine distemper virus (PDV) in 2002, but the disease is not thought to have caused numbers to drop recently.

Some harbour seal populations have declined by as much as 90 per cent, while groups of grey seals have not been affected.

Some experts believe the decline could be due to climate change, which is thought to be affecting the availability of prey such as sandeels and increasing competition for food.

Killer whales are visiting the area more frequently too, boosting predation risks.