WDCS Fieldwork Blog

As WDCS fieldwork in Gairloch, in the North-west of Scotland comes to an end, we hear from Ian French, owner-operator of Gairloch Marine Wildlife Centre & Cruises (formed in 1989 as Sail Gairloch), where marine survey data has been collected over the last two decades. A marine biologist (specialising in sublittoral biology particularly spirobis tubeworms), since taking over the business, Ian has expanded the data collection to include noise pollution and disturbance. Harbour porpoises are a focal species for Ian. 

Loch Gairloch has proved to be a small but perfect study area for cetaceans with many species being recorded over the last twenty-one years. Being the smallest of the UK cetaceans, harbour porpoise are fairly hard to study, spending fractions of a second at the surface. Due to the poor mass / surface area ratio and possessing only a thin 12mm layer of blubber they have to continuously swim to maintain the core body temperature. They will eat any kind of fish and crustacean but have a tendency for bottom dwelling fish. Ian has helped in several necropsy's on harbour porpoise and gathered a considerable amount of important data on stomach contents, age and bio accumulated chemicals within the blood and tissues.

Porpoise tend to be seasonally migrational with the onset of winter the porpoise tend to leave the Loch and head out into the deeper water where they have been recorded feeding down to depths of 300 metres. With the return of spring, coinciding with plankton blooms and sand eels returning from semi hibernation the porpoise return to the coastal feeding grounds, with the pod numbers steadily increasing through the year. As marine surveys begin in the spring the porpoise have little interest in any interaction, primarly feeding and foraging. By mid summer calves are born and interaction with the survey boat increases. The behaviour exhibited is almost as if the mothers are 'showing' the newborns a boat.

A slow quiet approach near to where the porpoise are feeding, stopping and sometimes shutting down the engine is often rewarded with good interaction with breathing clearly heard.  Reinforcing the name 'puffing pig' or 'pig fish'. Young calves are often seen to be logging, panting at the surface as if catching thier breath. A lot of interaction at this time of the season is probably due to the ease of feeding and often play behaviour and mock fights and lunges are regularly witnessed.



Gairloch porpoises do not seem to behave as others and many dolphin researchers have spent time aboard the research vessel Starquest and dispute what they are seeing until clearly recognising the cetacean as a harbour porpoise and not a dolphin.  Approaching slowly and stopping off at distance it allows the porpoise control and confidence with the situation resulting in good interaction with the passengers and boat.

The harbour porpoise have a life span of around thirteen years, this is reinforced by tooth data collected by Ian, and as many are seen to be born in Loch Gairloch the porpoises here seem to become habitualised with the research vessel, quite simply unique behaviour. Non-invasive survey techniques are used, including digital photo survey and video and acoustic data collection via a purpose built hydrophone. 

Pollution with chemicals into the seas is a problem for everything but manifests itself in the porpoise in the form of skin legions and ulcers. Again necropsys aided by ian have shown high levels of PCBs (polycholrinated Biphenyls) acumulated in the blood and skin layer of the harbour porpoise. Possibly the biggest problem the harbour porpoise have to contend with is noise and data collected has shown noise pollution to be a major factor in the population abundance of the harbour porpoise.



Feeding by sonar, porpoises simply cannot find food if the sea is full of boat traffic, particularly speed boats with such speed and power they produce a vacuum cavitation underwater creating an enormous sound level. With sound travelling five times faster in water and many times further porpoises are moving away from busy areas and indeed have become forced out of certain areas around the UK with the  direct increase in pleasure craft taking to holiday hot-spots. Thankfully Loch Gairloch has not become too noisy although sightings data has shown a declining population which gives cause for future concern.

NATO disturbance in the area is another cause for concern, indeed Gairloch Marine Wildlife Centre was part of a pressure group that successfully persuaded NATO and the MOD to change the timing of their large scale manouvers which used to take place during June / July right in the porpoise and dolphin calving season. In the past this resulted in many dead porpoises and aborted feotusus but thankfully March and October are now when the joint operations take place although data suggests again that cetaceans leave the area during these live firing operations.

Given the weather that we've been privy to these past few days, anyone could be forgiven for thinking that we were anywhere else but the north-west coast of Scotland ... in October!! Up here, we're not that far from the Arctic Circle and at this time of year we could only dream of blue skies, a toasty sun and no wind ... but our prayers were answered and for the first time in almost a week we were able to see across to the Isle of Skye and we've been basking in the few days of "Indian Summer" that were forecast - although i have to say, I've been to India and an Indian Summer it was not ... warm yes, positively tropical, no! The only thing missing from it being classed as 'ideal sighting conditions' were a few clouds to keep the glare away but ... we weren't complaining.

Our survey area has been positively bubbling with animals and over the past few days we've been lucky enough to see an absolute plethora of marine critters passing by our doorstep. Harbour porpoises have been the most abundant, with over 60 individuals spotted in one day ... from lone animals to groups of 8, the most pleasing sight is that of mother/calf pairs gently rolling through the glassy calm waters of the Minch. A few minke whales are also still hanging around, possibly just filling up on as many sand-eels as they can before they move off to their wintering grounds, and another seasonal visitor, the basking shark have also been plentiful - although it's worth noting that the majority of them appeared not to be "basking" and instead were seen propelling themselves at great speeds through the water.





Although not venturing close enough to identify to a species-level, two separate pods of dolphins (at two separate times) were spotted in the north of the survey area. They were incredibly boisterous and demonstrative and were spotted breaching repeatedly and making a lot of splashes for an extended period of time! At one point however we were holding our breaths as we spotted a German Frigate (the German equivalent for HMS .. "Bremen"), heading straight for one of the pods. They were getting closer and closer and we were almost considering calling them up on the radio to warn them about what was ahead (and to ask them to identify the species for us!!) when at what seemed was almost the last minute (although admittedly distances can be deceptive at sea) they changed course and veered off to starboard and thankfully avoided what could have been a rather messy situation!



Our sightings wouldn't be complete without mentioning the other members of the animals kingdom that we encountered; both grey and harbour seals, eider ducks, noisy geese flying overhead and the avian equivalent of a killer whale (as in being a relatively infrequent visitor, and inducing jumping up and down behaviour by the spotter) ... a pomeranian skua!

The beauty of the north however hasn't only been confined to the daylight hours and we were treated to possibly one of the most magnificent natural wonders of the world ... the Aurora Borealis! Lighting up an otherwise star-studded sky (the milky way is like a white streak across the centre of the black sky - no light pollution up here!) the green and blue oil-slick'esque marvel that is the Northern Lights flickered across the northern extreme of our survey area and made us feel even ore humble than we had been before.

As the title suggests, we now hear from WDCS's Sarah Dolman on what's being done around the UK to protect harbour porpoises. Sarah also wants to thank Jo Clark for text taken from the WDCS UK MPA report. Over to you Sarah (and Jo) ...!

Harbour porpoises are the most commonly sighted and stranded cetacean in UK waters. The smallest and most numerous and widely distributed of UK cetaceans, they can live for up to 20 years. Calves are seen between February and September in UK waters, with a peak in June. In the UK you can find the highest densities of porpoises in the Hebrides, north-east Scotland and coastal Wales.

There has been considerable concern for the porpoise status in some regions in recent decades due to apparent declines in numbers of sightings and strandings, and impacts which include ongoing high levels of incidental catches in fishing nets. Pile driving is likely to be a conservation issue for porpoises in the future as this intense and impulsive sound will dominate in coastal waters in coming decades as we erect wind farms around the coastline.

In many areas porpoises are present throughout the year but there do seem to be seasonal changes in distribution and sightings rates, most likely linked to prey availability and the location of suitable breeding and calving habitat. For example, a pattern of peak harbour porpoise numbers off the shelf in May and June, followed by a peak in numbers on the shelf two months later, is thought to relate to calving. These aggregations, occurring in August-September, have been noted for several coastal locations around the UK and coincide with the peak final months of the mating season for harbour porpoises, with social and sexual behaviour frequently observed.

Due to their small size and the lack of markings on their fins that could otherwise allow recognition of individual animals, understanding site fidelity and whether porpoises show regular movement patterns between areas is challenging. However, resightings of highly marked individuals do occur and this indicates a degree of site fidelity. Female porpoises disperse less than males and this may indicate that females stay in the places that they calve and nurse their young.



Important foraging habitat for harbour porpoises includes areas of strong tidal currents, usually near islands or headlands, where the currents combine with the seafloor topography and seem to create conditions where prey become aggregated. For this reason, development of a wide-scale tidal industry, likely to be utilizing these same tidal currents, could have a negative impact on porpoises but no research has unvestigated this yet.

Although there is some variation in prey depending on area, season and age of the porpoise, dietary studies have found that sandeels are the most important prey species for north east Atlantic harbour porpoises during the spring and summer, and whiting in the autumn and winter months. These will be supplemented with other fish such as herring, mackerel and gobies throughout the year.

Anatomical and genetic studies on harbour porpoises to understand population structure have indicated that several populations and subpopulations exist in the North Atlantic. In UK waters, genetically differentiated subpopulations exist in the Irish Sea/Wales and the North Sea, with some possible further divisions of the North Sea population.



Understanding population structure is important for conservation efforts. It is likely that the effects of regional threats such as bycatch, naval sonar or marine renewable energy will be underestimated if animals are thought to be part of a single, wider population but actually form discrete subpopulations.

The harbour porpoise is protected under UK and European law (on paper), yet no marine Special Areas of Conservation for harbour porpoise have been established in UK waters and all the threats they face, including bycatch, continue.

Volunteers Bea and Charlotte tell us about the last week...

Thursday saw the all female 'Hula Balullas' and 'Ginger Ninjas' crews commandeer Pagan, a sailboat, from Pwllheli to Bardsey Island and back.  Skipper and willing amateur conservationist, Jacki Clark, came all the way from Macclesfield to meet us in Pwllheli marina, where we discussed the day's plan and safety briefing over hot chocolates in her comfortable cabin.

The trip started well at midday, with the sun shining and good sightings of grey herons, cormorants and oystercatchers at at the mouth of the marina.

Our spirits were high, but unfortunately, so were the waves..... once out of the harbour we soon realised the extent of the swell, which make it a tricky day for spotting cetaceans.  But there was plenty of other wildlife to be seen.....

On the south end of Bardsey, in a quiet bay, almost fifty Atlantic grey seals (Halichoerus grypus) were spotted basking on the rocks.  Among them were pups, some being only a day old, still adorning their fluffy white coats.  Curious adults surrounded the boat trying to decipher the unexpected visitors.

Reaching the North end of Bardsey Island, the waters were littered with sea birds, including puffins in their winter attire, Guillemots, Razorbills and mixed sea gulls.  Northern Gannets were also seen circling above the surface, which can be used as a good indicator for fish shoal presence and feeding marine mammals.  We circled the area hoping to get a glimpse of the elusive Risso's dolphins, which had been sighted of the Island's north end days prior to our visit.  Although there were numerous birds circling and resting on the surface, no harbour porpoise , Risso's or bottlenose dolphins were sighted.  

At around 4.20pm it was time to start the return journey to Pwllheli and so we sailed with the wind behind us. It was great to be out on the water at this time, with the sun setting behind us casting a beautiful glow and we kept ourselves entertained on the three hour journey back with jovial sing alongs to the harmonica and tin whistle. Although a very enjoyable day there were no cetaceans recorded. However, later on a report came in from the Bardsey crew 'Life Aquatic', of seven Risso's dolphins, traveling past the North end of Bardsey, the exact spot we had been earlier- such a close miss! The dolphins were recorded as breaching the water, foraging and milling about half a mile of the coast.     

At the end of the week the crew changed over, with 3 new members joining us from head office. Angela, Rachel and Pete have settled in well. Pete heading over to join Rob on the island and Sam returning to join the mainland crew. The weather has been perfect for spotting over the last few days, with calm seas and glorious sunshine, sometimes we have to remind ourselves that we are in North Wales in October! We have had lots of harbour porpoise sightings from both the mainland platforms, which, along with the fine weather, have put big smiles on our faces! 

P.S. We have also had a great sightings of a sheep rock climbing at St.Mary's Well. We have named him 'Cliff- the extreme sheep'!

The extreme gale force winds that we have been experiencing in the last week seem to have finally dissipated. We’ve been thinking about our colleagues who are also working in the field in Bardsey Island in North Wales and wondering if they have been as blown around as we were up here in northwest corner of mainland Scotland.

We’ve had plenty to keep us occupied even though we haven’t been able to conduct watches! Once we had a sighting of our first warship in the northern part of our survey area they multipled in number on a daily basis, up to six at one point. From massive aircraft carriers to frigates and fighter jets, we had them all, and we had a wind-inducing close encounter with a Royal Navy helicopter, which flew right in front of us in our field study site - they filled up our ‘big eye’ binoculars!

We also observed two intense, short and distant flashes in the night sky north of Skye. Mysterious. They were over too quickly to be flares. And ‘Big ears’, our underwater acoustic listening system, also recorded three different types of active sonar filling the Minch! No wonder no animals were heard. Maybe all the marine wildlife has travelled south to avoid the noise – maybe even as far south as Bardsey…??



Sightings of the wildlife sort have been more avian than cetacean, mainly due to the extreme gale force winds, although Nicola observed a pair of porpoises on one of the short watches when the Minch calmed down enough for us to don our thermals and go on effort for the first time on Saturday. Large flocks of noisy geese have been flying in ‘V-formation’ over head all week, in groups of 30-50. We had more than 60 eider ducks rafting on the water in front of our field site and a white-tailed sea eagle (minus the white-tail!) majestically circling in a thermal current over head for several minutes.



With high pressure expected over the UK for the rest of this week, we are optimistic to be watching every day. The warships have moved away now, perhaps they have gone further north. Without sonar filling the Minch we hope to have some cetacean encounters – it was this time last year that we observed ‘John Coe’ the infamous killer whale cruise through our field site! Fingers crossed…