The conservation impact of joining a HWDT Research Expedition
Our expedition surveys on board our research vessel, Silurian, have been monitoring Scotland’s seas for over two decades. This long-term monitoring is critical, driving protections to restore marine biodiversity and championing healthy seas for nature and communities.
UK seas are in an unfavourable state, with the conservation status of whales, dolphins and porpoise largely unknown. For marine mammals which are highly mobile and long lived (the life span of a minke whale is 30 - 50 years), monitoring over decades is essential to understand how these animals are faring, as well as identifying areas which are important for them and understanding the threats they face.
CITIZEN SCIENCE IS KEY
Since 2002, our research vessel, Silurian, has been collecting data on marine life in the Hebrides. At its core, Silurian is a citizen science project; every single data point has been collected by a member of the public and there are over 5 million! This impressive public effort has surveyed over 120,000km of Hebridean seas, the equivalent of sailing 3 times around the world. During live-aboard expeditions, people effectively become marine mammal field biologists for the duration, gathering vital visual and acoustic data.
This pioneering citizen science programme has identified where the most important areas are for species, uncovered emerging threats in our seas, and detected trends and changes in our marine environment.
IDENTIFYING IMPORTANT AREAS
Data gathered during expeditions provides evidence to policy makers to show where the most important areas are for cetaceans and basking sharks on the west coast of Scotland. Data gathered on board Silurian has helped to identify Marine Protected Areas (MPA) for harbour porpoise (Inner Hebrides and the Minches Special Area of Conservation), minke whales and basking sharks (Sea of Hebrides MPA) and Risso’s dolphins (North East Lewis MPA).
Minke whales migrate to our seas to feed, some individual whales return year after year. The longest documented sightings history for a minke whale in Europe is a whale returning to Hebridean Seas for 27 years!
OUR CHANGING ENVIRONMENT
Data gathered during expeditions has shown sea surface temperature in the Hebrides has increased 0.5 degree per decade and there is increasing evidence that climate change is impacting the cetacean populations off the west coast of Scotland.
Over the past two decades, sightings of common dolphins have increased across our survey area. Despite their name, this species was a rare sight off Scotland’s west coast in the early years of expeditions. Since 2005, there has been a marked increase in the numbers, with a twenty-fold increase in the sightings rate of the common dolphin in just 15 years. These rapid changes in our seas are cause for concern.
The first map highlights the sightings rate per unit effort (km) for common dolphin between 2003 - 2005, while the second shows the 2015 - 2017 field seasons.
Common dolphin sightings per 100 km survey effort, showing a clear increase over time.
This species was considered a ‘summer visitor’ yet our Whale Track community sightings data shows that since 2014, common dolphins have been reported to us all year round with some groups remaining in areas like Ullapool throughout the winter in recent years.
As we continue down this path of warming seas, we may well see the distribution of warmer water species, like common dolphins, shift even further north increasing their range, while cold water species, like white-beaked dolphins, shift towards the poles and decrease their range.
If our seas continue to get warmer, will white-beaked dolphins in the Hebrides be a thing of the past?
QUIETER SEAS FOR CETACEANS
Analysis of expedition data has shown that the west coast of Scotland is home to some of the highest densities of harbour porpoises in Europe. In 2018, a Special Area for Conservation (SAC) for harbour porpoise was established off the west coast of Scotland – one of the largest of its kind in Europe – with data from HWDT Research Expeditions instrumental in setting the boundary.
Acoustic monitoring is a unique element of the data collection undertaken by citizen scientists during expeditions onboard Silurian. Our seas are becoming increasingly noisy, and acoustic monitoring is revealing invisible threats, that otherwise wouldn’t be well documented. Acoustic Deterrent Devices (ADDs) or ‘seal scarers’ are deployed by the aquaculture industry to deter predation on fish stocks by seals. These devices are placed on fish farms in an attempt to scare away seals by producing an intense and aversive noise, making it uncomfortable for the seal to approach. Unfortunately, these ADDs are not specific and the noise emitted can impact other species, such as harbour porpoises.
The acoustic data collected by volunteers on board Silurian evidenced the negative impact that ADDs have on porpoises. Using expedition data, researchers revealed that ADDs are a significant and chronic source of underwater noise, which has been steadily increasing over the past decade, and showed that this noise was disturbing and displacing porpoises from important areas of habitat. Acoustic monitoring also revealed how widespread the use of ADDs had become off Scotland's west coast – in some areas the sound had ensonified the marine environment.
Noise pollution in the Hebrides
This map illustrates the acoustic monitoring effort undertaken by citizen scientists on board Silurian between 2006 - 2022 (in blue). The orange areas donate where ADDs were detected during listening stations. The shaded area of the map shows the boundary of the Special Area of Conservation (SAC) for porpoises.
These findings were used to advocate for quieter seas for cetaceans. As a result a change in policy by the Scottish Government was implemented in 2021 and the use of ADDs at marine aquaculture sites now requires an EPS license or consents from Marine Scotland (with proof that planned ADD deployment will not disturb marine mammals). Prior to this ADD use in Scotland was unregulated and largely undocumented. Since the 2022 field season, no ADDs have been recorded during expeditions.
HOW CAN I GET INVOLVED?
HWDT’s long-term research and monitoring depends on people joining an expedition. As more people participate in expeditions, the knowledge of the cetacean species and individual animals found in Scottish seas increases, alongside the evidence needed to protect them.
Anyone can take part in our research expeditions on board Silurian. Full training and support will be provided by our passionate, knowledgeable and dedicated crew - from domestic duties to survey protocol, we have you covered.
Join an expedition, explore the Hebrides, have an unforgettable experience and have a positive impact on our blue planet.
Thank you to everyone who has participated in a research expedition, without you this vital monitoring work wouldn’t have been undertaken. Thanks also to Nature Scot for funding the programme, helping safeguard this critical monitoring work over the past two decades.