Seals and Humans: A match or a clash?
The real question is: "Are humans disturbing seal haul outs sites in Scotland?"
Introduction
Pinniped species such as seals, sea lion and fur seal species are impacted by humans due to their time spent out with the water after foraging being on the coast or near it, engaging in social interactions, resting, and breeding. Seals are known to be selective with their choice of haul out site due to their topographical suitability which can cause an exposure the site when the tide is high, access to water when the tide is low, and areas of shelter for pups to provide safety from predators (1).
Seals around the Scotland coastline are mostly Grey seals (Halichoerus grypus) and Harbour seals (Phoca vitulina) in which their breeding season falls around the same time as the summer holiday period for humans. This can be a big concern for seals as many human recreational activities take place in the same area as the haul out sites which can be easily accessible therefore can be directly affected by pedestrians, kayaks, and dinghies. As well as these activities seals can also be disturbed by humans photographing and watching them and other activities at sea such as water sports occurring in the inshore area near where the seals have hauled out (1).
Impacts of disturbances
The impacts of human disturbances can include behavioural and physical disturbances within both species of seals. These disturbances can cause several behavioural and physical responses in seals such as onshore and offshore activities causing resting seals to raise their heads in an altered manner which then leads to them scanning the area for predators and other dangers that could affect them (1) (2). As well as this, their physical response towards disturbance would be to flush into the sea (refer to video) in which could have adverse effects during breeding season due to pups being left behind and if the mother seal does not come back or can’t locate this pup, it could suffer (1).
Additionally, these behavioural and physical responses of seals towards disturbances can have effects on the seals such as giving a great expenditure of energy and time, increase in stress and cardiac output as well as disruption to their interaction with other seals (8). Moreover, the impact of disturbances is whether that be behaviour or physical is dependent on the type of disturbance, the distance of his disturbance as well as the time of year and whether they have pups.
Types of disturbances
These types of disturbances having an impact on these seal species can include pedestrian and vehicle disturbances, watercrafts such as paddleboats, canoes, kayaks and dinghies, wildlife watching, motorboats, cruise ships, potting boats, and jet skis. The type of disturbance and the distance as well as the approach angle are all factors causing the disturbance to the seals. Also, other human activities that can cause a disturbance to the seals at a close distance are swimmers, snorkelers, and scuba divers (1)(4).
Studies have shown that the distance of disturbance from the coast or in the sea that the closer the disturbance the likelihood that the seals will act and flush into the water is higher with the approximate distance of disturbance being <100 metres in Harbour seals but for Grey seals it is approximately <150 metres (1). Additionally, during pupping season seals tend to flush when the disturbance is further out which was seen in a study done by Henry and Hamill (2001) with Harbour seals which these species were found to flush at >200m throughout pupping season which can be detrimental to the pups as they can be trampled on (6). An example of the distances of which activities being conducted by humans should be out with are shown within the table (Table 1) (1)(4).
Table 1 – Distances that should be kept from seal haul out sites (1)(4).
Legislation
The Protection of seals in Scotland is covered under The Marine Scotland Act 2010 where it is an offence to take or kill any seal except from when it is under a specific license or to relieve suffering. This Act also classifies the harassment of seals at their designated haul out sites an offence by the order by Scottish ministers. Additionally, these seal species, harbour and grey, are listed as a protected species within the EC Habitats directive 1992 within Annex II in which means they are within a community of interest and therefore their conservation requires a designated special area of conservation (SAC)(3).
Furthermore, the objective is to look at the high disturbances of at sea and coastal human activities to determine if these will affect Grey seals (Halichoerus grypus) and Harbour seals (Phoca vitulina) within their protected sites in Scotland.
Data sources
Data for designated protected seal haul out sites in Scotland was downloaded from the Marine Scotland Information (MSI) web portal. Also downloaded from the Scotland Information (MSI) web portal website was the marine recreation and tourism data from to show the marine tourism activities within Scotland. The seal haul out sites were taken from A11GI week 9 data from the conservation hotspots file (7).
The protected seal haul out data provided by the Scotland Information (MSI) web portal was from May 2017 In which 194 protected seal haul out sites in Scotland were used to monitor where seals came ashore to breed, moult, or rest. These sites used were selected by the methodology produced by the Sea Mammal Research Unit (SMRU) which was based on the seal usage patterns recorded by aerial surveys over recent years (7).
The marine recreation and tourism data provided by the Scotland Information (MSI) web portal was from August to October 2015 in which the data came from the Scottish Marine Recreation and Tourism survey (SMRTS). This data was initially taken as a baseline for marine planning but does provide information of 23 tourism and recreation activities taken up by humans focused on the Scottish coastline which can be interpreted as tourism activities which could affect the seal haul out sites around the Scottish coastline (7).
These tourism activities included, birds/wildlife watching, canoeing/kayaking, Coastal climbing, bouldering and coasteering, Dinghy racing at sea, marine and coastal recreation, marine and coastal tourism, Land yachting, power kiting and kite bugging at the coast, Long-distance swimming in the sea, Motor cruising at sea, jet skiing, power boating, rowing/ sculling in the sea, sailing and cruising, scuba diving, sea angling at sea as well as at the shore, surfing, walking at the coast, visiting historical sites, water skiing/wake boarding, wild fowling, windsurfing/kite surfing at the coast and lastly yacht racing at sea (7).
Problems with Datasets
There was only one possible dataset that could be found for marine tourism around Scotland therefore this data and the seal data did not line up for the time of year and what year it was. This could have adversely affected the results due to data gaps. As well as this, some of the activities were not used due to not having enough information within the dataset therefore would not have reflected the results within a correct way.
Methods
Base layer
Within Arc map desktop the layers were projected into WGS 31N and the coastline of Scotland was added as a base layer for the data to be added to. The seal haul out sites data were added with Grey seals (Halichoerus grypus) and Harbour seals (Phoca vitulina) as well as both seal species data included as well as protected seal haul out site data was added. Any dataset which was added and was in the wrong coordinate system was project into the correct coordinate system of WGS_31N (arc toolbox>data management tools> projections and transformations>project). The select by attribute tool was used to select out seal species in which 2 separate layers were made for each species Grey and Harbour seals.
Tourism data
The tourism data was then added but as this was raster data it needed converted into polygons to make it workable for analysis. Firstly, 6 activities were added which included wildlife watching, walking at a 2m distance from the coast and sea angling at the shore and walking for coastal activities and scuba diving, powerboating and surfing for at sea activities (The 23 activities were not used as certain information could not be found for these in the literature for distance disturbance and some of the data was not appropriate for what was needing analysed).
To convert the raster data into polygon data the first step was to individually create a raster float for each activity (arc toolbox>conversion tools>from raster>Raster to Float) the next step was to convert each activity into an integer raster therefore creating a raster layer which will contain full values with no decimal points (arc toolbox>spatial analysis tools>math>Int). To create the polygon each activity individually was put into the convert from raster to polygon tool in which this created the new polygon layer (arc toolbox>conversion tools> from raster > Raster to Polygon). Once the polygons were created the analysis was conducted.
Tourism and seal haul out analysis
The first step was to create an attribute column in each activity which would make the activity easily identifiable once the layers were unionised, to do this within each activities attribute table a column was named as that activity and using the field calculator a 1 was added to make it identifiable. Once this was done for each activity, using the grid code within the symbology properties, and setting the natural breaks at 4 this identified which was the high intensity number and this was used to select out the areas of high activity for the coastal and at sea activities, to select out the high intensity areas of activities the select by attributes tool was used.
Additionally, once these layers were created by exporting the data to a new layer, these new high activity layers were then unionised to determine which areas of high intensity activity (costal or sea) would affect the seal haul out sites around Scotland. For the unionised layer for costal activity the activities, walking, wildlife watching and sea angling at the shore were unionised and for the sea activity, power boats, surfing and scuba diving were unionised.
Once these were unionised and new layers added, using the select by attributes tool, all high intensity activity were selected out such as for the coast, when walking = 1 and power kite = 1 and sea angling =1, gave the result of the high intensity of these actives combined in which a new layer was exported and added. Likewise, this was conducted for the at sea activities when power boat =1 and surfing = 1 and scuba =1. This gave the analysis of at coast and at sea activities conducted by humans which could disturb seals at their haul out sites in Scotland.
Once the layers were all created the files were zipped and imported to arc online to make them interactive for the story map and the measure tool was used to detect the miles from the activity to the haul out to determine whether these would be impacted by the activity being conducted.
Findings
Within this first map this shows the seal haul outs located throughout Scotland. Some sites contain both species of seal, Grey and Harbour but other sites only contain the one species of seal. This map is interactive, and you can look throughout Scotland and see the main seal haul outs (HG stands for Halichoerus grypus (Grey seals) and PV Phoca vitulina (Harbour seals)).
Main areas include (press button):
Grey seal species are in less abundance than Harbour seals in which their haul outs are located mainly within Orkney which can be seen in the map, but some species do scatter around the Scottish coastline and can also be found in areas such as the west coast of Scotland in which by using this interactive map you can see these haul out sites in the west coast of Scotland.
When looking at this map, Harbour seals are the opposite of Grey seals in which their main haul outs are around the west coast of Scotland but there are some haul outs within Orkney and Shetlands but less compared to the Grey seal.
It can be seen within this map that the combined at coast activities, walking at a 2m distance from the coast, wildlife watching and sea angling at the shore at their highest intensity do not cause direct disruption to seal haul outs but at a distance they do cause some disruption due to them being within a range that seals can be impacted.
However, when looking closely at Oban (press button), you can see that one haul out site is not far from the combined at coast activities, using the distance tool this measured to be around 8.5miles from the seal haul out therefore suggesting that these combined activities could impact the Harbour seal species within this haul out.
Likewise, the combined high intensity of at sea activities, Scuba diving, Surfing and Power boating, were located around Oban in Scotland, which suggests that these activities would also impact the harbour seal haul out like the at coastal activities as these activities would take place around 9 miles away.
Walking at a 2m distance from the coastline was found to affect a total of 29 areas of which the most affected area is the south of Arran which would impact Harbour seals (click button). It was surveyed within the Scottish marine recreation and tourism survey that around 5744 people walked a 2m distance from the seal haul out being affected within Arran.
The watching of wildlife affected many sites in Scotland but the area most affected was the Ross of Mull in which around 2110 were surveyed to have been conducting this activity which caused a disturbance to a few harbour seal haul outs around Mull. Wildlife watching can cause a major disturbance if the viewers are too close and make noise which could lead to the seals flushing into the sea which can cause more harm to them (1).
Sea angling only affected one area within Scotland known as Luce Bay which is situated in the west coast between the Mull of Galloway and Burrow head. At this area there were around 470 people surveyed taking up this activity within this area which could cause a major disturbance to the harbour seal haul out leading to stress and behavioural disturbances.
High intensity of Scuba diving was found in the South of Arran in which 65 people were surveyed here doing this activity. The seal haul out sites affected by this at sea activity contained Harbour seals and by this activity being intense this could cause a disturbance to the seals within the haul out sites in Arran.
There were 2 main areas found to have high intensity surfing activity in which these were located in the west coast of Scotland and near Orkney with the most affected site being in the west coast of Scotland (press west coast of Scotland button) where 418 people were surveyed here compared to the 8 people being found to be surfing within Orkney. Both of these sites affected mainly Harbour seas but the site near Orkney (press Orkney button) at a distance would cause a disturbance to Grey seals.
The use of Power boats as an at sea activity caused the most disturbance towards seal haul out sites where the main impact was in the Isle of Mull. It was surveyed that there were 133 sightings of power boats within this area which could cause a high impact on the seals due to them being within close proximity.
Conclusion
In conclusion, the findings suggest that combined activities of at sea and at coastal activities would impact only the one haul out within Scotland, but high intensity activities conducted alone would impact other haul outs located throughout Scotland. The main activity to heavily impact haul outs is Power boating as well as this the main area found to be mostly affected by certain activities was Oban and Arran where there was a high intensity of certain at sea and at coast activities. Moreover, following the law and legislation, the combined activities being conducted whether that be at sea or at the coast would need to be moved or stopped to cause less impact towards the harbour seals at the haul out site near Oban as it is an offence to cause disturbance towards seals at their haul out sites (3).
Furthermore, the haul out sites in Scotland could be highly disturbed by human interactions due to the findings within this report showing the affects of certain at sea and at coast activities performed by humans.
Grey seal haul out in Scotland
