Marine Mammals of our Biosphere
The Sussex coast may not be the first place that comes to mind for spotting sea mammals, but you might be surprised to know that dolphins, seals and occasionally even whales are spotted in and around the sea of our Biosphere each year!
The species of dolphin most commonly seen is the
bottlenose dolphin a large coastal species that can reach 4m in length. These are transient animals, passing through but occasionally, when food is abundant, a group of dolphins may remain in the area for a week or more.
When I first started to monitor Sussex Sea mammals in 1991, bottlenose dolphins were regularly seen 100 to 200m from the shore every year at Brighton, usually swimming west to east. Sadly an increase in water sports and other human activities has meant that inshore sightings have declined.
However, we do receive some very interesting offshore sightings of bottlenose dolphins, usually bow-riding and playing around vessels. For example in 2015 we had a number of sightings of a large group of bottlenose dolphins, including several juveniles, throughout July and August. These dolphins also came close enough to be seen from the shore – including at Brighton, so its worth keeping your eyes pealed!
Bottlenose dolphin group © Luke Biddlecombe 2015
Part of a group of 30+ bottlenosed dolphins August 2015
Two other species are seen from time to time:
- the common dolphin, a deep water species, identified by its characteristic long beak
- the shy harbour porpoise (the only porpoise species in the UK), that can be identified by its triangular dorsal fin and its lack of a beak.
Sea Watch Foundation produces some very useful species guides which you can
download.
However, when we receive a report from the public we can never take it for granted that the sighting is a bottlenose or common dolphin or harbour porpoise. Very rarely
other species can be seen such as the pilot whale, bottlenose whale Atlantic white-sided dolphin and even larger species such as minke whale, fin whale and humpback whale. There is always the chance that one of the less common species may pass the coast: 28 species have been recorded around the UK, 14 of which are recorded regularly. Before commercial whaling however, many of these species would have been common visitors to the English Channel!
Sussex sightings are part of a national picture, forming one of 35 regional groups of the Sea Watch Foundation. Each year SWF runs ‘National Whale and Dolphin Watch (which is in its 15
th year), which this year will be 23
rd to 31
st July - details of how to take part are
here.
Seal sightings have been on the increase, partly due to better reporting by the general public.
Common seals are seen more frequently in the Biosphere than the larger
grey seal. Not restricted to the coast, seals frequently travel up river and can be seen on both the river Ouse and the river Adur, both of which are very tidal in nature. Sightings are more frequent in the winter months when stormy seas make the coast more inhospitable and rivers provide a welcome source of food.
Grey and Common Seal Comparison © Steve Savage 2013
The difference in head shape/silhouette is the best way to identify the grey seal (left) and common seal (right)
Seals are largely solitary and usually seen on their own, and people who report a sighting often assume that they are lost or in trouble. Unlike dolphins and whales, seals are far better adapted to estuary and river life and seem quite at home when we see them. In fact we have already had a few sightings so far in 2016.
Seals are amphibious so they can haul out and bask on a river bank. Seals also seem to ‘understand’ tides and will haul out at low tide and hunt at high tide. They also use the outgoing tide to take them back down to the sea. Dolphins and whales in contrast can often get disorientated in a river because they rely very much on their echo-location to navigate. A seal may hang around in the same river for several weeks, traveling up and down with the tide and hauling out in different locations.
Common Seal River Adur 2016 © Paul Loader 2016
Common seal hauled out on the estuary mud at low tide, River Adur January 2016
Most of the seals we see in and around the Biosphere are juveniles. Older seals tend to travel less and stay nearer to their breeding beaches. But juvenile seals may travel far and wide before becoming more settled. In 2009 I took part in an electronic seal-tagging project run by the Wildlife Trusts’ South East Marine Programme and Chichester Harbour Conservancy. The project tagged 5 seals in the Chichester Harbour area, one of which swam as far east as Shoreham. In 2007 a tagged common seal even visited Sussex from across the Channel. I also provided an
education programme for the project which schools can book on to.
Occasionally seal pups or sick or injured adult seals are found on the beach and we work very closely with
British Divers Marine Life Rescue to monitor these seals. I also occasionally go out to dead sea mammal strandings, in coordination with the London Natural History Museum
stranding network to ensure important data is recorded. One of the most common dead stranded sea mammals in Sussex is the harbour porpoise.
Dolphin Rescue Activity © Steve Savage
School children learn about threats to sea mammals and discover how to rescue a stranded dolphin
Sea Watch Foundation is a scientific charity with which I have been involved over the last 22 years on a voluntary basis. Part of this work involves raising awareness of UK and Sussex sea mammals. Bottlenose dolphins, harbour porpoise and common seal are all national UK Biodiversity Action Plan (BAP) species. In fact Common seal populations in the UK have declined by over 50% in the last 15 years. So we regularly take part in local events to raise awareness of UK sea mammals and threats such as plastic pollution and climate change.
Shoreham Beach Local Nature Reserve as a central location on the Sussex Coast has become the ideal site to coordinate sea mammal monitoring, and dolphins and seals also feature in the
nature reserve marine education programme.
The public have been a great help in reporting dolphin and seal sightings, especially as these animals’ movements are erratic and less predictable than other mammals. However even a simple photo can reveal if it’s a common or a grey seal, a bottlenose or a harbour porpoise, which is an essential piece of information for it to be added to our database. I have also been able to track the movements of a few common seals by unique spot patterns and again the public have been a great help by forwarding their pictures – almost every mobile device has a camera nowadays so there’s no excuse not to send through an image if you are lucky enough to spot a marine mammal!
The
public really can play an important part through ‘citizen science’!
Sightings can be reported at
seawatch17@yahoo.co.uk .
Sussex sightings are also posted on the
Sussex Marine Jottings weblog.
So when you are next down on the beach or strolling along the river bank, keep an eye out for one of the Biosphere’s more unusual mammals. Dolphins and seals can be seen from the beach, but raised areas such as cliff tops, piers and Brighton marina are good locations for spotting dolphins and porpoise. If you see a seal hauled out, do enjoy them from a distance and if you are walking your dog, please keep them on a lead when passing a basking seal.
Good luck and happy ‘hunting’ of sea mammals!
Steve Savage - Biologist, Environmental Educator, Wildlife Author
Sussex Regional Coordinator, Sea Watch Foundation, & Sussex County Recorder for Sea Mammals