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Winter Dolphin Research Project
Independent Marine Consultant and photographer Marijke de Boer is carrying out winter surveys for marine mammals aboard the supply vessel the Gry Maritha.
Winter Dolphin Research Surveys started in January 2007 and species thus far recorded are harbour porpoise (Phocoena phocoena), grey seal (Halichoerus grypus), common dolphin (Delphinus delphis), minke whale (baleanoptera acutorostrata), bottlenose dolphin (Tursiops truncatus) and Risso's dolphins (Grampus griseus).
Little is known about cetaceans (whales, dolphins and porpoises) that occur in the waters off Cornwall. There is considerable concern about the scale of cetacean bycatch (incidental entanglement in fishing gear) in the fisheries to the south of the UK. Primary evidence for the scale of the problem has come from stranded cetaceans, predominantly short-beaked common dolphins and harbour porpoises, recorded in the winter months on the English and French coasts. The significance of the impact that bycatch poses to populations is unclear as little is known about the numbers of cetaceans that frequent these waters at this time of year.
Seven different species were positively identified during previous surveys carried out in the waters to the south of Cornwall since January 2004, these were bottlenose dolphin, short-beaked common dolphin, striped dolphin (Stenella coeruleoalba), harbour porpoise, Risso's dolphin, minke whale and fin whale (Balaenoptera physalus).
It is important to estimate an index of density for the inshore winter common dolphin and porpoise populations by following random and fixed survey transects. Obtained photographs will enable us to study the residency of small cetaceans. In addition, we will document the surface behaviour of small cetaceans. The passage between Penzance and the Scilly's therefore offers a unique opportunity to collect information on cetaceans in a consistent and scientific manner.
Winter Sightings Map 2008
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SEA LIFE SIGHTINGS 2008
See article published in the Western Morning News : 11 February 2008.
28th January 2008
Similar to last year, we are continuing our dolphin research this winter aboard the supply vessel the Gry Maritha in association with the Isles of Scilly Steamship Group. Our first survey took place last week taking advantage of a calm weather window!
The Gry Maritha set sail on Monday the 28th of January during light southwesterly winds. As we passed Gwennap Head a huge ‘feeding frenzy’ was taking place. Seabirds were actively diving into the small waves with auk species (guillemot and razorbill) together with harbour porpoises working underwater pursuing the fish to the surface! Quite a spectacular sight!
Risso’s dolphins were seen when we were passing the Wolfrock Lighthouse. These dolphins can become almost white with age as they become covered with white scars. The scars are a result of playing and fighting with each other! The dolphin kept their distance as they are usually rather shy and tend to avoid boats.
Nearing the Scilly’s a huge tall blow was seen! The long dark brown body with a small dorsal fin was seen and the whale was positively identified as fin whale! This is the second largest whale on the planet (only the blue whale is bigger!). Our research has found that the fin whale comes to feed in these waters during winter and it was great to see them again! Only one whale was seen, however, the crew of the Gry Maritha had seen a large whale a few days ago off Wolfrock! Let’s hope they stay around and we see them again!
13 and 14 February 2008
During the last week we went out on another productive crossing with the Gry Maritha. The easterly winds made the crossing to the Scilly’s rather smooth and with the sunshine in our faces it was like summer had arrived already! The return crossing however was a very different one as the easterly wind was fresh to strong and winter was back for sure!
A group of bottlenose dolphins were seen off Penzance harbour and were showing some impressive acrobatics! Off Gwennap Head a few porpoises were seen speeding through the water in the strong tidal currents.
Approaching the Scilly Isles a small bushy blow was seen followed by a large dark back sliding through the water. A better look of the animal confirmed it was a minke whale! These whales can grow up to 10m in length and have been seen during previous surveys. Their site-fidelity indicates that these waters are an important feeding habitat.
The storms we had to endure during the last weeks have been mixing the water masses which in turn triggered the onset of a spring algae bloom. The sea birds, in particular the guillemots and razor bills, are rather busy taking advantage of this. We also saw a rare Glaucus gull which followed the vessel for quite some time. Overall, we noticed that there were more fulmars flying by. These birds are family of the tube-nosed seabirds and are closely related to the albatross!
20 and 21 February 2008
With shifting easterly winds we took the opportunity to continue our research aboard the Gry Maritha. The sea was incredibly calm and conditions were great! To our surprise we hardly made any sightings when we passed Land’s End and we were puzzled where all the porpoises and gannets had disappeared to? With daylight starting to fade once we were over the shipping lanes we did manage to sight a slow moving basking shark but no dolphins or porpoises were seen. We could only keep our fingers crossed hoping we would see them the next day.
We were lucky! And it soon became apparent that all wildlife had been concentrating just off the Scilly’s! Harbour porpoises were seen speeding through the tidal races often exposing their bodies whilst leaping into yet another wave and there were many gannets feeding in these waters too.
Leaving the Scilly’s behind we witnessed large flocks of gannets who appeared to be nervously searching for something…… when we suddenly saw a huge blow of a large whale, soon followed by another whale blow. We believe that the whales were probably fin whales. Unfortunately, with the westerly winds picking up it meant that the swell was building up too and we did not get any better views of the whales.
A bit closer to Land’s End we saw another blow and this time were able to identify the whale as fin whale. The animal was not fully grown and the spouts were not as big as the ones we had seen closer to the Scilly’s. It was probably a juvenile who had ventured a bit further away from his/her relatives. Fin whales have excellent hearing and communication skills and it is not uncommon for this species to be so widely spread-out.
Approaching Gwennap Head we were pleased to see porpoises feeding in the tidal races. The gannets were also present again and perhaps it was a difference in the tidal state that can best explain their absence here the day before? Compiling more data will give us a better picture regarding the habitat-use of dolphins and porpoises in these waters.
1 March 2008
Unfortunately, we were not able to conduct our research during the last week due to unpredictable weather conditions and fog. However, I just received an e mail from the Captain of the Gry Maritha informing me that they saw the three fin whales over the weekend! This is very good news. The crew of the Gry Maritha will continue to note down the positions of sightings which will contribute to our knowledge of the distribution of not only whales, but also dolphins and porpoises.
Our winter research is already coming to an end. We are going to present our findings to the Annual Conference of the European Cetacean Society. There will be over 400 people from over 30 countries present!
We have joined forces with David Ball of the Silver Dolphin Marine Conservation and Diving Centre (Trinity House Buildings, Penzance). David together with the help of volunteers and students will take the lead continuing to collect data on marine mammals aboard the Scillonian, which is scheduled to set sail this month. We have provided necessary training, survey sheets and scientific research protocols which will allow us to continue to monitor the distribution and diversity of marine mammals in these waters year-round!
Watch this web-site for updates!
Marijke de Boer
2007 Marine Life Surveys aboard Scillonian III
Biology staff from the University of Exeter, Cornwall Campus (UEC), in association with the Isles of Scilly Steamship Group, carries out fortnightly ferry surveys for marine megafauna between Penzance and St Mary's, aboard Scillonian III. For more information download a PDF file here.
UEC, in association with the Marine Conservation Society (MCS) and Cornwall Wildlife Trust (CWT) also carry out a monthly aerial survey of the coast of Cornwall, from Newquay (north coast) to Land’s End around to Falmouth (south coast). On both the ferry and aerial surveys, researchers record all cetaceans (whales, dolphins or porpoises), basking sharks, seals, turtles and sunfish sighted. Although these animals have been sighted in the past around Cornwall, some are more common than others. E.g. basking sharks and bottlenose dolphins are regular visitors in the summer, and sunfish, although more frequently found in tropical waters, are now recorded. We also record the occurrence of jellyfish, as these organisms are an important food for the giant leatherback turtles which sometimes visit our shores.
Many of the species we observe are in need of conservation or protected by law. E.g. harbour porpoises and bottlenose dolphins are listed in the EU Habitat’s Directive, this means they have protected areas called “Special Areas of Conservation” in UK waters. With the data collected, we will be able to better understand the distribution of marine wildlife in the waters around Cornwall, to look for times of the year, and areas which are important to these exciting creatures.
JULY AND AUGUST 2007
On our July 18th survey, we had a sighting of two harbour porpoises on the morning trip to Scilly, and two porpoises on the return sailing, along with several blue jellyfish.
UEC also continues to carry out monthly aerial surveys of the Cornish coast. On July 20th, we had perfect conditions for sighting marine life, but recorded only a single sighting of a basking shark, and three grey seals. This is certinly a contrast to this time last year, when we recorded large numbers of basking sharks and sunfish around the coast.
On our most exciting survey of 2007, on August 10th, we sighted a total of 18 basking sharks, 9 common dolphins (including a calf) and a sunfish. It's good to see a return to the numbers of basking sharks recorded last summer, even if it's a little later this year!
A survey on August 17th resulted in the most basking shark sightings of any survey we have run to date - 34 individual sharks were sighted! Many were actively feeding and were concentrated along clearly visible fronts in the water. A large group were present off Land's End, and numerous small groups were spotted along the south Cornish coast. We also counted 25 grey seals, hauled out at Godrevy.
UPDATE 1ST NOVEMBER 2007
The University of Exeter, Cornwall Campus carries out regular surveys aboard the Scillonian III. On the most recent survey, on October 31st, a group of around 25 common dolphins were sighted feeding energetically, not far from the Isles of Scilly. Two harbour porpoises were also spotted near to St. Mary's. On the return trip, several groups of porpoises were sighted.
The ferry stops running for the winter, this Saturday, so this was our last survey of the year. Many thanks to the crew of the Scillonian III for accomodating our surveys and for the enthusiasm they have shown in collecting additional sightings data for this project! Thanks also to our volunteer surveyors, especially Dan and Leslie Jarvis. We are also grateful to the Isles of Scilly Travel company, for sponsoring this work.
ACKNOWLEDGEMENTS
We are grateful to Isles of Scilly Travel, the pilots and crew at Skybus and especially to the crew of the Scillonian III, for facilitating us on board . For further details please contact Ruth Leeney: r.leeney@exeter.ac.uk or find out about all the biology carried out the UEC: www.uec.ac.uk. This work is funded by the European Social Fund.
Ruth Leeney, University of Exeter 2007
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