By Paddy O’Dwyer
basking shark research assistant
A sunny day with only a light breeze and calm seas for most people might mean a trip to the beach. For Simon Berrow, Nick Massett, Sean Mac An TSithigh and myself (Paddy O’Dwyer) it meant the perfect opportunity to tag and collect mucus (slime) from basking sharks off West Kerry. The Irish Basking Shark Project has been running for quite some time now with great success in many areas mainly Kerry and Donegal. We started early and loaded up all the gear we needed for the day. Once loaded we departed from Ventry pier and didn’t have to wait long for our first sign of wildlife because we spotted some common dolphins just outside Ventry harbour.
We encountered our first sharks at Slea Head, the first 3 sharks disappeared beneath the surface before we could approach close enough for tagging or sliming. Despite our efforts to wait for them to reappear there was no sign. A feeling that this was going to be a long and frustrating day was beginning to seep in. However our fears were soon allayed as we began to see a few more fins in the water east of Beginish. A short time later having successfully tagged and slimed our first few sharks the tensions on the boat was alleviated and everyone began to enjoy what was really a fantastic day on the water.
Shark fins were appearing at the surface in every direction we looked with upwards of 6 separate animals visible on the surface at times. As the day wore on Nick spotted a breaching shark while the rest of us only managed to see the remnants of the splash. We began to notice that we had tagged and slimed most of the sharks in this area with our green tags placed at the base of the dorsal fin. At this point in the day it was time for us to enjoy a quick sandwich and take over boat duties, because Nick was going to use his Go-Pro camera to try and ascertain if the sharks were female or male. This is an important part of the research as analysts have yet to identify the genetic markers in the slime that identify if a shark is a male or a female. Currently the only way to identify the sex is by the presence or absence of claspers. We would record the tag number and then use the camera to capture images of the shark's underside to identify if it had claspers or not.
The theory is that by knowing the sex of the animal the slime came from, identifying the genetic markers associated with males and females will be possible. During this period we encountered one of the smallest basking sharks I’ve seen; while most of the sharks we had seen were 5-8 meters, this was a maximum of 2 meters. Little is known about basking shark reproduction so these sightings are all the more interesting. Confident that we had gotten most of the sharks in this area we moved to east of An Blascaod Mór and found yet more sharks. A quick tally at the end of the day revealed we had collected 15 slime samples and 14 tagged sharks. Tagging the sharks ensures that we don’t repeatedly slime the same animal over a day or shark season. It also allows us to track the movement of sharks by identifying tags on subsequent days in different locations. It gives a much better picture of how many sharks are in an area. Since the project began roughly 400 tags have been deployed with up to 15-20 re-sightings of tagged individuals more than a few days after tagging.
The slime samples will be sent to the University of Aberdeen for analysis. The slime has proven to be quite useful as it contains valuable genetic information and can be removed from the shark quite easily without disturbing it too much. Happy with our day's work and some of us needing to make the ferry home, we set about returning to Ventry. On the way we were treated to a breaching basking shark that breached not once but twice. In typical fashion we had already packed away all our gear and cameras. However, sometimes it’s better to witness these things unobstructed and not through the lens of a camera. That said, Sean managed to capture some fantastic footage of basking sharks and will be doing a short feature that will appear on the news during the week. Aside from all our fantastic shark encounters, there were 60-80 common dolphins around the bay all in small groups that approached the boat from time to time. We also saw Minke whales on separate occasions with my best conservative estimate at 3 animals in total. Add to this all the grey seals in the water and our marine species count was at 4. All in all a great day out on the water. If there was a downside, which there always must be I suppose, it was a mild case of sunburn on otherwise smiling faces.
Here is a video report for RTE News of the Day: http://vimeo.com/96538672