Thursday, January 22, 2009

Dispatches from Djibouti.... 6. The last few days at Djibouti...

Well our return to Ras Korali was welcomed with a flurry of sharks feeding off Acacia beach in the late afternoon, a pattern that seems to be the norm on this trip. As the expedition is drawing to a close we are slowly coming to grips with the fact that in a few days time we will be back in our respective homes with many of us returning to the European winter with temperatures of somewhere just above zero if that!

The trip has been a great success as far as data collection is concerned... we have logged over 500 in-water whale shark encounters in the 11 days so far with one day still to go; we have currently 115 new sharks identified and added to the database but this is only based on sightings for the first seven days as the photo matching has had to take a back seat to data collection. We have also resighted a number of sharks from previous years including Shiraz, the shark we fitted with a satellite tag in 2006.

Shiraz in 2006 fitted with a towed satellite tag, photo Simon Rogerson.

The sharks we are seeing have been predominantly small juvenile males with many below 3 metres in length and very few greater than 5 metres, the largest being a 7 metre male; as such this is almost certainly an aggregation of very young juveniles but the lack of large adult sharks and in particular pregnant female sharks raises questions as to the area being a pupping ground for the species as has been suggested.

The environmental monitoring has also gone well with a whole swath of plankton samples being collected for analysis as well as matching CTD profiles of the area, although an initial look at this data has suggested that there is very little temperature change from the surface to 50 metres depth... Gavin from the BBC let us attach the CTD to his ROV to get some deeper profile data but even at 70 metres the temperature remained at 25.3’C.

Both PAT tags have been deployed and the local live-aboard boats have all been told about them and will make sure that they are not disturbed by their clients, in fact all were very interested in the programme and promised to send us additional photos for the photo ID database.

Dan Beecham had been beset with problems with the HD video camera housing developing a leak in the first week but this was cured by a replacement housing being shipped over and he had finally got the footage he was after of the whale sharks feeding at night in the flood light off the stern of the boat. Tom Peschak also seemed quietly happy with the images he had captured although there was always another slightly better shot he just could get if only...

As for the eco-volunteers who had joined us, all seemed to have enjoyed the experience, even if they weren’t sure exactly what they had signed up for at the outset! Everyone had soon worked out what bits of the process they were most interested in and all contributed wholeheartedly and no-one shirked their share of the paperwork... thanks all for a great job well done!

One shark in particular had caught our attention over the weeks and given us cause for concern, a 5.5 metre female shark that had a thick rope tied around her tail... we have no idea how long the rope had been attached but it had cut deeply into the top and bottom of her tail and several attempts to remove it over the course of the trip had failed.

With the satellite tags attached, David set this as a goal and had borrowed a serious pair of wire cutters from Captain Armand to try to remove the offending rope.... and the 13th of January proved to be a lucky day as Katie found the shark and David was able to cut through the rope and remove it carefully from around the shark, his good deed for sharks for the week!

And so it is with mixed feelings that we head back towards Djibouti aboard the Deli: on the one hand the expedition has gone very well and we have largely achieved what we had hoped to, on the other the joys of the Northern hemisphere winter and thoughts of weeks of work completing the photo ID analysis is a bit daunting!

Once in port the Deli is immediately invaded by Captain Armand’s excited young children and soon everything is a flurry of activity as equipment is stowed away for the home-bound flights....

Dan seems to have accumulated even more baggage and knows that somehow everything does indeed fit into the myriad of boxes that are amassing on the quay side...

One day left to visit some of the other sites in Djibouti!

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