Wednesday 30 July 2008
We had our last day out at sea on Monday, and had a great day out (it's always nice to end on a high note), spotting the bottlenose dolphins, a group of 5 humpback whales well north of town, including a tiny calf probably only days to weeks old and ending with a great few hours with the Heaviside's at the Point, where they were being quite active and boat friendly and I managed snap this photo of them jumping in front of of the the Mola Mola tour boats.
Stranded cetaceans are fairly rare and Namibia has a very large empty coastline, so to be able to effectively find out what animals are stranding and be able to collect data (species, size, age, genetics, stomach contents etc) from them , there needs to be a system in place for reporting their occurrence. This workshop was a first step in getting people interested and letting them know why strandings are important, what kind of data to collect (location, photographs and length) and who to tell so that there is an opportunity for more in depth sampling and that all the data gets centralised.
We'll put up more data on this in a few days.
Thursday 24 July 2008
The weather has been good and the dolphins are still around. Although the Heaviside's seem to be less active and harder to get to around the full moon, we've kept the data collection ticking over. Today, we eventually managed to get the C-POD (the new proto-type version of the moored hydrophone we have at the Point) into the water and hopefully working this time! New technology is always a challenge, but hopefully it gives us a few good days of data. We had bottlenose and Heaviside's swimming right past it this morning just a few hours after we put it in the water, so that gives us some great visual verification of the data it's collecting.
And lastly - we noticed that the guano platform was getting scraped clean when we passed it the other day. This platform was built in the early 19th century for birds to roost on i the hope that they would generate large amounts of guano in an easy to access location that was safe from predators. There are a few of these platforms scattered along the Namibian coastline, but only the one here in Walvis Bay (you can see it on Google-earth on the north east side of the bay very close to shore if you look). They scrape the guano off and then send it across to shore on a wire pulley system. Quite a job!
Friday 18 July 2008
Keith has been an active force in conservation here in Walvis Bay for long time, and was especially involved with the birds and RAMSAR site. He was one of our central contacts here in Namibia and was fantastically welcoming to me when I arrived, showing me around and introducing me to all the relevant people and has recently been helping us by letting us use his computer for downloading hydrophone data, and lending us books from his personal library.
We'd like to pass our condolences to Gail and their sons on their loss. Although we didn't know Keith for very long, we'll all miss him.
Wednesday 16 July 2008
Monday 28th July
At the "Anchor's" (Mola Mola's coffee shop at the jetty next to the Yacht basin)
17h30 - 19h00.
Get in touch with us, if you have any questions.
The PODs have gone back in and come back out as we're still having some teething problems with the newer C-POD's hardware, but the older T-POD is collecting some good data out there.
Ruth and Joaquina setting up the PODs ready for deployment.
One of Jeanne Meintjies customers having a great paddle in a very aptly named boat.
Tuesday 8 July 2008
The big difference between the two species is that we keep seeing more or less the same bottlenose dolphins and have identified very few new animals since mid-June. Whereas, the Heaviside's dolphin catalogue continues to grow. They're much harder to photograph and not nearly as well marked.
I've put up pictures below of our two "star performers": T-029 a bottlenose that we've see a grand total of 8 out of the 13 days that we've seen bottlenose so far and C-022, a very boat friendly and photogenic Heaviside's dolphin that we've now seen on 6 different days!
Unfortunately, C-022's distinctive scarring pattern is already starting to fade so we can only use these scars for a short period. The deeper notches found in the trailing edge of some dolphins are much more stable and can be used over several years to identify animals.
The difference in how "boat friendly" individual dolphins are is a problem for the mark-recapture analysis we're trying to do as, unless we can account for it, we will be severely biasing the resulting abundance estimate (downwards) because we are oversampling some members of the population and undersampling others which are less boat friendly. The best way around this is try to 'capture' the entire population. So...we're back out tomorrow.
Highlights: Despite being a little more choppy than usual due to a northerly wind, the 5th was a nice day out with lots of activity - we had another encounter with a humpback whale off the Point; there several seals were feeding on some large fish out there as well as a few white chinned petrels in the area which we haven't seen too often.
Although the bottlenose dolphins seem a little harder to find this week, we managed an encounter off the Point today (8th) with 5 of them and Mike Lloyd of Mola Mola got a great shot from the beach of us following them down the coast. We were being patient and slowly following them in the hope that they would move out of the surf zone so we could photograph their other side!
Sunday 6 July 2008
The T-POD (www.chelonia.co.uk) is a self-contained, submersible hydrophone and computer which recognises and logs the high-frequency clicks made by dolphins. These "echolocation" clicks are used by dolphins (and porpoises) to explore their environment, find prey and communicate.
This screenshot from the programme TPOD.exe shows a 4-second period in the early morning of June 30th. These clicks were recorded in the frequency range between 90 and 130 kHz, indicating that they are clicks from Heaviside's dolphins. Time is shown on the x-axis and the y-axis shows Pulse Repetition Frequency, or click rate. The red and yellow lines probably represent clicks from at least 2 dolphins, since one series of clicks appears to be increasing in speed, whilst another series (the yellow and red line on the bottom right of the screen) is slower.
This is the first use of T-PODs to acoustically monitor Heaviside's dolphins! Watch this space for developments and more detailed findings......
Many thanks to Dr Simon Northridge at the University of St. Andrews for the loan of this equipment.
Tuesday 1 July 2008
We're taking most of this week off to take care of a few logistic issues but will be back on the water on Friday