Wednesday 18 March 2009

Walvis Bay - there's always something new. Just as i was getting used to the tame seals, boat friendly pelicans, semi-resident humpback whale (the little scarred individual we first saw on the 17th Feb is still here one month later) and dolphins that feed in hip deep water, something really interesting happens.

On Monday , 19 bottlenose dolphins (roughly 1/4 of our entire study population of 70 odd!!) got themselves stuck up the inner lagoon on a dropping tide and were stranded for the entire day! Where was I? 400km away in Windhoek for the day with car problems! The bottlenose dolphins have been stuck up this lagoon as well as in Sandwich Harbour on several occasions before, but to my knowledge, never this many animals at once.

Megan Dreyer of Mola Mola tours called me with the news and I although I couldn't be there, many other people were able to attend including many of the owners and guides from the tour companies, John and Barbara Paterson, Caroline Weir who has been working with me for a few weeks and Heidi Skrypzeck from the Ministry of Fisheries. The community was amazing - it's great to see so much interest in marine wildlife and we can only hope that this type of event has positive knock on effects for marine conservation initiatives in general. The only downside was that at times there were too many people in the water with the dolphins and more central control and guidance was needed. The development of a more formalised 'strandings network' will definitely help in this regard. Working with the local community to develop the existing network and help with training, communication and networking is one of our goals for this project.

Back to the dolphins - it seems they had trapped themselves in the shallow end of the lagoon on a dropping tide but were otherwise healthy individuals. All the people that attended did a great job of keeping the dolphins cool and wet and generally calm. Of 19 animals identified from photographs (including 3 calves) after the fact, all were released successfully as the tide came back in with the exception of the smallest calf which unfortunately died in the afternoon (probably from stress given the situation). Most animals were reported to be generally very calm. Only one animal was extremely agitated all day and kept falling on it's side and battling to breathe. In the end this animals also was released.

On Tuesday, the day after the main stranding event, one animal (tagged with number 203 by the Ministry during the stranding and given number T-012 from natural marks in our catalogue from last year) restranded far into the lagoon. Unfortunately we were at sea at the time and although we tried to find a group of bottlenose dolphins which had been reported in the bay so that the stranded animal could be released in their vicinity, we were unable to track them down as they seem to have passed around the point into very rough waters. Going through my catalogue now - we identified this animal (T-012) as a mother last year, but I can't match the animal we had identified as its calf to the photographs from Monday (calves aren't very well marked at all so it's very difficult to re-identify them without a continuous set of images as they grow). It is possible that this animal was the mother of the calf that died. Bottlenose dolphins have been reported to show very clear mourning behaviour including carrying dead calves around for several days after they have died and this may explain why it came back to the lagoon after the initial rescue.

Naude Dreyer (Mola Mola / Sandwich Harbour tours) and John Paterson were able to attend and coordinate a rescue. The decision was made to relocate the animal out of the inner lagoon area. With help from Namport (the port authority) the dolphin was moved (across several hundred metres of knee deep mud) using a cargo net, ground sheet and air mattress onto a pickup and moved across to the north side of town an released just north of the harbour breakwater (since we couldn't find any other animals). Upon release, the animal took a minute or so to orient itself and then shot off northwards. Although we were only a mile away at the time of release in Pedro, we were unable to find the dolphin at all and we all hope it won't re-strand. We're still at sea for a few more days this season and I hope we can reward all involved with at least a confirmation of this photo of this dolphin swimming free again.

This evening, (48 hours post stranding), Naude called me to let me know that he had seen 3 tagged animals in a group of 6 down near Sandwich Harbour this morning. They were feeding, chasing fish and moving very rapidly southwards in a fairly rough sea. So, other than the one calf death, it seems that all the other animals are none the worse for wear after their misadventure.

Photos below by Caroline Weir showing a few scenes from the stranding and a shot of animal T-012 (tag 203) that restranded the day after the event and Wally (Mola Mola / Sandwich Harbour tours) looking after the very stressed animal and trying to keep it upright so it could breathe properly.

Monday 9 March 2009

Our fundraiser was held on the 3rd at the Anchor's restaurant thanks to the Dreyer's of Mola Mola and went off very well. Thank you to everyone who came, there was quite a nice mixed turnout of skippers, tour boat operators and various other interested people. And a very big thank you to those who supported our research with donations, especially the tour companies who made larger donations - it's really made a difference to the number of sea days we're able to get out there now. Also a thank you to John Paterson, who kindly gave us all ten minutes on his very important work (see the albatross link to right) with sea birds to split the dolphin talks and help support our project!

We were out almost everyday last week trying to make the most of having three of us on the boat. Caroline Weir of Ketos Ecology ( has joined me for a few weeks on her way through to an offshore job in Angola and overlapped with Tess Gridley for a week, who has just left for Plettenberg Bay in SA to collect more bottlenose dolphin whistles with Vic Cockroft's lab down there. Just want to say a quick thanks to Tess for coming through and helping me out and I'm sorry we couldn't get you more whistles - you'll just have to come back in winter when they're more abundant! This was the first external collaboration for the project and I hope we'll be able to support many more in future - I certainly learnt a lot from having an acoustics person on the boat and we're currently working on trying to get a paper out of what we have recorded, so it was a productive visit.

We've had a few good dolphin days out there with the Heaviside's in particular being more abundant in the last week, but they were scarce at the point again today. Saw our first dusky dolphins today in the middle of the bay - just a small fast moving group of 3 which we unfortunately lost quite quickly. In my last post I mentioned the bottlenose feeding in the lagoon. When we launched the next day the dolphins swam right past the slipway and we got in a really long focal follow on them all the way around the south of the bay, around the point and down to Donkey Bay where we left them. They were feeding quite a lot in the bay but largely just pottering along once they got past the point. See photo of them feeding in proximity to some local fishermen and a great shot that Tess got near Donkey Bay of a younger animal jumping.

Monday 2 March 2009

What news from Namibia? Thing have been perking up here which is great. The Heaviside's were fairly abundant at the point for a few days over the new moon period, but were difficult to find today again, although it was quite choppy out there.

Highlights of the last few days? On a long survey up to Swakopmund yesterday, we resighted the small, scarred humpback whale I mentioned in my previous post, and only a kilometer from where we saw him on the 17th! I've never known a humpback whale to stay in one place for so long. Although it is 'out of season' now and they should theoretically be feeding in the southern ocean, so it's hard to tell what is motivating them right now. Although there was a large group of birds circling it when we first saw it, we didn't see anything that could be definitively described as feeding behaviour from the whale.

After a slow start to today with a some dark, choppy weather and impossible to find Heaviside's, we managed to track down the bottlenose dolphins (thanks to the tour boat skippers). They were in the inner lagoon, where they had been seen yesterday afternoon. This is right next to the yacht club where we launch and the Raft which is a great local pub with a lovely sea view and wonderfully cheap beer (which, given the current water shortage in Walvis Bay is the cheapest thing in town to drink).

The bottlenose dolphins in Namibia come into ridiculously shallow water. We spent the whole morning sitting inside the inner lagoon in water that was only just deep enough for the boat and trying to get recordings of their whistles without dragging the hydrophone (or the boat) on the sea bed. The lagoon is a RAMSAR site so boats aren't allow to go in - but it's so shallow and full of sandbanks you couldn't even if you wanted, although the dolphins managed it. The dolphins were feeding on some of the hundreds of mullet that were schooling in the lagoon and we got some great shots of them pinning the fish against the shore using a 'pincer' manoeuvre. One or two animals would chase a school of fish along at the surface (it was so shallow there was nowhere else for them to go) and a third animal would circle around to the front. As they the dolphins met, all the fish would jump out the water (see pics). I've never seen such obvious cooperative feeding before so it was a great sighting for me and we got some good data from this group, both behavioural and acoustic.