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.

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