Thursday 25 February 2010

Hydrophone deployed at Sandwich Harbour!

We’ve been wanting to do some work down in Sandwich Harbour for a while now and eventually managed to get there today by boat. Sandwich Harbour is a similar, but shallower embayment ~50km south of Walvis Bay. Although it used to be deep enough for ships to sail into it and refill their water supplies, the movement of the dunes and erosion by the sea has made the whole bay much shallower, the mouth narrower and dug considerably into the dunes which lie alongside the sea. To illustrate how dynamic an environment these sandy coastlines are here – the GPS map was WAY off down there and indicated us being on land on several occasions.

The attraction of this area from our point of view is that there is almost NO human activity in the area (barring a bit of light fishing and the occasional weekend boat), which makes it a very interesting comparative site to Walvis Bay with its harbour, tourism and aquaculture – are the animals using the area differently down there? We hope that a month of a hydrophone logging the presence and absence of the dolphins in the area will gives us some indication of their habitat use patterns in the absence of human activity.

We looked at various options to get down there including towing the boat down the beach, borrowing a smaller boat to tow or using a bigger boat which we could stay on. I briefly flirted with the idea of buying our own catamaran, but then remembered I’m a scientist not an internet millionaire. So in the end, the quickest and easiest way was to drive down the coast with Nanuuq and back. It’s a very long way (the GPS track showed 84nm total for the day – I won’t tell you how much fuel we used, it makes me feel a little bit sick) along a very exposed and lonely section of coastline. We had really hoped to stay over there and send fuel down by car and then be able to work for two days in the area to allow us to do some more exploring and photo-ID work, before heading back up and thus make the most of the fuel use. Unfortunately the Ministry of Environment (MET) wouldn’t give us a permit to stay over, merely to enter the area (it is part of the Namib Naukluft National Park).

So with the wind picking up quite strongly every afternoon here, we were on a pretty tight time schedule and had to leave Walvis at 6am and head straight down there only recording dolphins as we passed. But the good news is that the weather held out all day, we got the hydrophone in the water (red star on map) and back home safely before the wind picked up! Not many dolphins to report unfortunately, a few small groups of Heaviside’s in the mid-section of the trip (the blue dots on the map) but a good day all round. The white bar on the map indicates 50km

Moving house tomorrow and then back on the water on the weekend.

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