Studying Perth's Dolphins
Victoria Gill headed out onto the water with Murdoch PhD student Delphine Chabanne to find out more about the population of dolphins living in Perth River.
Delphine - Hopefully, we're going to see some dolphin upstream, so we just came back from downstream and we didn't see any, but the Swan and Canning River in fact is big enough to have a chance you'll see them today.
Victoria - Exciting, right! Well, let's go.
Delphine - So, using the dorsal fin and photo identification, we can recognise each individual so that we know which individual associate with another one. The bottlenose dolphin associates with a typical individual. Generally, you will see a group of male together and a group of female with calves together. So, that is something that I'm looking at. First of all, we are trying to... ah, we have dolphin.
Victoria - That's amazing! Wow! So, how many can we see.
Delphine - At least 4 of them, maybe 5.
Victoria - And you said we've got Gizmo. I guess Gizmo is a bit of a celebrity.
Delphine - Yeah. Gizmo, it's a calf. It's very easy to recognise because this calf was unfortunately entangled last year by a fishing line around his dorsal fin. It took us, the Department of Environment Conservation and the Police Marine and the work from all of the community a bit of time to be actually be able to disentangle it. But he's recovering very well even his fin has been well-damaged. It's always very great to see this little boy actually.
Victoria - Can you just describe where we are Delphine, because this is an amazingly urban, well suburban, I suppose, site to be spotting big marine mammals like this. So, where in Perth are we?
Delphine - So, we are in the freshwater bay, just north of (29:35). So, here it's a marina and that you will very often seen there's dolphin in this area as well.
Victoria - What's good about this area for them?
Delphine - At the moment, they're actually foraging and socialising between the cows. So, I guess it's a very good spot for feeding.
Victoria - So, when you spot them, what's the sort of process that you go through to gather your data?
Delphine - So, we basically mark a location to spot them on the map. We're also taking photo of their dorsal fin so that we can recognise them individually. We're looking at their behaviour so that would be resting. In that case, it's foraging/ socialising for the calves and you also look at - so, when you look at the composition, that would be mother and calf, and you try to check out the distance between the mum and the calf basically.
Victoria - And you're taking the photos to keep a log of what their dorsal fins look like because that's how you identify them isn't it? You look at the different shapes and notches on their dorsal fins.
Delphine - Yeah, that's right. So, we're looking at the shape of the dorsal fin, but also, any nitch and notch on the fin which is actually what we're using to identify them.
Victoria - What sort of challenges do they face, living in an environment like this? It's quite a busy marina around here. We're surrounded by the suburbs. There's a lot of activity, lots of boats, lots of fishing. How challenging is it for these dolphins to live in an environment like this?
Delphine - Well, you basically see everything - a lot of boats, you also have a lot of fishing, so it's a lot of fishing line say, in the water unfortunately, and so, the dolphins are in a very high risk to be entangled by a fishing line. So, it would just be stuck and start cutting a bit more or even deeper and get infection, and just touch the whole health of the dolphin.
Victoria - What do you hope, what information you'll be able to find out that'll help protect these animals by studying in the way that you do?
Delphine - Well, first of all, trying to looking at which habitats the dolphin area, the dolphin are using the (32:02) river would be very good things to monitor, both recreational and any other activity in a typical area. Secondly, we're trying to and it's not trying, it's all the time, pass the message to everyone, asking to take their rubbish out.This is one of the major issue in an urbanised area, hard to control, and if no one is doing anything, it will be just be (32:32)
Victoria - So, you're trying to spread the message about people not leaving fishing equipments and rubbish, and other things that they might be able to ingest or get tangled up in in the water.
Delphine - That's right.