Wow, Wow, Wow! It has been a busy few weeks since I arrive in Perth. First it was non-stop preparing equipment and organising ourselves and then it was diving head first into Bremer Bay life and data collection. We arrived in Bremer Bay in Western Australia on the 8th February and were out on the water 7.30 am on the 9th.
We are here to collect data on this unique aggregation of killer whales (Orcinus orca) that occurs every year between January and March a 2 hour steam offshore from Bremer Bay where the water depth drops quickly from around 80 metres to over 800 metres and deeper. Here there are numerous underwater canyons where the depth can reach 3000 metres or more.
Now back to the cetaceans…So very little is known about the Australian killer whale population and we hope to be able to change this by building up a picture of where they are, and what they are doing, while also deciphering the individuals we are seeing through fin identification and using hydrophones to determine their acoustic repertoire. It is an amazing project.
On the 10th February we deployed two noise loggers which, are long term underwater recording devices that record on a schedule and allow us to build a picture of what is happening when we are not there through the acoustics of the region. From these we will be able to build a picture of natural ocean noise such as waves, wind and, marine mammals as well as anthropogenic noise from boats and far off seismic activity.
Alongside, the data collection on marine mammals we also plan to use a mounted sonar to record the biomass in the region especially when marine mammals are feeding and a CDT (Conductivity, Depth and Temperature) instrument to record salinity, depth, temperature as well as fluorescence to gain a better understanding of what makes the ecosystem work. Further, to all this amazing equipment we have also had sonobuoys donated to us by L3 which, will allow us to passively and in real-time monitor the acoustic environment while we are at sea. This will in theory enable us to hear what is happening underwater while we see what is happening above water and potentially determine what we are missing as well as what is happening (acoustically) up to 5 km away.
We are only just getting started on this project but, from it I hope to be able to build up a PhD thesis that I can really get excited about. Alongside killer whales there have been sightings of beaked whales, sperm whales and pilot whales in pervious seasons. Just yesterday we spotted a pod of between 20 and 30 long-finned pilot whales (Globicephala melas) where it looked like the sea was bubbling with activity. I cannot wait to see what tomorrow brings.
We had a windy day off today where we tried to catch up on some data, visited the beautiful remote beaches of Western Australia and do all our laundry which, was nice especially as we don’t know when we might get another day for data catch up!
I will try and upload some video footage and updates from the field as our crazy hectic time here in Bremer Bay flies back.