BRAHSS 10-11 Overview
The first two years of a large, four-year collaborative study, BRAHSS; investigating the effects of seismic airguns on the behaviour of humpback whales during migration is led by the University of Queensland.
Field work operates from Peregian Beach on the Sunshine Coast where the University of Queensland has conducted several smaller studies previously on humpback behaviour and the effects of sound.
The site is ideal for small scale observations as the whales migrate close to shore and can be observed and tracked from land stations at elevated points along the coast. This allows us to look at the movements and behaviours of many whales at one time. We also moor several hydrophones off shore and these are radio-linked back to a base station where we can track singing whales acoustically as they move along the coast. By overlaying the acoustic tracks on the visual tracks from the land stations, we can get a very detailed picture of the natural interactions between the whales.
In 2010 we will visually and acoustically track whales as they move down the coast. During our experiments we towed a single airgun through the area from a large 20m fishing boat. This airgun may or may not be firing so that we can compare the behaviours we see in each situation to try and determine how much of the reaction was due to the airgun and how much was just due to the vessel moving past the whales.
To learn more about the whales and their reactions, we will also be trying to attach DTAGs to some of the whales. These measure high-resolution movements, dive depth and vocalisations of the whales over several hours while they are underwater and so provide an excellent record of behaviour while they are not visible to the land based observers.
In 2011 we will use four airguns to do a further series of experiments. This group of airguns will be louder than the single airgun and so, by comparing reactions to this airgun array with the single airgun used in 2010, this will allow us to look for whether or not the whales are reacting to how loud the airguns are or to how close they area. As well as the high resolution tags mentioned above, we will also be using some satellite tags that also measure dive profiles and movement over a week or so to allow us to look for evidence of longer term behavioural changes.