“The Fremantle Doctor”, a challenging sea breeze for conducting field work during the summer months around Perth.
The Coastal and Estuarine Dolphin Project (CEDP) aims to ensure the long-term conservation of bottlenose dolphins in metropolitan waters of Perth, Western Australia.
Our study area contains four sampling regions: Cockburn Sound, Owen Anchorage, Gage Roads, and the Swan-Canning Estuary.
Every season (i.e. winter, spring, summer, autumn), we aim to survey each of these regions 5 times. Transect routes have been designed for each sampling region to maximise coverage of the region and its habitats.
Unfortunately, our field work is dependent on the weather conditions. In summer, Perth is affected by an afternoon sea breeze starting by noon and blowing from the southwest direction between 15 and 20 knots. The “Fremantle Doctor”, as the breeze is known, arises from the temperature differential between the land and the ocean.
However, while most people appreciate a cooling visit by the Doctor on a very hot day, the Doctor is not so favourable for boat-based photo-identification research. Sea conditions are much harder and visibility much less when the Doctor is in.
So far this summer, we have completed 4 cycles (1 cycle consisting of one survey of each of the four sampling regions) for the summer season. In the offshore areas (Cockburn Sound, Owen Anchorage and Gage Roads), we have encountered 10 groups of dolphins (between 4 and ~12 individuals including calves). To conclude sampling for this summer season (December – February), we are hoping to do two cycles more by the end of the month.
In addition to the normal pattern of cycles, we surveyed the Swan-Canning Estuary 13 more times during this season. During these surveys, we identified 31 dolphins (including 9 calves).
Nine of these 31 individuals were seen only once. Three of the mother-calf pairs were also observed in the sampling regions outside the estuary. These supplementary surveys in the estuary will help us to evaluate the status of the community of resident dolphins associated with the Swan-Canning Estuary and where six dolphins died in 2009. For more information about this case, you can look at the Technical Report prepared for the Swan River Trust in 2010.
This research is made possible through the support of a variety of corporate, government, and community partners including volunteers from the Dolphin Watch project, Fremantle Ports, and the Swan River Trust.