University of Queensland researchers have found bottlenose dolphins in Moreton Bay off Brisbane could be teaching other dolphins to 'beg' for food from recreational fishers, with the behaviour creating short and long-term risks.
Dr Léonie Huijser from UQ's School of Veterinary Science made the surprise discovery as she investigated the social structure of Moreton Bay's population of Indo-Pacific bottlenose dolphins for her PhD thesis.
"Within the dolphins' social network, I found a cluster which would consistently patrol moored boats, waiting for recreational fishers to illegally toss them discarded bait or catches," Dr Huijser said.
"Fishing is popular in the bay and it seems some dolphins have learnt to exploit it."
Dr Huijser said the begging behaviour was dangerous for the dolphins, and she was concerned it could spread throughout the population.
"Dolphins learn behaviour from their peers," she said.
"If these 'beggar' dolphins start to associate with 'non-beggar' dolphins, the behaviour may spread rapidly, making it a population-wide problem."
Pods of dolphins displaying these behaviours have also been sighted off Bribie Island and North Stradbroke Island.
"Some of the dolphins who boldly approach boats have evidence of propeller strike and fishing line entanglement," Dr Huijser said.
Dr Huijser says there have already been instances where dolphins are struck by propellers and entangled in fishing nets. Image: Jake Linsky
Image: Dr Leonie Huijser
Dr Huijser says there have already been instances where dolphins are struck by propellers and entangled in fishing nets. Image: Jake Linsky
Image: Dr Leonie Huijser
"During one of my first fieldwork days near North Stradbroke Island, a dolphin surfaced next to our boat but disappeared once it realised we weren't going to feed it.
"Its fin had been badly mangled previously, indicating it may have been caught up in a line."
Professor Michael Noad supervised Dr Huijser's research project, and said her findings show how adaptable bottlenose dolphins were and how this influenced their social structures.
"Not all adaptations are positive and begging is an example of an adaptive strategy that may have short-term gain but long-term risks," Professor Noad said.
"Dolphins risk becoming reliant on donated fish, which is like junk food to them - quick and easy, but unhealthy.
"It may lead to food poisoning or nutritional imbalances."
Professor Noad said better policing of illegal dolphin feeding in Moreton Bay was needed.
"Dr Huijser's findings should be used by wildlife rangers to increase awareness through a public education program around the potential negative effects of dolphin feeding," he said.
Dr Huijser is planning further surveys to inform authorities about 'begging hotspots'.
The thesis has been published on UQ Library's eSpace.
