Australian researchers have for the first time documented the unique riskyfeeding behaviour known as ‘strand feeding’ in Australian dolphin s.
Southern Cross University researcher Dr Daniele Cagnazzi used drones to film apod of humpback dolphins in the Fitzroy River – one of Queensland’s largestcatchments – to document young and adult dolphins ‘stranding’ or ‘beaching’themselves to catch their next meal.
Dr Cagnazzi has studied the species at Fitzroy River in Central Queensland for13 years using photos, videos and genetic testing to observe the species.
“Strand feeding occurs where dolphins patrol the mud banks in search of aprey; once the prey has been localised a dolphin swims at high speed towardthe shore, catches the fish in its mouth and remains stranded for a short timebefore sliding gently back into the water,” he said.
“This type of feeding is very risky, as dolphins run the risk of remainingstranded, however, since this behaviour is routinely repeated it must providean important proportion of their daily feeding needs – dolphins must consume4-6 per cent of their own body weight in fish each day.
“This feeding only occurs at low tide when the mud banks are exposed,therefore, habitat modification change, increasing flood frequency andsedimentation may affect the ability of dolphins to strand feed to providetheir daily food needs. This is something we will continue to monitor.”
Dr Cagnazzi said dolphins around the world have shown different feedingstrategies and until now strand feeding had been documented in very fewlocations internationally and primarily to bottlenose dolphins.
The Fitzroy River is the only known location where Australian humpbackdolphins are known to display this behaviour reliably.
“This strand feeding behaviour is conducted primarily by a very well-knownfamily group of humpback dolphins who we’ve identified as long-term residentsin the Fitzroy River,” he said.
“The number of dolphins involved in a single episode varies from one to twowhile the rest of the group is busy in other activities and strand feeding canbe full body or partial.”
Australian humpback dolphins are listed as ‘Vulnerable’ in Queensland and inthe International Union for Conservation of Nature ‘Red List’ of threatenedspecies. Dr Cagnazzi says relatively little is known about their ecology.
“From here we are aiming to use the analysis of photographic and genetic datato determine if this strand feeding behaviour is culturally transmitted fromthe mothers to calves,” he said.
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