by Levina Mahendran
With questions being raised about the environmental health of the Swan River and its aquatic life, one species in particular in often forgotten: the Bull shark.
The Swan River is used by Bull sharks as nursing grounds, between the months of October and February.
There is currently no information on how many Bull sharks return to the Swan River each year to give birth.
Dr Rory McAuley from the Department of Fisheries WA said Bull sharks are not a primary focus for environment researchers and marine biologists.
“Bull sharks are a sporadic occurrence in the river. They are born in the river, and live in the river for roughly five years before they find their way back to the sea,” said Dr McAuley
“They do not seem to be severely affected by the health of the river – probably because they are very resilient and adaptable.”
In 2011, researchers from Murdoch University came across three juvenile Bull sharks while conducting research for The Estuarine Health Index Validation Project.
“They were caught by researchers who were trying to determine indicators of the river’s health. Bull sharks are not good indicators of estuarine health because they only reside in the river for a short period of time… in simpler terms they are just visitors to the Swan River,” said Dr McAuley.
Swan River’s Bull sharks have also been caught for sport, however, very few avid fishers target them.
Jon Hammond from Hotbite by Compleat Angler Nedlands said that Bull sharks are elusive and hard to target.
“We don’t target Bull sharks, very few people do. They are hard to spot and to be honest there are better locations to hook them, like Collie River or in the canals over in the eastern states.”
Mr Hammond said the last Bull shark caught by recreational fishers was in 2011. The juvenile shark was caught in shallow waters near the Swan River Estuary Marine Park, and was approximately a metre in length.
Dr McAuley said although fishing for Bull sharks is not illegal, people using the Swan River for recreational reasons should be aware of Bull sharks even in shallow waters.
Shark sightings should be reported to the Water Police on the 24 hour hotline, 9442 8600.