Our river at risk

Western Suburbs Weekly - - Front Page - By SO­PHIE GABRIELLE

THE death of well-known dol­phin Gizmo is an in­di­ca­tion that “all is not well” with the Swan River, says his­to­rian and environmentalist Sue Gra­ham-Tay­lor.

Six-year old Gizmo made head­lines in 2012 af­ter Wa­ter Po­lice suc­cess­fully freed the calf from the fish­ing line he had been tan­gled in for al­most two months.

Dr Gra­ham-Tay­lor said Gizmo’s death last month and the deaths of other river dol­phins in the past few years showed that the river was un­der stress. “The pres­sures on the river are both man-made and nat­u­ral,” the Ned­lands res­i­dent said.

Pathol­o­gists at Mur­doch Univer­sity are still in­ves­ti­gat­ing the cause of Gizmo’s death but pre­lim­i­nary find­ings sug­gest he was suf­fer­ing from sep­ti­caemia caused by a long-term in­fec­tion.

Gizmo's gas­troin­testi­nal tract was empty, in­di­cat­ing he had not fed re­cently.

A Depart­ment of Parks and Wildlife spokes­woman said there were signs that the con­di­tion of the river was im­prov­ing.

HIS­TO­RIAN Sue Gra­ham-Tay­lor said Perth’s river dol­phins had be­come an icon of the Swan River but the death of Gizmo last month re­vealed the wa­ter­way was un­der stress.

“Hu­man use in the sub-catch­ments of the Swan-Avon River sys­tem in­creases nu­tri­ents, es­pe­cially phos­pho­rus and ni­tro­gen – that by run-off, through many drains or through ground­wa­ter en­ter the river,” Dr Gra­ham-Tay­lor said.

“We have also lost the river’s fring­ing veg­e­ta­tion as we have re­claimed, straight­ened and walled the river.

“We have cre­ated grassed ar­eas for recre­ation but lost the veg­e­ta­tion so vi­tal for re­duc­ing nu­tri­ents and sed­i­ments en­ter­ing the wa­ter­way, sta­bil­is­ing river­banks and sup­port­ing a va­ri­ety of bird species and other small an­i­mals.”

Dr Gra­ham-Tay­lor said it was im­por­tant to un­der­stand the river’s his­tory in or­der to help pro­tect it.

“An un­der­stand­ing of its his­tory and an aware­ness of the state of the River can help us act to pre­serve and re­store this her­itage icon for fu­ture gen­er­a­tions,” she said.

A Depart­ment of Parks and Wildlife spokes­woman said that in 2009, six dol­phins died in the space of three months but there were signs that the con­di­tion of the river was im­prov­ing.

“Sub­se­quent test­ing re­vealed that a nat­u­ral Mor­bil­livirus was a key fac­tor un­der­pin­ning those deaths,” she said.

“Mor­bil­livirus af­fects dol­phins and other marine mam­mals in wa­ter­ways and oceans around the world and was not re­lated to the health of the Swan River.

“Mon­i­tor­ing un­der­taken with Mur­doch Univer­sity in re­cent years has in­di­cated that fish com­mu­ni­ties are in good to fair shape and there has been an over­all im­prove­ment in es­tu­ar­ine con­di­tion since the mid- 2000s.”

Dr Gra­ham-Tay­lor will present a talk on the Swan River’s his­tory on Novem­ber 25, as part of Her­itage Perth’s Walk and Talk se­ries.

Pic­ture: An­drew Ritchie www.com­mu­ni­typix.com.au d446166

Dr Sue Gra­ham-Tay­lor on the banks of the river in Craw­ley.

Pic­ture: Del­phine Cha­banne

Gizmo the dol­phin.

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