Fish flour­ish from flows

The Weekly Advertiser Horsham - - 2017 In Pictures -

Re­searchers have dis­cov­ered a spike in Wim­mera na­tive fish num­bers in­clud­ing a rapid spread of the pre­vi­ously de­clin­ing South­ern Pygmy Perch from the Grampians all the way to Hor­sham.

Wet con­di­tions dur­ing the past two years, com­bined with reg­u­lar en­vi­ron­men­tal flows, have boosted fish num­bers in spe­cific wa­ter­ways and al­lowed them to re­pop­u­late ar­eas af­fected by years of drought.

Re­searchers also dis­cov­ered sev­eral River black­fish as well as flat-headed gud­geon in the Macken­zie River down­stream of Grampians Na­tional Park, the first record­ing of the species at this lo­ca­tion for sev­eral years.

The find­ings are in stark con­trast to con­di­tions in the up­per reaches of the Wim­mera River sys­tem north-east of Ararat, where DNA re­search has re­vealed a de­cline in some aquatic species.

Fish ecol­o­gists from De­part­ment of En­vi­ron­ment, Land, Wa­ter and Plan­ning’s Arthur Ry­lah In­sti­tute made the dis­cov­er­ies dur­ing sur­veys for the Vic­to­rian En­vi­ron­men­tal Flow Mon­i­tor­ing and As­sess­ment Pro­gram.

Wim­mera Catch­ment Man­age­ment chief ex­ec­u­tive David Brennan said the re­sults re­in­forced the pos­i­tive out­comes good river flows and habi­tat could achieve.

“Peo­ple who have lived along th­ese wa­ter­ways for decades speak fondly of the fish pop­u­la­tions, and thanks to wa­ter for the en­vi­ron­ment and im­proved sea­sonal con­di­tions, we are see­ing fish species re­turn,” he said.

“The com­mu­nity will be par­tic­u­larly ex­cited about the black­fish dis­cov­ery.

“We are see­ing sig­nif­i­cant en­vi­ron­men­tal gains in Macken­zie River and Burnt Creek sys­tems.

“Dur­ing the past cou­ple of years we have seen the Peron’s tree frog pop­u­lat­ing the en­tire Burnt Creek sys­tem and we are now start­ing to see fish make their way along Burnt Creek and Macken­zie River.

“Over the years, drought con­di­tions and other de­mands for wa­ter meant th­ese wa­ter­ways used to only re­ceive a frac­tion of the wa­ter they needed to sup­port vi­brant and di­verse fish pop­u­la­tions.

“We are very ex­cited about th­ese re­sults. They in­di­cate that wa­ter­way health in th­ese wa­ter­ways has turned a cor­ner.”

Mr Brennan said hav­ing Arthur Ry­lah In­sti­tute un­der­take re­search in the re­gion was vi­tal in gain­ing a bet­ter un­der­stand­ing of the impact of en­vi­ron­men­tal flows.

“It also helps us im­prove tim­ing and de­liv­ery of th­ese flows to achieve the best re­sults,” he said.

Fish ecol­o­gist Joanne Sharley from the in­sti­tute said ex­cit­ing find­ings show­ing the con­di­tion of th­ese wa­ter­ways were con­tin­u­ing on the right tra­jec­tory.

“The most pleas­ing out­comes are re­lated to south­ern pygmy perch, a small-bod­ied species in de­cline across much of their nat­u­ral range in Australia,” she said.

“This species ac­counted for most of the fish caught.

“The mon­i­tor­ing shows they are suc­cess­fully breed­ing in both the Macken­zie River and Burnt Creek and ex­tend­ing their range.

“Their great­est num­bers were found to be where aquatic plants were abun­dant, high­light­ing the value of habi­tat for th­ese fish to breed and avoid preda­tors.”

Mr Brennan said lat­est re­sults were en­cour­ag­ing and pro­vided a clear in­di­ca­tion that hu­man in­ter­ven­tion could have ben­e­fi­cial as well as ad­verse ef­fects on wa­ter­ways.

“It shows that if we didn’t have the use of en­vi­ron­men­tal wa­ter, Macken­zie and Burnt would have sim­i­lar re­sults to up­per lev­els of the Wim­mera River, which has no ac­cess to such a re­source,” he said.

“What we’re find­ing is that we are cre­at­ing a con­nec­tion be­tween the Wim­mera River and the Grampians and it’s that con­nec­tion we would like see go fur­ther up­stream and down­stream in the Wim­mera River. But it’s all about baby steps. There are dif­fer­ent cir­cum­stances in dif­fer­ent ar­eas of the river sys­tem. In the up­per river we can’t ma­nip­u­late cir­cum­stances with en­vi­ron­men­tal wa­ter, so that means work­ing with com­mu­ni­ties on other mea­sures. It’s all about get­ting the bal­ance right.”

• En­vi­ron­men­tal wa­ter re­leases in Macken­zie River and Burnt Creek are a pri­or­ity as part of the Vic­to­rian En­vi­ron­men­tal Wa­ter Holder’s Sea­sonal Wa­ter­ing Plan 2017-18, which aims to im­prove river and wet­land health across the state. Wim­mera CMA has re­leased its planned flows for sum­mer on­line at which it ad­justs depend­ing on weather con­di­tions.

DIS­COV­ERY: Arthur Ry­lah In­sti­tute fish ecol­o­gist Joanne Sharley and Scott Ray­mond dur­ing sur­veys of Macken­zie River and Burnt Creek.

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