Re­searchers come to grips with a fishy prob­lem

Western Suburbs Weekly - - Near You -

AC­TU­ALLY hold­ing the an­cient and en­dan­gered western trout min­now was dif­fi­cult dur­ing the species’ first ar­ti­fi­cial breed­ing by UWA fish re­searchers ear­lier this year.

“Work­ing as a fish bi­ol­o­gist, this work was at the mi­cro scale as usu­ally we deal with breed stock trout at 5kg6kg, but th­ese trout min­nows were 5g6g,” Depart­ment of Fish­eries prin­ci­pal re­search sci­en­tist Craig Lawrence said.

Dr Lawrence and his Shen­ton Park team used IVF tech­niques on the tiny trout min­now, which rarely grow to 20cm.

In 2006, 2000 to 5000 of the wild fish were es­ti­mated to live in three Great South­ern rivers.

“They are very dis­tantly re­lated to the north­ern hemi­sphere’s trouts, but they are a Gond­wana su­per-con­ti­nen­tera relic,” Dr Lawrence said.

Other min­nows and its rel­a­tives are in New Zealand and South Amer­ica, both of which have species from the su­per-con­ti­nent after it split from other an­cient land­masses about 180 mil­lion years ago.

The trout min­now is WA’s only criti- cally en­dan­gered fish but its true plight was only dis­cov­ered when no na­tive fish were found in wa­ter­ways near Perth in 2010.

Like north­ern hemi­sphere brown and rainbow trouts, the min­now swims up­stream to find gravel beds – known as redds – to lay eggs, so dams that block breed­ing and a 20 per cent drop in South West rain­fall in 30 years are thought to threaten the na­tive fish.

Dr Lawrence said he ini­tially con­sid- ered the trout min­now a rem­nant pop­u­la­tion, iso­lated by time and ge­og­ra­phy, and global warm­ing would in­evitably cause its ex­tinc­tion in 50 years.

How­ever, the fish, ma­tur­ing at two years, sur­vives in wa­ter up to 28C and un­der­stand­ing that abil­ity could have im­pli­ca­tions for aqua­cul­ture species fac­ing global warm­ing.

Sav­ing the trout min­now us­ing hatch­ery re­search started five years ago after the univer­sity’s team the­o­rised spawn­ing needed cor­rect wa­ter tem­per­a­tures, wa­ter flows and right air pres­sure.

They col­lected ma­ture wild fish, their eggs and sperm and used IVF tech­niques for fer­til­i­sa­tion be­fore about 2000 fin­ger­lings spawned at the Shen­ton Park hatch­ery dur­ing nights through­out April.

“Th­ese pre­cious fish will now be used to de­velop a cap­tive breed­ing pro­gram to save the species from ex­tinc­tion, by es­tab­lish­ing an ‘ ark’, or repos­i­tory pop­u­la­tion at the UWA lab­o­ra­tory, and in the longer term re­stock­ing wa­ter bod­ies,” Dr Lawrence said.

Kent An­der­son is UWA’s new Deputy Vice-Chan­cel­lor for Com­mu­nity and En­gage­ment.

Pic­ture: An­drew Ritchie­mu­ni­ d425004

Dr Craig Lawrence has bred tiny and en­dan­gered trout min­nows for the first time at UWA.

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