[ASC-media] Add potassium, grow fish

joanne.finlay at agric.nsw.gov.au joanne.finlay at agric.nsw.gov.au
Mon May 2 09:33:43 EST 2005

NSW DPI Media Release
2 May 2005

Trout harvested in inland aquaculture trial
Rainbow trout are being harvested in the Riverina, as part of a bold 
experiment to make inland saline areas productive again.

NSW DPI Principal Aquaculture Scientist, Dr Geoff Allan, said scientific 
trials are being run at the Inland Saline Aquaculture Research Centre at 
Wakool, in western NSW, to determine the viability of growing marine and 
freshwater fish in inland areas. 

Dr Allan said the research indicates that not only trout, but a variety of 
marine fish - including snapper, mulloway, black tiger prawns and kuruma 
prawns  - are capable of surviving in degraded inland environments.

"The main difficulty appears to be that salt-affected groundwater contains 
far too little potassium - about 95 percent less potassium than salt water 
from oceans, despite having the same salinity", he said.

"When potassium in the form of potash is added to levels 40% or higher 
than those  in seawater of the same salinity, marine species such as 
prawns and mulloway not only survive ? they also grow at similar rates to 
what they do in seawater."

Dr Allan said two freshwater species have also been tested ? silver perch 
(Bidyanus bidyanus) and rainbow trout (Oncorhynchus mykiss).

"Silver perch can survive in groundwater that contains one-third the salt 
of seawater; while rainbow trout are able to survive in saline water which 
is as salty as seawater. 

"Potassium does not need to be added for either of these freshwater 

Small-scale production of rainbow trout began at Wakool in April last 
year. The facility contains six 0.05 hectare earth ponds lined with 
plastic, which are supplied with freshwater and saline groundwater.

Dr Allan said the first run of trout from the ponds yielded about half a 
tonne., Some of these trout were smoked but most were sold fresh through 
butchers in Deniliquin, Barham, Wakool and Finley.  They were very popular 
with consumers in the area who often struggle to purchase fresh fish. 

Imports of seafood to Australia have risen by 52% in the decade to 2002 
and the value of aquaculture trebled in this period.

Dr Allan said expansion of coastal aquaculture is limited by a shortage of 
sites with the necessary water quality, depth and proximity to suitable 

Dr Stewart Fielder and Mr Grant Webster of NSW DPI are running the project 
with an industry partner, Murray Irrigation Limited. It is also supported 
by the Australian Centre for International Agricultural Research and the 
Fisheries Research and Development Corporation.

Further information: Dr Geoff Allan, Port Stephens 4916 3909, 0419 185510 
Media contact: Joanne Finlay
Science Communication Specialist
PH: 63913171
Mobile: 0428 491813
Fax: 6391 3199

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