In early March Tasmania’s Inland Fisheries Service received a report of dead fish in the Derwent River between upstream New Norfolk and the area downstream near the industrial mill Norska Skog. For further reading refer to http://www.ifs.tas.gov.au/news/river-derwent-fish-kill-restricted-to-barracouta. The thinking was that “The most likely cause is that barracouta have followed the salt wedge with the high tide in the river and killed by their sudden entrapment in freshwater.”
One of this week’s news stories reported on monitoring the unexpected numbers of fish dying in groups. The story can be read at http://www.abc.net.au/news/2015-03-27/more-monitors-on-river-derwent-as-fish-kills-continue/6354950. In an earlier article http://www.themercury.com.au/news/tasmania/experts-examine-mass-fish-kill-in-upper-derwent-estuary/story-fnj4f7k1-1227256722478, the thinking was that “Water quality in the lower saline layer is typically poor in summer.”
Quite separately another story was running and I can find no-one publically connecting the two: “Fish kills could occur if the large algal bloom in the River Derwent near the Murphys Flat wetlands grows.” For further information read http://themercury-au.newspaperdirect.com/epaper/viewer.aspx.
I expect to be walking past Murphy’s Flat in the next day or so and I hope not to smell dying fish or see the silvery scales of dead fish littering the River’s edges.