Thursday, January 24, 2008

January 08 floods lead to major Richmond River fish kill

Photo: Some of the huge number of fish that died following recent major flooding on the Richmond River.

My thanks to Tom from live from the northside for a post drawing my attention to a major fish kill on the Richmond River. I had heard mention on the radio, but Tom's post reminded me that I should say something.

This was not the first such event, nor have they been limited to the Richmond.

The NSW Department of Primary Industry records that a major fish kill occurred in early February 2001 following major flooding in the upper reaches of the Richmond River catchment. Fish kills were also recorded at this time in tributaries of the Tweed and Brunswick Rivers. Subsequent flooding in March 2001 resulted in a major fish kill in the Macleay River and minor fish kills in the Clarence River.

The Department states that the cause of the fish kills was extremely low dissolved oxygen levels in the rivers. This most likely resulted from the death of pasture grasses inundated by floods which removes oxygen from the water and the rapid drainage of this floodplain water into the river. Also, sediments from acid sulphate soil floodplains were also a likely contributor of low dissolved oxygen in the water. Key sources of this low oxygen to the system were all areas that were formerly important fish habitats, wetlands that had been extensively drained and floodgated.

As a response to the major fish kills, NSW Fisheries closed the Richmond River and near shore areas to all forms of fishing, for three weeks initially and then extended this closure a further three months. A closure to all forms of fishing was placed on the Macleay River for 3 months on 20 March 2001.

The fish kill and river closures had adverse effects on local communities, especially at Ballina and South-West Rocks. These impacts, particularly lost revenue from cancelled visits by tourists, affected bait and tackle stores in particular and other businesses such as motels, caravan parks, service stations, seafood outlets, Fishermen's Co-operatives, boat-hire and maintenance businesses. Despite the economic impact on the community, the river closures received widespread industry and community support.

The closures to fishing in the rivers were modified following consultation with the Recovery Committees, analysis of scientific data and community input that occurred after a general call for submissions. The total closures were replaced with less restrictive recreational and commercial fishing closures on the Richmond and Macleay Rivers. These included daylight fishing hours only, restricted total bag limits and limits on the available fishing area. These new restrictions lasted for a period of 3 months in both rivers.

The partial river closures were lifted on 28 September 2001, following positive results from the scientific surveys, allowing for the resumption of normal commercial and recreational fishing.

Those who are interested can find the full report on the earlier incident by following the link.

This time the floods do not appear to have affected the other rivers, but the effect on the Richmond has been very severe, with an estimated 33 tonnes removed by Council from the worst affected area near Ballina. Fishing has again been banned from the river for a period of three months.

Last year there was a story on the ABC about the work of an individual farmer who had been experimenting with new types of farming practices to try to overcome the problem. For the life of me, I cannot remember the details. I will try to find the story, for it was quite inspiring.

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