Editing Murray cod (section)

====Effects of river regulation====
The Murray River and southern tributaries originally displayed a pattern of high flows in winter, high flows and floods in spring, and low flows in summer and autumn. The breeding of Murray cod and other Murray-Darling native fish was adapted to these natural flow patterns. River regulation for irrigation has reversed these natural flow patterns, with negative effects on the breeding and recruitment of Murray cod. The Murray and most southern tributaries now experience high [[irrigation]] flows in summer and autumn and low flows in winter and spring. Small and medium floods including the once annual spring flood-pulse have been completely eliminated.<ref name=Allen-et-al2002/><ref name=McDowall1996/><ref name=Koehn2004>
{{Cite web |last=Koehn |first=J. D. |title=Threats to Murray cod |publisher=Murray Darling Basin Commission |date=2004 |url=http://www.mdbc.gov.au/__data/page/641/4_John_D._Koehn.pdf |access-date=4 October 2007 |url-status=dead |archive-url=https://web.archive.org/web/20070829102517/http://mdbc.gov.au/__data/page/641/4_John_D._Koehn.pdf |archive-date=29 August 2007}}</ref><ref name=sharing>{{cite book  | title = Sharing the Murray
  | publisher = Murray River Entitlements Committee  | year = 1997  | isbn = 0-7306-6797-9}}</ref>

It is estimated that flows at the river mouth by 1995 had declined to only 27% of natural outflows.<ref name=mdbcaudit1995>{{cite book |url=http://www.mdbc.gov.au/__data/page/101/WAM-Report-2004-05.pdf |title=Water Audit Monitoring Report 2004/05 |author=Murray-Darling Basin Commission| author-link=Murray-Darling Basin Commission|date=June 2006|isbn=1-921-038-93-4 |access-date=2007-09-28 |url-status=dead |archive-url=https://web.archive.org/web/20060906154918/http://www.mdbc.gov.au/__data/page/101/WAM-Report-2004-05.pdf |archive-date=2006-09-06 }}, retrieved 28 September 2007</ref> The probability of the bottom end of the Murray experiencing drought-like flows had increased from 5% under natural conditions to 60% by 1995.<ref name=mdbcaudit1995/>

[[Thermal pollution]] is the artificial reduction in water temperatures, especially in summer and autumn, caused when frigid water is released from the bottom of reservoirs for irrigation demands. Such temperature suppression typically extends several hundred kilometres downstream. Thermal pollution inhibits both the breeding of Murray cod and the survival of Murray cod larvae, and in extreme cases inhibits even the survival of adult Murray cod.<ref name=nfacod/>

The rare floods that do break free of the dams and weirs of the Murray-Darling system have their magnitude and duration deliberately curtailed by river regulators. Increasing research indicates this management practice is very harmful and drastically reduces the general [[ecosystem]] benefits and breeding and recruitment opportunities for Murray cod and other Murray-Darling native fish species these now rare floods can provide.<ref name=Allen-et-al2002/><ref name=McDowall1996/><ref name=Koehn2004/><ref name=sharing/>