Study shows rivers stable

Research suggested fish communities in the Swan and Canning rivers, from Mosman Park and upstream to the Swan Valley and Kent Street Weir, had improved since the mid-2000s.

The index measures estuary health by calculating the diversity and number of fish species in the rivers.

Water quality, seagrass growth and distribution, and a survey of foreshore conditions are also calculated.

Environment Minister Albert Jacob said the index was consistent with the pattern of good-fair condition assessments in previous years.

�In total, 35 species and more than 30,825 fish were caught and released in shallow waters and 21 species and 1601 fish were caught and returned in deeper waters by scientists,� he said.

�It is important to note that the number of species caught in deeper water was consistent with those in 2012 and 2013.

�However, the number of species recorded in shallower waters in 2014 was notably higher than the 29 species recorded in the previous two years.�

Mr Jacob said the rivers were under pressure from climate change, historical land use and development, but the fish community results showed the rivers were stable.

�This year�s results reflect high and stable salinity in the rivers, higher oxygen levels and the absence of algal blooms across much of the waterway,� he said.

�It�s true that some parts of the river system are healthier than others but the claim that the river is dead is just not supported by the science and monitoring.�