Changes in the fish fauna of the Swan-Canning Estuary since the 1970s - How, why and what does it mean?
Valesini, F., Hallett, C. and Hoeksema, S. (2011) Changes in the fish fauna of the Swan-Canning Estuary since the 1970s - How, why and what does it mean? In: Swan River Trust Forum, 2 November, Perth, Western Australia.
The fish fauna of the Swan-Canning Estuary has been studied during several annual periods between the late 1970s and late 2000s by various researchers at the Centre for Fish and Fisheries Research, Murdoch University, i.e. 1976-1981, 1993/94, 1995-1997, 1999-2001, 2003/04, 2005-2007, 2008-2009. Although the sampling regimes have differed among some of those studies (which have been compensated for, as far as possible, using a variety of methods), this historical data set provides a rare and valuable opportunity to examine whether the fish fauna has changed over the last three decades, and to identify whether any such changes are related to those in the water quality of the system. Comprehensive analyses of these data have shown that the fish faunal composition in the shallow waters has changed markedly between the late 1970s and 2009. Differences between annual periods had a far greater impact on fish composition than did changes between seasons and/or zones of the estuary. In several zones, these changes were often driven by decreased catches of Perth Herring (Nematalosa vlaminghi), Sea Mullet (Mugil cephalus) and Yellow-eye Mullet (Aldrichetta forsteri) since the 1970s, and by increased catches of the Southern Black Bream (Acanthopagrus butcheri). The fish fauna in deeper waters has also changed significantly from earlier to later periods, again due mainly to lower catches of N. vlaminghi and/or M. cephalus, but also to lower catches of A. butcheri. Potential causes of these observed changes in fish fauna, including the influences of water quality, are investigated.
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|Murdoch Affiliation:||Centre for Fish and Fisheries Research|
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