Environmental Water Allocations in regulated lowland rivers may encourage offstream movements and spawning by common carp, Cyprinus carpio: implications for wetland rehabilitation

2012 ◽  
Vol 63 (10) ◽  
pp. 865 ◽  
Author(s):  
Anthony J. Conallin ◽  
Ben B. Smith ◽  
Leigh A. Thwaites ◽  
Keith F. Walker ◽  
Bronwyn M. Gillanders

Environmental Water Allocations (EWAs) are used to enhance native flora and fauna in regulated rivers, but may also benefit alien invasive species like common carp (Cyprinus carpio). We examined the invasion and spawning risk posed by adult common carp during an EWA delivered from the River Murray to a flow-through wetland in South Australia from June to December 2008. Offstream movements of fish and turtles were monitored continuously via the inlet and outlet creeks. Long-necked turtles (Chelodina longicollis, n = 129) dominated at the inlet where few fish were collected (n = 24), whereas much larger numbers of common carp in prime spawning condition (n = 4709), alien goldfish (Carassius auratus, n = 1201) and native bony herring (Nematalosa erebi, n = 93) were attracted to the outlet and displayed distinct movements. Adult common carp movements began in August, in response to increasing water temperatures, peaked in mid-September before spawning, then declined and were close to zero by December. The timing of EWA deliveries potentially could be manipulated to reduce adult carp invasion and spawning potential while providing some advantage to native fish, but the benefits may be short-lived without additional carp management interventions such as wetland drying.

2011 ◽  
Vol 62 (11) ◽  
pp. 1270 ◽  
Author(s):  
Henning Winker ◽  
Olaf L. F. Weyl ◽  
Anthony J. Booth ◽  
Bruce R. Ellender

As one of the most widely established freshwater fishes globally, the invasive success of common carp, Cyprinus carpio, is beyond dispute. Although detailed knowledge on its biology would assist in its management, relatively few life history studies have investigated C. carpio outside of its natural range. The present study analyses the life history and population structure of exotic C. carpio in a 364 km2 African impoundment. We used whole astericus otoliths to show that C. carpio attained ages of up to 7 years and grew more rapidly than has been recorded for any population from Europe or Australia. Macroscopic staging of gonads indicated protracted spawning, with highest reproductive activity observed during late spring and early summer. Total mortality, natural mortality and fishing mortality rates were estimated at 0.72, 0.60 and 0.12 year–1 respectively. Life history comparisons across the species’ global distribution showed large variations in growth and longevity, whereas early maturation (2–3 years) appeared to be a rather conservative trait. The combination of early maturity, fast growth and relatively high natural mortality rates suggests a rapid population growth potential associated with high resilience to management interventions once C. carpio has been introduced.


2006 ◽  
Vol 57 (3) ◽  
pp. 333 ◽  
Author(s):  
Ivor G. Stuart ◽  
Matthew Jones

Non-native common carp (Cyprinus carpio L.) are the most abundant large-bodied fish in the Murray–Darling Basin. The abundance of common carp larvae and young-of-the-year appears to increase after flooding, although the relative contribution of floodplain habitats compared to riverine areas remains unresolved. Larval nets were used monthly from September 2000 to January 2001 to identify common carp spawning and recruitment areas in the regulated Murray River and floodplain around the Barmah–Millewa forest. Five non-native and five native fish species comprising 136 111 individuals were collected, with common carp constituting 88% of the overall catch. Less than 1% of common carp, however, originated from the Murray River upstream of the Barmah–Millewa floodplain. Consequently, this floodplain appears to be a major source of common carp recruitment in the mid-Murray area. Conversely, eggs from large-bodied native fish were only present in the Murray River and not the Barmah floodplain. There are opportunities for common carp control in this area, to potentially reduce populations in a wider river reach. Implementation of common carp control measures in the Barmah–Millewa floodplain should be further investigated, particularly with regard to seasonal irrigation flows, obligatory migration routes and in the timing of future large-scale environmental water allocations.


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