Oral Presentation International Conference on River Connectivity (Fish Passage 2018)

Control of globally invasive common carp: a 10 year commercial trial of the Williams' carp separation cage in a Murray River fishway. (#163)

Anthony J Conallin 1 , Ivor G Stuart 2
  1. Local Land Services (Murray), Wodonga, VIC, Australia
  2. Kingfisher Research, North Eltham, Victoria, Australia

Common carp Cyprinus carpio, are a highly migratory pest fish in Australia, North America, New Zealand and parts of Europe. Fishways built to facilitate native fish passage also benefit invasive carp. The Williams’ cage was developed to separate carp from native fish as they pass through fishways by exploiting their unique jumping behaviour. We report on a 10-year commercial application in a fishway on the lower Murray River (SE Australia) where a high biomass of carp resides. 

Between November 2007 and April 2017, the automated Williams’ cage was installed and operated at Lock 1 by a collaborative team of river managers, weir keepers, commercial fishers and researchers. To date, over 700 tonnes of adult carp, (approx. 350,000 fish) have been removed at a maximum rate of 5 tonnes per day. The income generated from the sale of the fish has far exceeded set up costs. Catches and separation efficiencies were highest in spring (Austral) when fish were migrating to spawn. During the cage design phase, refinements helped reduce bycatch of non-target native fish to practically zero (0.03%) and informed future designs, application and operation.

The Williams’ cage has now successfully moved from an experimental idea to full commercial viability and could play a key role in controlling the dispersal and abundance of carp where high abundances preside and collaborative management alliances can be formed.