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

Evaluation of a fish friendly  pump for increasing the survival of downstream migrating shortfin eels (Anguilla australis) in the Waikato, New Zealand   (#176)

Jacques A.T Boubée 1 , Mike Lake 2 , Amy Y Yasutake-Watson 2 , Bruno O David 2
  1. Vaipuhi Freshwater Consulting LTD, Hamilton, Waikato, New Zealand
  2. Waikato Regional Council, Hamilton , Waikato, New Zealand

Large areas of high-value agricultural land in New Zealand are serviced by flood and drainage pumps. While critical to maintaining the viability of this farmland, these pumps are also known to be a migration barrier to fish, and cause mortality and injury to fish entrained by them.  The risk to New Zealand’s native freshwater eels is particularly high due to their long body shape and catadromous life-history.  In 2017 the first purpose-built “fish friendly pumps” used in New Zealand were imported from the United Kingdom and installed at the Orchard Road Pump Station in the Waikato Region.  While these type of pumps had been tested on European eels it was unclear how safe they would be for New Zealand species which tend to grow to a larger size.  A monitoring programme was implemented to test the efficacy of the new pumps so that their role in future pump station remediation could be evaluated.The movement of downstream migrant eels passing through the new pump station was carried out using Passive Integrated Transponders technology and the attachment of large sock nets over the pump outlets. To increase sample size 98 adult migrant-phase eels were translocated above the pump station.  The condition of eels that had passed through the pump was made using visual assessments, post-mortem examinations and x-ray imagery.The results have shown a significant increase in the survival of downstream migrants compared with the pre-existing pumps at the site. However, a high rate of sub-lethal injuries were detected, and it is unknown how these injuries may affect the ability of migrant eels to successfully complete their life cycles. The potential implications of these findings on future pump station remediation in New Zealand is discussed.