Pouched lamprey (top) and short-headed lamprey (below). Photo: Tracey Steggles
Water for the environment has helped drive a spectacular increase in lamprey numbers in the Murray-Darling Basin.
Lamprey - an ancient, eel-like fish - can migrate up to 2000 kilometres between the ocean and the River Murray to breed. The ocean and the Murray must stay connected for lamprey to enter the freshwater system and complete their lifecycle.
With large volumes of water extracted from the river to support towns, farming and industry, in dry times lamprey rely on water for the environment to keep the river system healthy and flowing into the Coorong.
During the Millennium Drought from 2001 to 2009, many native fish suffered from the lack of freshwater inflow from the Murray to the Coorong. Between 2007 and 2011 there were no pouched lamprey detected and only one short-headed lamprey detected from 2007-2018. This suggests that lamprey numbers declined as they were unable to migrate upstream to breed.
So far this year, a record 101 pouched and three short-headed lamprey have been found swimming through the Lower Murray barrages. The previous record was 61 in winter 2019.
Pouched lamprey oral disk. Photo: Adrienne Rumbelow
“We’re thrilled to be recording more lamprey moving into the Murray this winter than ever before. We’re seeing the results of water managers from across government agencies working together to get conditions just right to support native fish like lamprey,” said South Australian Minister for Environment and Water, David Speirs.
Commonwealth Environmental Water Holder, Jody Swirepik said, “with water for the environment in the system, we have been able to keep the Murray connected with the Coorong for ten years. This has driven a gradual and significant increase in the number of lamprey and other native fish.”
Principal Research Scientist with CSIRO, Brenton Zampatti said, “our ability to fine-tune barrage releases for native fish such as lamprey has been supported by 15 years of research and data collection at the barrages. We are able to target flows to facilitate migration and recruitment for different species of native fish at various times of the year, meaning we can be efficient with the use of water for the environment.”
The lampreys are being tracked by scientists at the South Australian Research and Development Institute (SARDI) as they move through fishways along the River Murray.
“We know the lamprey can swim hundreds of kilometres up the river, but the exact location of their spawning grounds in the Murray-Darling Basin is still a mystery. By tagging lampreys with microchips we are learning more about their movement and hope to one day solve the mystery of where they spawn. This knowledge will help inform how the river is managed so that we can better support the recovery of the species,” said SARDI Research Scientist, Chris Bice.
Lamprey monitoring is funded by The Living Murray program, a joint initiative with the New South Wales, Victorian, South Australian, and Commonwealth governments coordinated by the Murray‑Darling Basin Authority. Monitoring at the Lower Murray barrages is also supported by SA Water and CSIRO.
Left: A large catch of pouched lamprey from this year. Photo: Chris Bice, SARDI. Right: The Tauwitchere vertical-slot trap being deployed. Photo: Chris Bice, SARDI