Probe into mass die-off of crayfish

An investigation has been launched after a mass die-off of ko¯ ura (native freshwater crayfish) was found in a South Otago stream on Thursday.

Riki Parata, of Gore’s Hokonui Ru¯ nanga, said the discovery of at least 70 ko¯ura and one kokopu (native fish) in a culvert in an unnamed tributary of the Waipahi River was ‘‘really concerning’’.

‘‘We don’t want to point the finger at anyone but we’re really just trying to highlight to people [that] the effects of what they do on land and in the rivers have an effect on our taonga,’’ Parata said.

The ru¯ nanga had contacted the Otago Regional Council, which was investigating.

Some of the ko¯ura and the kokopu were still alive when they were found and were taken back to the ru¯ nanga, which has a tank to house the species. Despite best efforts, they died overnight.

Parata did not know what had caused the deaths, but he knew of two mass deaths of ko¯ura in the North Island that had been caused by forestry sprays.

‘‘Ko¯ ura are very susceptible to herbicides and pesticides, or it could have been an effluent discharge which removes all of the oxygen from the water.’’

They had taken water samples at the site and had frozen the bodies so toxicology investigations could be carried out.

The die-off was found while ru¯ nanga members were conducting surveys of ka¯kahi (freshwater mussels) with a University of Canterbury PhD student.

An Otago Regional Council spokesperson said council staff were investigating.