Deaths of nearly 270 eels investigated
The cause of death of hundreds of eels in a Southland waterway is being investigated, and an ammonia leak at a meat processing plant or the Southland drought could be possible causes.
Environment Southland acting compliance manager Donna Ferguson said 263 dead eels were found along a stretch of water in Bateman’s Creek in the West Plains area on March 27.
The council’s incident response team canvassed the area extensively and located the eels in or near the single waterway.
The eels were respectfully disposed of in consultation with iwi, she said. ‘‘Samples of the water were tested for dissolved oxygen and a number of contaminants. Oxygen levels in the water were low, which could be caused by a number of factors including the low water levels and increased water temperature at the time,’’ Ferguson said.
The tests for contaminants did also not provide any answers as to the cause of death. ‘‘A number of eels were sent away for testing, but we don’t have these results back yet.
‘‘Identifying specific causes in these situations can be difficult as any contaminants will move quickly through a waterway and often be undetectable by the time we are aware of the situation,’’ she said.
The regional council warned people not to have contact with the water or to take watercress from it on a social media post on March 28.
A drought was declared in Southland on March 31, when the regional council said rainfall on the south coast was the lowest since records began 50 years ago and some rivers were at levels only seen about every 80 years.
A week earlier, on March 22, there was an ammonia link at Alliance Group’s Lorneville plant, which is also located at West Plains.
Fire and Emergency NZ sent an alert to cell phones advising residents in the area to keep their windows and doors closed because of the leak.
Alliance Group general manager manufacturing Willie Wiese said the company was working closely with Environment Southland to ascertain the cause of the situation, including examining whether warm weather and low water flows were to blame.
‘‘Following the ammonia leak at the Lorneville plant on March 22, we put contingency measures in place to control the discharge of stormwater from the plant, diverting the stormwater discharge to our wastewater treatment ponds. The eels were discovered approximately four to five days after the ammonia incident.’’
He noted Alliance Group invested in native eel conservation programmes including at Mataura where it supported Hokonui Rū nanga to help native New Zealand baby eels (elvers) – or tuna – to migrate up the Mataura River.
‘‘Identifying specific causes in these situations can be difficult as any contaminants will move quickly through a waterway . . .’’ Donna Ferguson Environment Southland acting compliance manager