ES changes shellfish site monitoring

Testing recently showed the Jacobs River Estuary in Riverton was one of the shellfish-gathering sites in Southland which had in the past been identified as not being safe for food gathering.

THE way Southland shellfish monitoring sites are tested has changed.

A decision was recently made to reallocate resources to improving water quality, rather than following up on known issues monthly.

Environment Southland (ES) science manager Elaine Moriarty said shellfish sites would now be assessed after three years’ improvement work.

“As opposed to going out every month and saying, ‘yep, it is still red’.’’

Results had been consistent, she said.

This time last year, a report was released from 2016-17 which states shellfish from only one of eight gathering sites in Southland was safe for human consumption. ES used to post results of shellfish sites to its website, but since the approach changed it listed only swimming sites.

The testing change did not affect the weekly summer monitoring of recreational water quality sites, several of which overlapped with shellfish sites.

The first results of summer should be ready at the beginning of December.

Dr Moriarty said the method for testing had been developed about 30 years ago, and it had been recognised for not providing a good overall picture.

“We don’t have a lot of confidence in the validity of the method.”

She was unable to give a figure on the cost of resources for monthly testing.

Her advice was for people to be aware of the environment they were in.

An example was to not swim or collect shellfish after heavy rain, or when people could not see their toes in knee-deep water.

Water quality was affected mainly by farm runoff, discharge and birds. Research shows avian pollutants are a big factor in water degradation in Southland.

Throughout New Zealand, work was under way to introduce predictive modelling.

“You can imagine we would say, ‘right, based on the weather forecast, what we know in the area, what discharges we know,’ we would create a computer model that would be able to give a predictive value.”

Dr Moriarty suggested cooking shellfish and following food preparation guidelines to minimise health risk.

  • For information on swimming sites go to or through ES.

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