A survey of marine life in the East Otago Taiapure has revealed a decline in the number of paua, a scientist says.
Te Runanga o Ngai Tahu senior environmental adviser Derek Richards, of Dunedin, said he was in a team of ecologists monitoring 28 permanent sites in the taiapure, which spans from Purakaunui to Waikouaiti.
The monitoring work was for Ngai Tahu, in conjunction with the University of Otago.
The 28 sites include a site at Warrington and 14 sites on Huriawa Peninsula at Karitane.
Ecologists surveyed paua in up to five depths of the 30m-long sites.
“This is probably the most studied and surveyed paua fishery in New Zealand.”
The research provides an estimate on the density and size of paua – both ordinary and yellowfoot species.
Surveys in the 14 sites in 2008, 2012 and 2016 had revealed a decline in the paua population.
In 2008, on average, 14.1% of paua in the taiapure were of legal size, he said. In 2016, only 4.8% were legal.
The data excludes the 14 sites at Huriawa Peninsula, which was closed to paua fishers in 2010 because of declining stock.
The reason for the decline in paua stock includes poaching and environmental impacts including an increase in sand, reducing the amount of rock habitat available to the shellfish.
Other environmental factors could be warmer sea temperatures and ocean acidification, he said.
The legal size for paua is 125mm for ordinary and 80mm for yellowfoot.
In the fishery, a paua took up to 10 years to grow to a legal size, he said.