The Environmental Protection Authority on Wednesday made the final determination on biomass levels in the harbour, based on recent research findings by the Institute of Marine and Antarctic Studies and other information. 

Director Wes Ford said he considered the very low levels of dissolved oxygen in the deeper waters of Macquarie Harbour, the extent of the presence of Beggiatoa species, and a decline in benthic fauna in the vicinity of the marine farms.

The cap for fish in the harbour is 21,000 tonnes per hectare.