Still trying to find the reason. Maybe this, from EDO TAS Does...

Still trying to find the reason.
Maybe this, from EDO TAS
Does not sound it would cause the drop but i can not find anything else.

"
The Finfish Farming Environmental Regulation Act 2017 came into effect on 4 December 2017, making changes to the Marine Farming Planning Act 1995, Living Marine Resources Management Act 1995 and the Environmental Management and Pollution Control Act 1994. Key changes include:

• Formally transferring environmental regulation functions over finfish farms to the EPA Director
• Introducing a new Environmental Licence for finfish farming operations, and making such activities “Level 2 activities” to be assessed by the EPA.
  • For inland finfish farm facilities and related activities, applications must be assessed by the EPA Board (and subject to public consultation and appeal rights)
  • For marine based finfish farming, the EPA Director will determine whether referral to the EPA Board is required
• Introducing marine farm exclusion zones and declaring an initial zone over Mercury Passage (excluding the existing Okehampton Bay lease)"