Severe weather patterns off the West Coast of Tasmania last week resulted in a loss of around 55,000 (16 Year Class) fish in Petuna’s Table Head lease in Macquarie Harbour.
The inversion event was very similar to that experienced by Petuna in 2015, but due to the company’s learnings from that event, the stock loss was significantly lower this time around.
The low pressure combined with strong westerly winds created an influx of seawater into the Harbour, pushing the deeper lower oxygenated water to the surface.
The impact of the storm hit Petuna’s Table Head lease, being situated closest to Macquarie Heads, but the company’s three other leases in the harbour were unaffected.
Petuna said the affected fish pens had been cleared of the mortalities and would have no material impact on ongoing supply.
The majority of mortalities were transported to Dulverton to be processed into compost, while approximately 20,000 fish were buried in landfill on the West Coast, pre-approved by the Environment Protection Authority.
Under normal circumstances all the fish would be taken to Dulverton. However, due to the current fruit fly crisis, there was a shortage of appropriate transport equipment.
Petuna said the priority was to remove the fish from the Harbour swiftly and this was achieved with the company also receiving assistance from both Tassal and Huon Aquaculture.
Following the event, environmental conditions and feeding behaviour have now returned to normal.