The first investigation of the salmon deaths in 2012
The higher than usual deaths occurred on the Waihinau Bay farm. The Ministry for Primary Industries (MPI) worked closely with the company involved to investigate and manage the situation. MPI looked at a number of factors that could be involved in the fish deaths, including the environment, management at the farm, and the presence of bacteria.
Testing at the time found no particular pathogens involved and the conclusion was that environmental factors were likely to have caused the deaths.
The 2012 salmon investigation report [PDF, 155 KB]
Further investigation and response
By 2015, increased mortalities were occurring at a number of Marlborough farms and MPI’s Animal Health Laboratory had developed new diagnostic tests for fish pathogens. These new tests revealed the presence of 2 bacteria – the New Zealand Rickettsia-like organism (NZRLO) and Tenacibaculum maritimum (TM).
MPI believed the bacteria, which occur naturally in the Marlborough region, could have contributed to the fish deaths, in combination with a range of other factors. A second investigation report was published in May 2017.
The 2017 salmon investigation report [PDF, 687 KB]
MPI then set out to determine whether NZRLO and TM were the primary cause of the deaths, and to prevent the spread of the diseases to other salmon farming areas and wild salmon.
Our response included putting in place a Controlled Area Notice, restricting the movements of live fish stock and aquaculture equipment from affected farms.
Risk assessment in 2023 and closure of biosecurity response
An independent, science-based risk assessment was completed in September 2023 and concluded that:
- NZRLO and TM played only a minor role in the deaths
- the mortalities were mainly due to a number of other causes, including environmental factors (for example, warmer water) and farming practices.
With the receipt of this assessment, Biosecurity New Zealand is satisfied that these bacteria do not pose an ongoing biosecurity risk to New Zealand. Consequently, the legal controls (the Controlled Area Notice) restricting stock and equipment movements are no longer required. We have closed the biosecurity response. Future management will be undertaken by the company with support from Biosecurity New Zealand.
Risk assessment report [PDF, 1005 KB]
