Reports of fish with milky white flesh
In 2022, the Ministry for Primary Industries (MPI) received reports of some snapper and trevally being caught that had flesh that looked "milky white" or "mushy". This is being referred to as "milky white flesh syndrome". While the syndrome was more common over the 2022-23 season, it had been seen and reported in previous years.
The syndrome has been affecting snapper in the Hauraki Gulf and East Northland areas.
Initial tests found no biosecurity or food safety concerns
Testing of snapper with this syndrome has found no reason for any biosecurity or food safety concerns. The main finding from the affected fish was evidence of nutritional deficiencies. This can happen after fish spawn.
A summary of the testing report was published in the June 2023 edition of Biosecurity New Zealand's quarterly magazine, Surveillance.
Surveillance (June 2023) [PDF, 13 MB]
Research into the syndrome has highlighted multiple factors at play
An in-depth scientific report has found a mix of complex climate factors affecting food sources are likely causing milky white flesh syndrome.
Multiple factors highlighted in milky fish research
The National Institute of Water and Atmospheric Research (NIWA) undertook research on behalf of Fisheries New Zealand and collected a range of data, including information from commercial and recreational fishers about affected snapper and where it had been caught.
The syndrome has been most prevalent throughout the inner Hauraki Gulf, near Auckland, and around Doubtless Bay near Northland.
Snapper with the condition appear skinny and have mushy, white flesh instead of their usual translucent, firm flesh, and are malnourished.
A lack of food is likely to be causing the syndrome. The report highlighted a range of factors that could be causing this including extended La Niña weather patterns and warmer waters causing lower production of the phytoplankton and zooplankton that provide important food sources at the bottom of the food chain.
FAR 2024/25 Distribution and potential causes of milky fleshed snapper in SNA 1 [PDF, 5.1 MB]
Help us to continue monitoring the spread of milky white flesh syndrome
As a precaution, Biosecurity New Zealand is interested in reports of:
- affected snapper from outside the east of Auckland and Northland areas
- in finfish other than snapper.
If you find any suspected cases, freephone our pest and disease hotline on 0800 80 99 66.
If you have any fish to submit, keep them chilled (refrigerated) but not frozen, and send in the whole fish (not just the fillets). Samples are best when they can be analysed within 24 hours.
Pictures of fish affected by milky white flesh syndrome
Who to contact
If you have questions about the syndrome, email info@mpi.govt.nz
