Complex climate factors are likely causing Milky White Flesh Syndrome in snapper, according to a Fisheries New Zealand report.

The syndrome, affecting snapper in the Hauraki Gulf and Doubtless Bay, results in skinny fish with mushy, white flesh.

"Early and ongoing tests ruled out exotic disease and food safety issues, meaning that fish with the syndrome are still safe for people to eat if they choose to," said Simon Lawrence, Fisheries New Zealand’s director of science and information.

The report suggests extended La Niña weather patterns and warmer waters have lowered the production of phytoplankton and zooplankton, crucial food sources for snapper.

Warmer ocean temperatures may also be affecting snapper metabolism, increasing their energy requirements.

Lawrence stated that the prevalence of the syndrome appears to be declining, supporting these theories.

"Overall, we’ve been seeing more snapper in the Hauraki Gulf for some time. The fishery is abundant, with plenty of younger fish entering the stock, all competing for food."

The National Institute of Water and Atmospheric Research (NIWA) conducted research, gathering data from commercial and recreational fishers.

Findings indicated no correlation between bottom trawling areas and the syndrome's prevalence.

Fisheries New Zealand continues to investigate recent reports of snapper with similar symptoms on the North Island’s west coast, with no biosecurity concerns identified.