Tēnā koe
An in-depth scientific report has found a mix of complex climate
factors are likely causing Milky White Flesh Syndrome.
Fisheries New Zealand's director science & information, Simon
Lawrence, says snapper with the condition appear to be skinny and
have mushy, white flesh rather than their usual translucent, firm flesh,
and are malnourished.
"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," says Simon Lawrence.
"The evidence suggests a complex interplay between factors,
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.
"This is a complex issue, and is more likely to be due to the effect of
recent weather patterns and natural changes in fish biology
throughout the seasons. Prevalence of the syndrome appears to be
declining which supports these theories.
"Warmer ocean temperatures may also be affecting snapper
metabolism, meaning they need to use more energy and require more
food."
Mr Lawrence says the report found that a lack of food was the likely
cause of the syndrome, but there was no evidence to suggest that
fishing was the cause of that.
"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.
"Commercial fishing does not affect the main food sources of
snapper.
"They are opportunistic feeders and are unfussy about what they will
eat."
Mr Lawrence says the areas in the Gulf where bottom trawling was
permitted did not correlate with the areas where the syndrome was
most prevalent.
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.
Researchers considered data gathered from fishers together with
environmental information, such as sea surface temperature, to
determine if any changes had occurred in the period before fish with
the syndrome were seen.
"We know that individual growth rates of all snapper around New
Zealand have declined over the last 15 years as snapper abundance
has increased, which could be explained by the mix of factors at play."
Fisheries New Zealand has received recent reports about snapper with
a few similar symptoms on the North Island's west coast. Some initial
tests have been undertaken and Fisheries New Zealand continues to
investigate, but there are no biosecurity concerns.
"The report underlines this complexity and its insights will be used in
future fisheries assessments," Mr Lawrence said.
Distribution and potential causes of milky fleshed snapper in SNA 1 -
Report [PDF, 5.1 MB]
For further information and general enquiries, call MPI on 0800 00 83
For media enquiries, contact the media team on 029 894 0328.
Please pass this on to anyone who may be interested.
Nāku noa, nā
Recreational Fisheries
Fisheries Management | Fisheries New Zealand - Tini a Tangaroa
Charles Ferguson Tower | PO Box 2526 | Wellington | New Zealand
Web: fisheries.govt.nz
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