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Malnutrition may be the cause of the number of mushy fleshed fish in the Hauraki Gulf, although experts say it is too early to say definitively.
LegaSea representative Sydney Curtis told the Hauraki Gulf Forum on March 4 that there was a high proportion of fish affected by mushy flesh – snapper, kahawai, trevally, king fish, gurnard and, more recently, blue cod.
“The skeletal muscle is reabsorbed and that is attributed to prolonged malnutrition,” Curtis said.
A survey last year revealed that mushy fleshed fish were being reported predominantly in the Hauraki Gulf. The cause of malnutrition was unclear and accompanied by outbreaks of parasites.
“Fish are more susceptible [to parasites] if there is already something wrong in the ecosystem,” he said.
Ministry for Primary Industries representative and forum member Jacob Hore said initial testing ruled out any parasitic or bacterial related causes.
“The big question is what is causing the malnutrition,” he said. “A live research project has been set up to look at this.”
Forum member Warren Maher said the mushy fleshed fish issue was possibly worse than caulerpa.
“We have seen a dramatic decrease in our bait fish populations due to overharvest. It’s obvious that they are starving,” Maher said.
Curtis said there were a lot of unknowns about bait fish.
“We don’t have a stock status for jack mackerel or pilchards. We know scallops and muscles are virtually non-existent unless they are in an aquaculture. We can’t assume that just because snapper will eat everything that they are going to move on to something else.”
