A combination of many causes for deformed scallops

A combination of many causes for deformed scallops

Tests undertaken by MPI’s Animal Health Laboratory show a combination of many factors is behind the recent poor condition of the scallop populations around Great Barrier and Mercury Islands and in Pelorus Sound.

Earlier this year callers to the Ministry for Primary Industries (MPI) 24-hour Exotic Pest and Disease Hotline (0800 80 99 66) reported deformed, watery and smaller than normal scallops in three locations.

MPI Animal Health Laboratory (AHL) tested scallops collected from all three areas to determine if the decline in the beds and/or deformation of the roe and muscle was caused by an exotic disease or organism. AHL staff applied general aquatic bacteriology testing, histopathology and molecular testing to the scallop specimens and concluded the mortality and poor condition of the scallop populations are likely the result of a combination of causes.

The specimens from Pelorus Sound showed a high load of an opportunistic bacterium common in New Zealand waters. Samples from all three sites were affected by a protozoan parasite that infects molluscs and is found in other shellfish species around the North Island and the top of the South Island. There was also inflammation and some degeneration of the digestive tract in some of the scallops. This digestive tract damage is found in samples from all three sites and is the most significant finding in the investigation.

The affected scallops do not pose a food safety risk. However, as is the case with any animal, shellfish that are obviously sick and dying should not be eaten.

MPI Manager Surveillance & Incursion Investigation, Brendan Gould says MPI will continue to keep a close eye on the wellbeing of these scallop fisheries and encourages fishers and members of the public to report any concerns or abnormalities they observe.

“MPI takes the health of the scallop fisheries very seriously. We also act on information received via the Exotic Pest and Disease Hotline so I’d urge people who gather shellfish to phone 0800 80 99 66 if they notice anything unusual.”

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