The Ministry of Fisheries is shocked by a dramatic drop in Marlborough Sounds blue cod.
National Institute of Water and Atmospheric Research (Niwa) survey results released today show a 57 percent average decline of juvenile blue cod within the inner Queen Charlotte Sounds since the last major survey in 2004.
Ministry of Fisheries chief scientist Pamela Mace said the decline in blue cod was substantial.
"While some fishers will no doubt be able to catch blue cod in the Sounds, overall numbers are low and dropping."
Dr Mace said the research that had been done was of a high standard and anecdotal reports of good catches in some areas did not reflect the true situation.
"There is significant evidence that blue cod do not migrate at any stage in their life cycle. This highly territorial nature of blue cod makes them susceptible to localised depletion, which is what we are currently seeing in the Marlborough Sounds," Dr Mace said.
In July the Minister of Fisheries announced that enclosed waters of the Marlborough Sounds would be closed to all recreational blue cod fishers until 2012.
The temporary closure was aimed at relieving fishing pressure on blue cod stocks and allowing time for Marlborough Community to develop a management plan to protect the stocks in the future.
