Long Bay - Okura Marine Reserve Cockle Death Results Now Public

Results of a study to determine why hundreds of thousands of shellfish have died in the Long Bay Okura Marine Reserve in March of this year, have been released by the Ministry for Primary Industries and point to environmental stress.

The Ministry for Primary Industries’ Scientist reports “Basically, the results do not show evidence of an infectious process, but are consistent with animals dealing with a lot of environmental stress which would be expected from living in an estuary and having to deal with constantly changing salinity, water temperatures and other environmental insults such as possibly sedimentation, or eutrophication”.

These recent deaths follow two earlier shellfish die-offs, recorded by the Marine Reserve’s watchdog, the Long Bay Okura Great Park Society. Its members have been monitoring silt levels for over a decade. The Society has documented heavy sediment loads going into the Marine Reserve for the last 2 years so it is not surprised by the results.

Peter Townend, spokesperson for the Long Bay Okura Great Parks Society says “The Marine Reserve is showing signs of stress, with biodiversity diminishing under the impacts of increased sediment. The latest laboratory testing shows one stream alone from the Weiti development, behind Karepiro Bay, is discharging up to a massive 510 grams per cubic metre of water. That’s almost a hundred times what a healthy stream should discharge.”

While the MPI Report cannot point to any single cause as being the reason why the shellfish died, its scientist does note “that the gills (of shellfish) were often affected both with parasites and particulate organic matter – this could be compromising the animals ability to feed – and an excess of particulate matter could also cause mechanical damage to the gills, again compromising the animals ability to feed.”

Mr Townend states “Shellfish are our filter feeders. They are hugely important for a healthy marine environment. We have acres of dead and dying shellfish. It is horrifying and we need to act fast.”

“The Society is calling for an urgent review of all Council consents within the catchment. Many consents given by Council have no limits on the volume of sediment that can be discharged. This means, in some cases, developers are discharging tens of tonnes of sediment into the Marine Reserve in one single rain event.”

The Long Bay Okura Marine Reserve is one of the six marine reserves in the Hauraki Gulf and is one of the most accessible Marine Reserves to Auckland City. With the Okura Bush Walkway on its northern banks visited by 35,000 people each year and Long Bay Regional Park receiving over a 1 million visits per annum, it offers a much-valued experience of semi-wilderness, as well as opportunities for scientific research.

Mr Townend exclaims “The Marine Reserve is a special jewel. We can’t afford to lose this place of natural wonder.”

ENDS

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