Whangamarino Wetland & Botulism Outbreak

I see in the recent article from Andrea Vance published by Stuff on 19th March 2023 that she is discussing the outbreak of avian botulism causing thousands of bird deaths within the Whangamarino area.

“A strange silence has gripped Whangamarino. It’s a deathly silence.

The corpses of thousands of dead birds have piled up around the extensive mosaic of swamps, fens, bogs and open water between Waikato’s Meremere and Te Kauwhata.

The wetlands are usually an oasis for rare wildlife. It is home to the largest population of Australasian bittern, or matuku, in the world, and its booming calls echo across the water.

But large populations of Whangamarino’s birds have fallen sick with avian botulism, dying a gruesome death after they have lost the ability to walk and use their wings.”

Wetlands play a vital ecological role and providing unique habitat for threatened plants, birds, and fish; they also improved water quality, and reduced flood risks to nearby communities.

But in the Whangamarino Wetland, a RAMSAR site, a weir was built in in the 90s on the Whangamarino River jointly by the Department of Conservation (DOC) and Fish & Game (F&G). The weir was designed to artificially raise and control water levels because the environmentalists believed that wetlands should be wet all the time. This is not the case. No consideration was given to the environmental desecration of both the Highmore flora and fauna and the birdlife nesting sites within the dry swamp floor by flooding the swamp.

Artificially keeping the water levels high also prevented the natural flushing actions related to natural weather conditions and has reduced the water quality rather than improving it. Raising the water level in the swamp has caused sediment issues as the dammed water has spread out into the swamp and deposited silt that would naturally flow down the river. The lack of any natural flushing also greatly increases the potential for the wetland waterways to become anoxic and kill more native flora and fauna.

Prior to the Weir construction, the Whangamarino wetland was an outstanding example of a Highmore Peat Dome – or dry peat swamp that became a wetland in the winter. Historical evidence from early settlers confirms how dry it was in summer and how they used to walk across the swamp to the Whangamarino railway station which used to be on Wattle Rd. Some earlier settlers grew barley in the swamp.

There was I believe another motive in seeking higher water levels. Fish and Game have since created a lunar landscape of duck ponds around the wetland and needed higher water levels to make these attractive to duck shooters during the duck season. It provides F&G with a lucrative form of revenue as the larger the wetland area, the greater numbers of hunters that will rent ponds and buy hunting licences. I understand that F&G also supported the release of Canada Geese (another invasive pest species) in the area.

Unfortunately the higher water levels created also allowed the Koi Carp more area to both feed on and lay their eggs. This compounds the detrimental effects by breeding larger numbers of Koi Carp. The higher water levels also allow the Carp to feed in more areas of the wetland further damaging the wetlands. The feeding actions of the Koi Carp cause sediment disturbance and erosion releasing quantities of nutrients into the waterways adding to nutrient loadings. In a study in 2003/2004, 85% of the carp entering Lake Waikare came up the fish passage from the Whangamarino Wetlands. Lake Waikare has been decimated by huge carp numbers in recent years.

When the Weir resource consent was granted, concerns were expresses about adverse impacts. DOC and F&G were given strict monitoring conditions as a result. They have never complied with some of the monitoring conditions relating to the operation of this weir. Waikato Regional Council has taken no action to enforce the consent and it is unacceptable that the requirements of the resource consent conditions imposed on both DOC and F&G were not enforced with the same rigour that Council sees fit to impose on other consent holders.

The findings of the recent report commissioned from Dr Doug Edmeades is that the majority of the phosphate and sediment that is coming from the Lake Waikare and Whangamarino catchment is actually coming out of the wetlands through bed disturbance by carp and not from the agricultural areas in this catchment

Water samples tested at the entry points from the surrounding farmland areas have been shown to be well within the average levels for contaminants. However samples taken from the discharge point of the wetland where it enters into the Waikato River show much greater levels of Sediment and Phosphorous but with reduced levels of nitrates.

The natural assumption that we (P.L.U.G.) take from these results is that the feeding actions of the Koi Carp are raising the levels of sediment and nutrients within the wetland creating the large increase in these levels at the discharge point. Waikato regional Council has failed to include in their Proposed Plan Change 1, a coherent strategy to remove the pest fishes from all of the waterways in the Waikato Region.

We believe that DOC and F&G who are supposed to be the protectors of the wetlands have in fact significantly contributed to the degradation of this wetland through their decision to install the weir in the Whangamarino River. They have compounded this by failing to adhere to the conditions of their resource consent. Rather than put their own house in order, they are publically blaming the surrounding land users for their problems.

Chief Executive of Fish & Game, Corina Jordan said even freshwater eels, which are hardy and able to tolerate low-oxygen environments for short periods, had perished.

We are concerned at the rhetoric we hear from authorities labelling these incidents as natural, Jordan, who is a freshwater ecologist, said. Parts of this wetland have been without oxygen for the best part of three months, leading to massive aquatic deaths of even the hardiest freshwater species such as eels. This isn’t normal in healthy freshwater wetland systems.

Jordan said the council must now take a “hard look” at how the catchment is managed and limit discharges into the waterways. She also wants to see a long-term plan for managing Whangamarino.

In her previous position as General Manager for Beef and Lamb NZ Jordan was informed of the results of Dr Edmeades report on the water quality of the farm runoff into the wetland and as a freshwater ecologist and who has since 2008 spent 6+ years as Planner and Freshwater Ecologist with F&G, 2 years as General manager F&G, 5+ years as Environmental Policy Manager (NI) B&L NZ, 2years as General Manager B&L NZ should have been able to identify the issues of poor water quality that are associated with Koi Carp and that these are the same issues that can lead to low oxygen levels in affected waterways.

The Vance article published by Stuff went on to say that;

Now, appalled by the outbreak, Fish & Game New Zealand has launched a stinging attack on Waikato Regional Council, accusing the local authority of permitting dairy intensification and failing in its statutory obligation to protect freshwater environments.

Fish & Game chief executive Corina Jordan said the disease outbreak, which is in its third month, was “appalling” and a wake-up call for “urgent action”.

Devastated Fish & Game staff, as well as community volunteers, has collected almost 2000 birds, including matuku, in the last month.

Although classed as internationally significant, the wetland has long faced environmental challenges, overloaded with sediment and nutrients from farming and industrial run-off and storm water.

Poor water quality, and changes to how the water flows, has contributed to low oxygen levels in the swamp.

The article blames overloading with sediment and nutrients from farming and industrial run-off and storm water for this outbreak, yet the recent report from Dr Doug Edmeades proved that the majority of the phosphate and sediment that is coming from the Lake Waikare and Whangamarino catchment is actually coming out of the wetlands (most likely through bed disturbance by carp) and not from the agricultural areas in this catchment.

Central Government needs to take action now with an independent investigation into the actions of DoC / F&G and the Regional Council. All parties have contributed to the decline in water quality and the resulting decimation of an internationally recognised RAMSAR Highmore wetland. They need to be called to account for their actions or lack thereof.

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