Urgent need to better protect rapidly declining Southland wetland

Wednesday, 19 December 2018

Wetland loss adjacent to Awarua Wetland Ramsar site, Southland, pictured in about 2009. The brown area is the wetland that was cleared and drained.

Southland has lost nearly a quarter of its wetland area since 1990, scientific evidence shows.

A new report on long-term wetland loss in the New Zealand Journal of Ecology that analyses and compares satellite images of wetlands taken in 1990 and 2012, shows evidence of long-term wetland loss, which has prompted an urgent call for better protection from Conservation Minister Eugenie Sage.

Southland has lost 23 per cent of its wetland in the past 28 years, according to a scientific study. Pictured, the wetland area around Waituna Lagoon near Invercargill.

Sage said: 'The study's timeframe is significant. After 1990, legislative tools were put in place to help protect the natural environment such as the Resource Management Act 1991, and agencies such as the Department of Conservation (DOC) and regional councils were formed.

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'Ideally, the rate of wetland loss would decrease with legislative protection, but in fact the report says the rate of wetland loss in Southland has been 0.5 per cent per year since 1990 – that's a rate of 157 hectares lost per year. And if we add areas that have been partially drained, the rate goes up to a 1 per cent decline per year.'

It covers a longer timeframe than any other Southland wetland loss study.

The report shows that of the 32,814 hectares of wetland in the study area, 3452 hectares have been completely lost and a further 3493 hectares are at risk because of drainage and declines in vegetation. This represents a 23 per cent decline since 1990.

Mapping indicates that conversion from wetland to agricultural and horticultural land uses accounts for 60 per cent of the wetland loss and 97 per cent of the wetland loss or degradation has occurred outside conservation reserves and was predominantly on private land.

Waituna dairy farm owner Raewyn van Gool said it was easy to blame farming, without taking into account what environmental consciousness was like pre-1990s.

'It's very easy to criticise what's gone before but we have to understand the social climate then, and understand who we were, who we are now and what we need to do going forward.'

Other natural factors that contributed to wetland decline needed to be taken into account, she said.

'Yes, we do need to look after our wetlands, but we need to understand all the underlying reasons for the loss.'

Climatic factors, such as three dry winters in a row, could have had an impact, she said.

van Gool's farm was in the catchment for Fonterra and the Department of Conservation's initiative Living Water, which was set up to improve water quality and promote creation of wetland areas.

It was represented on the Whakamana te Waituna Charitable Trust, along with Ngāi Tahu, Te Rūnanga o Awarua, Environment Southland and the Southland District Council.

The trust was formed in February to co-ordinate a five year $13.3 million programme to improve water quality and biodiversity, support cultural aspirations and sustainable farming in the catchment.

The Waituna waterway and lagoon was designated as a Ramsar Wetland of International Importance in 1976, with the wider wetland complex being included in 2008.

Sage said great restoration work was being carried out by DOC, councils, community organisations and some private landowners, 'but we're still seeing substantial and ongoing loss of wetlands. The trend must be reversed so we don't lose wetlands altogether'.