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More spawning for Christchurch Whitebait


30 January 2016

In the largest-scale initiative of its kind, on Saturday, Whaka Inaka project leaders, local businesses, community volunteers and teams from the local Ngāi Tahu hapū (Ngāi Tūāhuriri) installed 192 straw bales along the lower reaches of the Ōpāwaho/Heathcote River and around Lake Kate Sheppard (between Travis Wetland and the Ōtākaro/Avon River). Designed as a ‘hotel hilton’ for īnaka, these bales will provide much-needed spawning habitat for the only whitebait species found in Christchurch.

Christchurch was once well renowned for its abundant īnaka spawning, but changes to the river banks where they spawn has meant that legacy has been in decline for some time. Changes wrought by the earthquakes has also potentially changed where along the river they spawn, as they only spawn in the area around the upper limit of the saltwater wedge.

“By laying their eggs in vegetation along the banks during the highest ‘spring’ tides, īnaka can keep their eggs safe from predators in the river. But that makes them more vulnerable to changes to the riverbanks where they spawn” says Dr. Mike Hickford, research biologist at the University of Canterbury (Marine Ecology Research Group), and project partner for Whaka Inaka. “Such changes have contributed to a decline in the spawning success of īnaka in Christchurch”.

The straw bales provide ideal conditions for īnaka (Galaxias maculatus) to lay and hatch their eggs over the spawning season (February-May). “The bales are easy to install and monitor, and along with improving spawning success, they will highlight where along the rivers īnaka prefer to lay their eggs in the post-earthquake environment”, says Project Leader and principal scientist at EOS Ecology, Shelley McMurtrie.

The project looks to build greater awareness and understanding of the habitat needs of īnaka through engaging local businesses, community, and those who manage the city’s waterways to help inform their practices in favor of this much loved fish. “We all have a part to play in the future of the city’s whitebait population through effecting positive change in the way we care for the riverbanks where these iconic fish spawn”, says Shelley.

Increased spawning will help to bolster the number of whitebait coming back into East Coast rivers. “Imagine how positive it would be for Christchurch’s well-being and wealth if the city’s two principal rivers were full of whitebait every spring. People love to see fish in their rivers. It captures our attention. It’s good for the soul, and could well lead to healthier puku and pockets” says Te Marino Lenihan of Ngāi Tūāhuriri, and project partner for Whaka Inaka.

Arapata Reuben of Ngāi Tūāhuriri notes that "Kaiapoi Māori have had a long association with the Ihutai estuary and its rivers. The kaitiaki [guardian] of the Ōpāwaho [Heathcote] and its surrounds was my ancestor Te Muru who resided in Kaiapoi and Koukourtarata [Port Levy]. In 1880, before the Smith-Nairn Royal Commission, his son Wiremu Te Uki claimed these rivers and their resources on behalf of Kaiapoi Māori.”

Egg counts of the bales will be done monthly by EOS Ecology scientists through the spawning season, and is aimed to dovetail with wider work on post-quake spawning being undertaken by Shane Orchard of the University of Canterbury (Waterways Centre for Freshwater Management, Ngāi Tahu Research Centre).

Whaka Inaka has been funded by the Department of Conservation through their Community Fund, and has received support from a number of trusts, organisations and local businesses. The project is a collaboration between EOS Ecology (project lead), Ngāi Tahu, and the University of Canterbury. Find out more about the project and its supporters here and at the project Facebook page.

200 straw bales being delivered to Gelita
In December 2015 over 200 bales were delivered to the stockpile site at Gelita, with the help of City Care, EOS Ecology and Gelita staff. Photo © EOS Ecology. grey-BR
Whaka Inaka installation day briefing
Gelita was the base of operations for the installation day, which went off without a hitch. Photo © EOS Ecology. grey-BR
Whaka Inaka installation day group photo
45 people turned out for the installation day on the 30 January 2016. Photo © EOS Ecology. grey-BR
Installing the straw bales
192 bales were installed along the river by eight teams led by people from EOS Ecology, University of Canterbury, K4 Cultural Landscape Consultants, and the Department of Conservation. Photo © EOS Ecology. grey-BR
Whaka Inaka sign at monitoring site
Signs installed at each bale site tell people about the programme. Photo © EOS Ecology. grey-BR

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