Ben Crichton M.Sc. Project: Whitebait fishery and populations dynamics of kōkopu

Ben’s research seeks to answer the elusive question of whether whitebaiting impacts the population dynamics of harvested kōkopu species and whether closing areas to whitebaiting contributes to species protection and increased production. To achieve this, Ben will monitor banded, shortjaw, and giant kōkopu populations within whitebaited and legally closed waterways on the West Coast of the South Island each month for a year. Using spotlights, the nocturnal kōkopu are caught at night with hand nets and placed in buckets to be measured. Environmental variables, such as pool volume and bank cover, are… Read More

Whitebait spawning sites in Kaikōura’s rivers

Early in 2019 we started work to fill a knowledge gap about whitebait in streams and rivers along the Kaikōura coast. For īnanga, which makes up the bulk of the whitebait catch, the spawning grounds are usually found close to the coast near the river mouths. Knowing where they are is useful for recovery planning in the same areas post-earthquake as well as for restoration projects in local waterways. Our survey programme started with fish trapping to find out which species were living in which rivers, after which we selected waterways that… Read More

Whitebait hatching experiment with Environment Canterbury

Our discovery of whitebait spawning sites in Kaikōura streams (see Recover Issue 3) ended with a twist in Waikoau / Lyell Creek when we realised that the eggs were unlikely to hatch. Thanks to Pete Adams at Environment Canterbury we came up with an engineering experiment in the form of a temporary closure — the reverse of mechanical stream openings that are routinely used to alleviate flood waters backing up after natural river mouth closures. In this case we temporarily blocked the mouth with gravel to raise the water level around 40… Read More

Stuff article on Kaikōura whitebait

Great article by Sophie Trigger at the Marlborough Express that features our recent work investigating earthquake impacts on river mouths along the Kaikōura coast. We were able to locate several whitebait spawning sites and made some interesting discoveries with many of them occurring on flood events. Read more about an ecological experiment to rescue eggs stranded high on the riverbank with the help of the Environment Canterbury flood management team here

Whitebait spawning in Lyell Creek Waikōau

Nice article in the Kaikōura Star on our surpise finding of whitebait spawning sites in downstown Kaikōura. The spawning habitat in this area has benefitted from riparian restoration work in Lyell Creek / Waikōau since the earthquakes.

Inanga ora ki te awa o Waitara

It’s been great working on this project with Waitara Alive and the Ōtaraua Hapū along with Waitara High School students to better understand the health of whitebait spawning sites along the Waitara River. The project is comparing present day spawning site health and abundance to historical evidence collected from local kaumatua. By contrasting past with present, the Inanga Ora project team hope to identify how spawning habitat is changing, and what can be done to better protect it.The project was funded by the ‘Curious Minds’ He Hihiri I Te Mahara. Participatory Science Platform.Check… Read More

Earthquakes cause shifts in the location of whitebait spawning

The story of how whitebait spawning sites shifted to new areas after the Canterbury earthquakes – and then became exposed to new vulnerabilities from the pre-existing pattern of land use.This spatial ecology study reveals how and where we can take action to protect whitebait spawning sites! Read more here

Using artificial habitats as a natural habitat detection tool

We have a new paper published in the journal Ecological Indicators that describes the science behind using artificial habitats (such as straw bales) to as a detection tool. We used this approach to help identify īnanga spawning habitat in degraded waterways where egg mortality can make it difficult to find the eggs directly. Read more here

NZ’s largest known area of inanga spawning found in Christchurch waterways!

An unexpected result of our earthquake studies was the discovery that  īnanga spawning habitat had expanded, and was more extensive than ever previously recorded in Christchurch’s waterways. Further surveys in 2016 found that even larger areas were being used. The total area of spawning was around 2x the next largest area recorded anywhere in New Zealand !

New methods paper – Census survey approach for īnanga spawning habitat

Waterways and MERG have recently published details of a survey methodology for locating and mapping īnanga spawning sites near coastal rivermouths.  Read more here.

New spawning sites found in Aromahana Lagoon in Greymouth

Mike Hickford and Shane Orchard recently visited an community restoration project on Cobden Island in the Grey River and nearby Aromahana Lagoon. Our main goal was to scope out a survey strategy for monitoring īnanga spawning in this area. Time was short but we did manage to find two new spawning sites.  This is an innovative floodplain restoration project on an impressive scale. Thanks to Henk Stengs at DOC for showing us around!

Spawning habitat maps for Ōtautahi waterways

These maps show results from two years of spawning site surveys plus two years of straw bale experiments in the waterways of Ōtautahi Christchurch. Compare them with the Whaka Inaka maps where we took all of the known sites at the end of 2015 and tested if there might be others both in the gaps and further upstream/downstream. And yes there were.These maps are available as free downloads. There’s some other maps available too ..check them out here There’s a lot of data behind these dots. In the coming months we’ll be processing… Read More

Resilience research on whitebait featured in UC Chronicle

The September 2016 issue of the Chronicle He Kupu Whakamahara ran a story on our research into the resilience of whitebait spawning sites in Ōtautahi Christchurch following the earthquakes. Follow the link here to the article online Some recent publications relating to this work: Earthquake effects on spawning sites – download the original report here Identifying īnanga spawning sites in plans – short report available here Census survey approach to quantifying īnanga spawning habitat New Zealand Journal of Marine and Freshwater Research, 52(2), 284-294. Earthquake-induced habitat migration Aquatic Conservation: Marine and Freshwater Ecosystems, 2018; 1-11.

Earthquake effects on whitebait spawning sites

The Waterways Centre for Freshwater Research and the Marine Ecology Research Group are pleased to provide a new report on the distribution of īnanga spawning sites in Ōtautahi Christchurch. Thanks the Engineering New Zealand / Water NZ Rivers Group for supporting this work.Highlights include comprehensive information on changes in relation to the Canterbury earthquakes, and a summary of the key implications for waterways management.