University of Massachusetts Amherst ScholarWorks@UMass Amherst International Conference on Engineering and International Conference on River Connectivity Ecohydrology for Fish Passage (Fish Passage 2018)

Dec 13th, 11:00 AM - 12:40 PM Use of built barriers in New Zealand streams as a conservation management tool Sjaan Bowie Department of Conservation, Christchurch, CANTERBURY, New Zealand

Daniel Jack Operations, Department of Conservation, Dunedin, New Zealand

Dean Nelson Operations, Department of Conservation, Twizel, New Zealand

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Bowie, Sjaan; Jack, Daniel; and Nelson, Dean, "Use of built barriers in New Zealand streams as a conservation management tool" (2018). International Conference on Engineering and Ecohydrology for Fish Passage. 25. https://scholarworks.umass.edu/fishpassage_conference/2018/December13/25

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International Conference on River Connectivity, 10-14 Dec, 2018, Albury, Australia Presentation at Fish Passage 2018

Sjaan Bowie 1 , Daniel Jack 2 , Dean Nelson 3 1 National Freshwater Team, Department of Conservation, Christchurch, NZ [email protected] 2 Operations, Department of Conservation, Dunedin, NZ 3 Operations, Department of Conservation, Twizel, NZ NZ’s freshwater fish need help

• 54 native fish (72% threatened/at risk) • 1 extinct • 21 exotic species

• >50% resident • 100% non-migratory galaxiids threatened/ at risk

Dunn, N.R., Allibone, R.M., Closs, G.P., Crow, S.K., David, B.O., Goodman, J. M., Griffiths, M., Jack, D.C., Ling, N., Waters, J.M., and Rolfe, J.R. (2018). Conservation status of New Zealand New Zealand Freshwater fishes, 2017. New Zealand Threat classification series 24. Wellington, New Zealand: Department of Conservation. Threats

• Habitat degradation & loss o Land-use (agriculture & forestry) o Water & gravel abstraction o Macrophyte invasion • Predation & competition

Up to 37% of known habitat has been lost 4 Invasive species of concern • Greatest risk Koi carp, perch, catfish, gambusia, rudd, brown trout & rainbow trout in particular locations

• Others under certain locations & conditions including some natives e.g. eels, kōaro

Franklin, P., Gee, E., Baker, C., Bowie, S. 2018: New Zealand Fish Passage Guidelines for structures up to 4 metres. NIWA client report 2018019HN, Hamilton. 226p. Rowe, D.K., Wilding, T. (2012) Risk assessment model for the introduction of non-native 5 freshwater fish into New Zealand. Journal of Applied Ichthology, 28: 582-589. Non-migratory galaxiids & mudfish • Key threat - invasive species • Varying level of pressure.

Most impacted – Restricted to headwaters – Small streams – Fragmented locations – Low fecundity/ large egg – Limited dispersal Without natural waterfalls & built barriers these species are in real trouble Key conservation tool

Shown success internationally NZ - 15+ partial or full built barriers

• Protect key hotspots • Enhance, protect or enable restoration of key habitats &/or communities

++ + + + + ++ + + + 8 When can barriers be considered?

• Invasive species are impacting on a location that supports key species or habitat • Barrier protects or see’s the recovery of species or habitats • Won’t impact life history, fragmentation, loss of genetic mixing or cause hybridizing • Feasible: – removal of invasive fish – prevention of future new invasions – viable in prevailing environment 9 What we know works:

Shallower downstream slope

Moderate gradient stream bed

Minimum fall height > 1.5 m Small drops (< 2.5 m) should be combined with other barrier mechanisms V-notch crest profile

≥ 500 mm overhangs to inhibit jumping

10 Charters, F. (2013) Waterway barrier design for protection of native aquatic values. Report prepared by University of Canterbury for Department of Conservation. Christchurch: 54. We need to understand the fish - Example • Trout & koi carp can jump Source Cindy Baker

• Some native fish can climb Source Josh Tobak So • Height of structure & lack of depth downstream can be provided to prevent jumping • Grates or overhangs can be added to prevent or enable climbers or swimmers

Source Adam Daniel Design Overhangs/ perched (>500mm) Chutes (High Fall (>1.5m) velocity zones)

Low water depth; d/s apron Minimise up/s backwater Screens

• Weir barriers are the most successful • Excluded salmonids, kōaro, koi carp, perch, Gambusia, goldfish & rudd • Silt & water build up – v-notch, drop log, perch culvert, or pipe with stopper within weir Trout barrier Akatore Creek

1.75m waterfall

Site features Natural waterfall

Aim Protect resident native fish - Taieri flathead galaxias

13 Trout barrier Akatore Creek

Barrier features Full barrier Placement on top waterfall Drop log structures to manage flow & sediment flushing

Result No brown trout observed since 2012 Monitoring critical Trout barrier Omarama Spring

Site features Low head/slope, small spring feed stream feeds into braided river Barrier features Full barrier Placement in stable section Smaller drop so perched culverts Downstream apron Aim Protect resident native fish

Result Brown & rainbow trout removal continuing Schools of non-migratory galaxiids seen Kōaro barrier Upper Waipori tributary

Site features Existing weir Barrier features Full barrier Smaller drop so add lip V notch – concentrated flow, water levels can be managed Downstream apron Overhanging structure to prevent kōaro (landlocked)

Aim Protect resident native fish - dusky galaxias Kōaro barrier Upper Waipori tributary

Result Kōaro lip too small/ splash zone Revised kōaro lip install (no splash, more angle, tight seal) Dusky galaxias numbers slowly increasing

Source; Josh Tobak Trout & Kōaro Barrier Fraser Spring

900 mm high

1.2 m concrete pad

Site features Low head/slope, spring feed stream Barrier features Full barrier Placement in stable section Smaller drop so add lip Downstream apron Aim Protect resident native fish Trout & Kōaro Barrier

Annual monitoring in Nov/Dec at Upper Fraser Spring Site Bignose galaxias Result 120

Lowland longjaw 100 Koaro galaxias Trout excluded removal Brown trout Barrier/ Upstream pool created 80 Trout removal Koaro Small lip not effective; changed 60

Bypass culvert with stopper 40

not successful Totalnumber fish of caught 20 Silt & macrophyte 0 establishment 2004 2006 2008 2010 2012 2014 2016 2018

-20 Fish recovering Year Koaro increasing; removal Removal Removal Trout 90 • Feasibility of site 80 70 60 • Method 50 40 30 – Electrofishing + nets 20 10 – Minnow traps 0 • Effort

20 Still learning • Built barriers are an effective conservation tool • Maintenance & monitoring is essential • Experienced staff critical for invasive fish removal • Electrofishing eradication possible in small streams • Successful design features have been identified • Some barriers features unsuccessful – Gabion baskets – Some lips for climbers • Costs $5000 - $100,000 plus man hours

…. we are still learning Thanks for listening

Questions?

Sometimes the natives get revenge ☺

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