Co-location, Co-location, Co-location:

Enabling an “Esk-ape to the country”?

R.A. Noble, J. Dodd, S. Walton, J.D. Bolland

& I.G. Cowx

J. Hateley, P. O’Brien, M. Reid, J. Gregory

A study of the performance of a Larinier fish pass co-located with a low-head hydropower turbine on Ruswarp Weir at the tidal limit of the Yorkshire Esk

Ruswarp Weir – Co-located fish pass & Turbine

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Ruswarp Weir – Co-located fish pass & Turbine

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Before:

Pool-traverse pass

After:

Larinier passLow-head 50 kW HP(max 4 cumec abstraction)

Ruswarp Weir

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Flow

TidalBaulk fish pass

Main Fish pass

Model 290 acoustic tag receiver Acoustic Tracking System

Model 300 mobile hydrophones

Hydroacoustic Technology Inc., Seattle, USA

Study design – post commissioning

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HTi ATS Array

HTi Remote hydrophonesPost Commissioning Monitoring Only

Release site

Model 795LG acoustic tags

All tagging done under Home Office LicencePPL 80/2411

Coarse-scaleFish passage metrics

Fates of tagged fish – post commissioning

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Attraction efficiency?

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“Attraction efficiency”

Post- = 62%

Baseline = 35%

Detected in Array

Not detected in Array

Totals

Baseline 17 31 48

Post- 81 50 131

Totals 98 81 179

Chi-square Test for Independence (Frequency Distributions)

Chi-square = 9.894d.f. = 1p < 0.01

Highly significantly different

Overall passage efficiency?

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“Overall Passage efficiency”

Post- = 47%

Baseline = 35%

Passed Weir (LFP+ BFP)

Did not pass Weir

Totals

Baseline 17 31 48

Post- 61 70 131

Totals 78 101 179

Chi-square Test for Independence (Frequency Distributions)

Chi-square = 1.776d.f. = 1p > 0.05

No Significant difference

“Attraction/Passage Efficiency” – influence of return rate?

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YearBehaviour/Detections 2013 2014 2015n sea trout tagged 46 44 41% First detected in Whitby 26% 25% 49%n later detected at Ruswarp 6 3 3% re-ascending river 50% 27% 15%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

15/10 01/11 18 &22/11

16/10 04/11 10/11 18/11 30/10 9/11 16/11 23/11

2013 2014 2015

% o

f ta

gg

ed fis

h

Batch / Year

Total in Array n logger only n 0 Records

23 13 8 13 9 9 13 12 4 17 8

Attraction/Passage Efficiency – post commissioning

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81 went on to enter the array

Attraction efficiency = 96%

Overall Passage efficiency = 73%

61 ascended the weir via any route

84 tagged sea trout returned to the weir

Fish pass efficiency?

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Fish Pass efficiency

Post- = 67%

Baseline = 100%

Array -LFP

Array (BFP or DNP)

Totals

Baseline 17 0 17

Post- 54 27 81

Totals 71 27 98

Chi-square Test for Independence (Frequency Distributions)

Chi-square (Yates’) = 6.241d.f. = 1p < 0.05

Significant difference

Fish behaviour:

Searching behaviour&

Delay

Time spent searching

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Median total time from first to last array detection:

Larinier Passage2.6 (0.6 – 18.1) hours (n = 54)

Non-passage34.7 (5.8 – 78.3) hours (n = 20)

Baulk Passage9.2 (0.8 – 186.6) hours (n = 6)

Noble’s Yard

Array

Travel time from Noble’s to ArrayMedian 24.7 (19.1 – 39.9) minutesMinimum 4.8 minutes

Number of visits to the array13.6% pass on 1st visit41% had more than 5 visits before passage

~ 195m

Time spent in the array

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Median total time spent in the array by sea trout prior to passage:

Post commissioning26.4 (2.4 – 76.9) minutes (n = 54)

Baseline4.8 (1.5 – 27.8) minutes(n = 17)

(Mann Whitney U-test: Z = 2.237, n = 71, P <0.05)

Duration of individual tracks:Baseline median = 3.6 (1.6 – 9.5) minutes Post-commissioning median = 2.9 (0.8 – 8.2) minutes

Time from first array detection to passage

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The median time from first detection in the array to passagePost- = 2.7 (0.8 – 17.3) hrsBaseline = 0.3 (0.1 – 1.4) hrs

(Mann Whitney U-test: Z = 3.153, n = 71, P <0.01)

0

2

4

6

8

10

12

14

16

Num

ber

of fish

2011 2012

0

2

4

6

8

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12

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16

1 2 3 4 5 6 7 8 9

10

11

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24

48

72

96

120

>1

20

Nu

mb

er

of fish

Time between detection and H8 (Hours)

2013 2014 2015

Fish behaviour:

Fine-scale behaviour at the pass

2D Tracking Analysis

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FP

HP

FP

HP

FP

HP

Simple –Passage

Simple –Non-Passage

One or more approaches?

FP

HP

FP

HP

Resting –no approaches?

Non-passage –Distraction?

Evidence of attraction to:

HP outflow?

Deeper water?

Is this evidence of distraction or resting/refuge?

Spatial Use of the Pool

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Baseline Post-commissioning

Occupation of the Pool

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Baseline Post-commissioning

Timing of passage in relation to generation

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• Hydropower turbine active for 63% of the time (varied between years)

• Operating at near capacity (abstraction > 3.5 m3s-1) for 19.8% of the time during tracking period

• Sea trout were observed to ascend through the fish pass under most conditions

• Three sea trout passed whilst the turbine was off

• 42% of tagged sea trout passing at turbine flows of greater than 3.5 m3s-1

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0

10

20

30

40

50

60

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80

90

100

Hydro

pow

er

flow

m3s

-1

Exceedence %

Hydropower flow 2013 2013 Passages

Hydropower flow 2014 2014 Passages

Hydropower flow 2015 2015 Passages

1/9 - 31/12 flows

Flow & HP abstraction

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0 m3s-1 (Off)n = 37

0.01 to 1.00 m3s-1

n = 41

1.01 to 2.00 m3s-1

n = 62

2.01 to 3.00 m3s-1

n = 74>3.01 m3s-1

n = 76Use of the pool under different HP activity –

River flows <Q25(6.28 m3s-1)

~ Overtopping of weir

Track distribution/duration in relation to flows

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Abstraction > 2 m3s-1

Discharge Q25 to Q15

n = 217

Abstraction > 2 m3s-1

Discharge Q15 to Q10

n = 59

Abstraction > 2 m3s-1

Discharge > Q10

n = 76

Conclusions

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1. “Passage Efficiency” varied greatly between years - no significantdifference after commissioning of the turbine

• Influenced by return rate

• Passage efficiency 73% post-commissioning

• “Passage at the site maintained”

2. “Attraction Efficiency” - significantly higher post-commissioning

• Influenced by return rate

• Attraction efficiency 96% post-commissioning

3. “Fish Pass Efficiency” - significantly lower post-commissioning

• Is 67% passage of sea trout an adequate performance for a Larinier pass at head oftide?

Conclusions

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4. The delay between arrival in the pool and eventual passage, whilst statisticallysignificantly greater post-commissioning, is of little energetic consequencegiven the overall scale and duration of the sea trout migration.

• However, it is possible that longer delays did have consequences for successfulpassage.

5. Some evidence of attraction of fish to the area in front of the hydropoweroutfall screens - most apparent when the turbine was active at flows <Q25.

• Caused by sea trout seeking refuge in deep water or being distracted from the fishpass plume by the outfall from the hydropower screw?

6. No evidence to suggest that any of the changes and variability in the passagemetrics and the delay in passage through the main fish pass can be solelyattributed to the activity of the hydropower turbine.

Thank you