### Design 

## and Testing Specification for 

## a Fish Deterrent 

## Bubble Barrier 

## for Heysham 

## Power Stations 

## 1 & 

### 2



## AWH Turnpenny & 

### PA Henderson



### Client: 

### Mr 

## KS White, Station Mhnager, Heysham 

## 2 Power Station

Report 

## No. FCR006192 

## March 1992

Approve Turnpenny (Managing 

### Director)

Date:



# ..................... 

# IQGi2, 

# \.r&d@&SUMMARY 

### This Report reviews expedence elsewhere of 

### the use of bubble curtain barriers for fisheriesapplicationsand, 

### inparticular, their suitabilityfor excluding

### fishfromwater intakes. Theuse of augmentary stimuli, such as underwater strobe lights and sound generating systems, 

### aimed at 

### enhancing the effectveness of bubblebarriers for fish exclusion, 

### is also discussed. TheReportthenprovides

### a specification

### for the designand testingof 

### a fishprotection barrier system for Heysham Power Stations 

### 1 and 

### 2.

CONCLUSIONS AND RECOMMENDATIONS 

### Bubble Curtains and Augmenting Stimuli
0 Bubble curtains have been used effectively as fish barriers under certain conditions.

0 For fish protection at water intakes, it 

### is advantageousto angle the barrier relative to the flow, 

### so that fish 

### are guided to a safe 

### area at one end 

### of the barrier.
0 Bubble barriers rely primarily 

### on 

### a visual response by 

### fish and 

### so are more effectivein daylight. Strobelight systems 

### canbeused effectively to 

### improve the over day 

### and night, but 

### are likely 

### to be impractical at Heysham due to frequent (weekly) inspection and maintenancerequirements. Vnderwater sound offers a more promising augmentary stimulus, 

### with high system reliability and low maintenance costs for a well designed system. Combined 

### with a bubble barrier, it should be possible to achieve high diversion efficiencieswith well-controlled sound distribution. 

### Bubble Barrier Design 

### Parameters Therecommended design parameters for the bubble barrier 

### are as follows:

barrier line: curved, as shown 

### in Figure 3

0 barrier length


## ........................ 75m
0 bubble tube internal diameter


## ......... 50rnm bubble outlet hole size


## ...............0.38mm 0
0 holepitch


## ........................... .50mm
0
0 

### air demand


## ............................ 1.5m3min-' operatingpressure.. 

## ..................276Wa (switch-on), 

### 414Wa (switch-off)

8
0
e
0 bubble 

### tube material: semi rigid PVC or alhathene delivery tube material: spirally-reinforcedPVC hose seabed attachment: steel chain and cable ties bubble tube purging: via a gate valve attached to the end away 

### from thecompressor, out of the water augmentary stimuli: acoustic, by low frequency 

### (< 1OOHz) modulation of the 

### air supply, orusing an

### array ofelectromagnetictransducersbehind thebubble barrier, fed from 

### an onshore signal generator/amplifier system. 

### ExperimentalDesign 

### and 

### Statistics Thebubblecurtain experiment shouldbeundertaken over 

### a minimumtwelve day period in the months of October

### or November. Tidal and operationalconditionspermitting, thebest period would be the last week of October and the first week of November. 

### Once sampling has commenced it should be undertaken on consecutivedays. This 

### will require week-end work. It isrecommendedthat two working daysbe assigned at the beginning of the experimental period duringwhichthe samplingequipmentwillbeinstalledand working methods defined. It 

### is recommendedthat chlorination of the screenwells at an applied dose of OSppm should be undertaken for a period of 2-3 hours prior to each 

### trial period, to minimisethe adverseeffectsof fish storageon interpretation of the testresults. Sodiumhypochloritedosing would beadequatefor this, ifnormal station chlorinationhas been suspended. 

### To add an augmentary sound stimulus, a second, similar period of testing would be 

### required, in which the sound system and the bubble curtain were operated simultaneously,againwith alternatingdaysof operation. This would be necessary to ensure that one or other system was not redundant. Ideally, a third twelve day period would be used to operatethe sound system without thebubblebarrier, unless it were alreadydecided that a bubblebarrier would be operated there for other reasons. Any trials using 

### a sound system would require 

### an initial survey and a minimum of 

### two weeks prior 

### to the trials for installation 

### and testing. A temporary system could be installed for the period of the trials only, using 

### FAWLEY arl Ud’s mobile fish deterrent caravan. There

### is no requirementfor theinnerbarriers (shown as 

### 2 & 

### 3 on FigureAl) to be installed or 

### operational during trials with the outer barrier. It is, however, important that operating conditions should be maintained in 

### a constant state during the trials, 

### so that if they operational, then they are always operational 

### or 

### vice 

### versa. 0C0”TS

1 Introduction 

### 1.1 Background 

### 1.2 Terms 

### ofReference
2 Review of Bubble Curtain use for Fish Protection
2.1 Bubble Curtains 2.2 Bubble Curtains combined with Other Stimuli Bubble Curtains and Augmenting Stimuli: Conclusions 

### 2.3 Design Specificationfor the Heysham Outer Barrier 

### 3.1 Barrier Line 

### 3.2 Bubble Curtain Parameters 

### 3.3 Addition 

### of Underwater Sound Signals Bubble Barrier Design Parameters: Recommendations 

### 3.4
StatisticalDesign for Sampling at Heysham
4.1 Statementof Problem 

### 4.2 TheHypothesis 

### 4.3 Sampling

### Technique 4.4 Key 

### Species 4.5 Experimental Design 

### 3

4

### 1 INTRODUCTION

1.1 BackFround



### In 1989, an experimentalbubble curtain 

### was installed across No 7D CW intake of Heysham 

### 2 Power 

### Station. The originalpurpose of the barrier 

### was to repel floating debris and 

### oil 

### from the intake, and to improve the bottom silt profile. Following concern expressed 

### by the 

### MAFF SeaFisheries Officer (NW District) over 

### fish catch at the station, 

### an appraisal of the problem was made by staff of the Fawley Marine Laboratory (CEGB Technical Advice Note No. RD/TAN/VlO/015/L88), and it was proposed that 

### the effectiveness of the barrier 

### as a fish deterrent should be tested. A number of 

### trials were carried out 

### in 1989 to quantify the fish catch with and without the bubble curtain operating. These indicated some reduction of fish catch, particularlyofclupeid species (spratand herring) when thebarrier was operating, but not for other species. It was concluded that the barrier was not positioned optimally for fish protection and that better results might be expected with a barrier placed furtherupstream of the screensto influenceboth Heysham 

### 1 and 

### 2 CW 

### inlets. Since, however, a barrier position close to the intakes was considered to be more effective for silt and debris control, a triple barrier scheme (Appendii 

### 1: Figure Al) was proposed, with 

### an external barrier 

### (No. 1, Figure Al) for fish deterrence, and internal barriers 

### (Nos. 2 and 3, Figure Al) in front of the Heysham 1and 

### 2 

### CW intakes. 

### FAWLEY arlLtd (formerlythe

### MarineBiology LaboratoryofNationalPower) have been commissionedto advise 

### on the design and testing requirementsfor the external 

### (No 1) fish deterrentbarrier. 1.2 

### Terms of 

### Reference This report comprises two parts: 

### Part 1 (Sections 

### 2 & 3) is 

### the design specificationfor the outer barrier. Part 

### 2 (Section 4) is the test programme for the evaluation of the barrier 

### as a fish deterrent. The terms of reference given by Nuclear Electric were 

### as follows: 

### Design Specification for the Outer Barrier (i) The specification

### is to provide the optimised position 

### on the harbour bed for the bubble barrier line. (ii) The specification is 

### to take into account the following: (a) experienceof fish response to bubble curtain barriers elsewhere; @) currents and flow patterns, at varying tidal states in the 

### CW intake approaches (using sub-surface current velocity and direction measurements

1provided by Heysham 

### 2 Power Station (Appendix 1 ); 

### (c) any limitations imposed by harbour use and activity. 

### (iii) The specification will make recommendations on the design of the bubble 

### curtain delivery tube and 

### air flow rates. (iv) The specification

### will 

### makerecommendationsfor theprovision of augmenting stimuli such as light and sound for 

### fish deterrents. 

### Design of 

### Test Programme for determiniryf 

### the efficacy 

### of the 

### installation (i) TheTest Programmewill take into account the following:- (a) Target fish species @) Tidal ajnd diurnal variability of 

### fish (c) Seasonalvariability 

### of fish (d) The most cost effective manning regime for collection, classification, quantification and measurement of 

### fish catches. 

### (ii) The Test Programme will incorporate data recording proformas and will specify recognised statistical techniques for data analysis.

2

### 2 REVIEW 

### OF BUBBLE CURTAINUSE 

### FOR FISH PROTECTION 

### 2.1 Bubble 

### Curtains Air bubble curtains havebeen used for a widevariety of applications in the 

### sea 

### since the turn of 

### this century. Milne 

### (1970) 

### traces their history from 

### 1907, when Brasher patented a system, using a bubble curtain, to attenuate waves emanating from compressed 

### air discharges associated with sub-sea tunnelling. He describes a long subsequenthistory ofbubble

### curtainresearch and development, with activitiesranging from coastal protection (through wave height alterations); prevention of salt-water intrusioninto inland 

### canals; containmentof

### oil slicks; prevention 

### ofice formation (by causingupwellingofdeeper

### warm waterlayers); attenuation ofblast waves; water reaeration; finally, 

### and most relevant to the present application, their 

### use in fisheries. The 

### use of bubble curtains 

### in fisheries has been quite widespread since the 

### 1950s (Milne, 

### 1970). Their originalapplication was to 

### limit wave height around nets inbad weather, to prevent fish escaping from the nets and to reduce damage to 

### nets. Subsequently,bubble curtainshavebeen 

### used as 

### an alternativeto nets forherding and concentrating fish 

### within a small area, 

### from which they canbe more cost-effectively netted, or 

### to drive fish inshore, within reach 

### of coastal fishermen. In this method, a loop ofperforated flexibletube, through which 

### air isblown, 

### is drawn along the sea bed 

### in the manner of a purse seine. A typical installation used for sardine fisheries 

### is described by Smith 

### (1961). Another application developed 

### in Scotland has been the use of bubble curtains to confine farmed fish within 

### sea lochs (Copland, 1977; Stewart, 

### 1982). Bubble curtains have been seen for 

### many years as a potential solution for fish protection at water intakes, though their use has met with varied success. The idea is attractive, 

### as large intake areas can be curtained off at low cost and with no hydraulic head loss penalty. One of the earliest trials took place at a 

### British power station in 

### 1957, when a bubble screen was constructed at Uskmouth Power Station to exclude salmon smolts (CEGB, 

### 1957). The screen

### was 135 

### m in length, with holes at 

### 50 

### mm centres. In the 

### trial, as many smolts were captured 

### with the air supply turned 

### off as when 

### the curtain 

### was operational. Unfortunately, the experimentd design was flawed, since it was 

### not known how long the fish had been 

### in the screen chambers prior to impingement. The 

### trials were abandoned, owing to the small numbers of smolts present during the 

### trial period. Most later applications of bubble 

### screens at power stations are reported from North America where, again, little success has been found in site 

### trials. In 

### a four year study 

### of behaviourial deterrents funded by the Electric Power Research Institute 

### (EPRI) at Roseton Power Station (HudsonRiver) (Matousek

### et 

### al., 1988), a bubble curtain with 

### no augmentory stimulusproduced 

### no fish deterrent effect. Otherpower station 

### trials havebeen 

### similarly discouraging, 

### withno demonstrable exclusion effect (Sonnichsen

### et 

### aZ., 1973; Lieberman and Muessig, 1978; Patrick et al., 1988). A recent UK trial was undertaken by Thames Water at 

### apotable water supply intake on the River Thames. The screen has not been rigorously tested, but is believed to 3be effective 

### in reducing coarse fish entrainment 

### (G Armstrong, pers. comm.). The apparent lack of 

### success with bubble curtains at water intakes 

### is in marked contrast to findings 

### in the laboratory, where very high 'exclusion' rates have been achieved 

### in simulated intake conditions. Patrick 

### et al., (1985) recorded exclusion efficiencies ranging from 

### 5 1 to 98% for a range of freshwater and estuarine species. Exclusion efficiency dependedupon light conditions and the species tested. Two factors may account for the lack of 

### success at water intakes. First, 

### in the wild, fish are exposedto a much wider range of stimuli, and the additional stimulus of the bubble curtain may be less important than 

### in 

### an experimental set-up. Secondly, and probably most important, in most power station trials the bubble curtain has been positioned parallel to and directly 

### in front 

### of the coarse screen/trash rack assembly (as in the 1989Heysham 

### 2 trials), where water velocity is already high and fish 

### are offered little opportunity to escape. A more sensible approach is proposed by Mishchenko and Pestryakov (1986), who suggest that the bubble 

### curtain should be placed ahead of 

### the intake and at 

### an acute angle to the flow to encourage lateral diversion of fish along the faceof 

### the 

### curtain. The principle is similar to that used in other fish diversion systems and is illustrated 

### in Figure 1. Since fish 

### are not readily able to resolve 

### the 

### true direction of water flow, as they approach the angled barrier, they tend to orientate perpendicular to the barrier and swim in a direction away from it. To 

### maintain a constant distance from the barrier, they must swim at velocity 

### U,,as 

### shown in Figure 1, and consequently moveparallel to the face of the barrier at velocity 

### U,. In this way, fish are guided to the end of the barrier. 

### 2.2 Bubble Curtains combined with Other Stimuli Much morepromising results at power station water intakes have been obtained with bubble curtains augmented by sound or light stimuli. 

### Lights Whereas bubble curtains produce three types of stimulus, namely 

### visual, aural and tactile, laboratory experiments have shown that the fish herding efficiency 

### of bubble curtains is much reduced in low light conditions or turbid waters, implying that it is primarily the visual sense which is important (Blaxter and Parrish, 1965; Patrick 

### et 

### al.; 1988). It is often during the hours of darkness that fish impingement at power stations is maximal (Turnpenny, 1988)and hencebubble curtains by themselves can be expected to have limited protective value for fish over a 24 h cycle. Whilst increasing the ambient light levels improves the response of fish to bubble curtains, use of artificial illumination brings with it the risk of attracting certain 

### species (see review by Turnpenny, 1988). 

### This risk 

### can be minimised by using strobe lights employing xenon discharge tubes, operated at 

### a flash rate of 2 

### 200 flashes 

### mid, which repel rather than attract most Species of fish. 

### Barriers comprising a combination of strobe lights and bubble curtains have been used successfully both in the laboratory and at power station intakes, with higher rates of fBh deterrence than with either stimulus applied alone. 

### The usual arrangement is to

. have 

### an array of strobe lights behind the bubble curtain and projecting on to it, so that the curtain acts as a diffuser for the light. The following shows the results obtained atRosetonPower Stationforthe threepermutations (Matouseketal., 1988):

4Barrier % Fish Exclusion Air curtain -0.02 Strobe 22.6 StrObe x 

### air curtain 61.8 An enhanced effect with a bubble-curtain/strobelight combination 

### was also found 

### in laboratory trials by Patricket al., (1985). Performance may depend on site-specific factors, however, as is clear fiom the lack of success of a bubble/strobecombination 

### tested at Pickering Power Station on the Canadian Great Lakes (Patrick, McKinley and Micheletti, 1988). Theuse 

### of artificiallightinghas itsproblems, especiallywhen used in turbid estuarine waters. Where the lights are placed above the water, much of the availablelight is reflected 

### from the water surface. 

### To achieve uniform illumination, underwater placement of the lightsis essentialand, generally, a substantialarray 

### of lights 

### will be required. Once 

### in place, the lights 

### will require regular attention for cleaning of the lenses. Where strobe lights are 

### used, the short life time of the flash tubes will require that tubes are changed frequently, probably at least once per week. whist this may not be difficult 

### on shallow river water intakes, strobe lights are not likely to be a practical proposition 

### for 

### an estuarine site, 

### such as Heysham. 

### Sound One of the morepromising recent developmentshas been the use of underwater sound to repel fish. Fish are most sensitive to low frequency sounds 

### in the 

### 20-2000 

### Hz range (Hawkins, 1973). 

### To repel fish requires the attainment of high sound pressures, which must be well in excess of ambient sound levels within the same frequency band. 

### Various pneumatic and percussion devices which repel fish have been developed, and high fish exclusion rates have been reported in power station applications. 

### A drawbackof these devices is that they areprone to mechanicalfailure (Matouseket al., 1988). The availability of low frequency, high output electromagnetic and ceramic transducers, originally developed for the defense industry, offers a more reliable 

### means of generating sound suitable for fish repulsion. Using signal generators and power amplifiers, high sound levels (150-170 dB re 

### 1Pa @ lm) at frequencies of <2000 

### Hz can be generated. High reliability 

### is expected with these devices, which are intended to be operated in the 

### sea for periods of years without intervention. In 1991, acoustic deterrent trials were conductedby 

### FAWLEY arl 

### Udat Ofdbury-onSevern Power 

### Station, as 

### part of 

### thejoint National Power/Nuclear Electric aquatic research programme (Thatcherand 

### Irving, 1992). Thesepreliminary scoping trials, using a sound signal developed for bass 

### (Dicentrarchus 

### Zabrcwc) exclusion, demonstrated a 

### 30% reduction in bass catch. 

### In these 

### trials the placement 

### of the transducers was far from ideal and with improved siting, higher exclusion rates shouldbe attainable. In similar studies at inland sites in North America, Loeffelman et aZ. (1991) have achieved fish diversion efficiencies of 

### 60 to 100%. The benefits of combining sound signals and bubble curtains for fish deterrence are not evident 

### from published work (Patrick,McKinley and Micheletti, 1988; Matousek

5

### et 

### al., 1988), which has shown no further reduction 

### in fish catch when 

### a bubble curfain 

### has been added to an acoustic deterrent. However, there may be some hithertounexplored virtues of this combination. Firstly, bubble curtains absorb low frequency sound waves and therefore may offer 

### a means of containing the sound field to limit nuisance effects of extraneous sound, for example sound transmission through boat hulls in the vicinity. Similarly, any unwanted affects on 

### fish behaviour outside the immediate intake 

### area might be controllableby 

### this means. A second possibility is that 

### a bubble curtain, by limiting sound transmission, might be 

### used to manipulate the shape of a sound field to guide fish 

### in the most desirable direction, as 

### in the exampleshown

### in Figure 1. Theuse 

### of sound, rather than light, is therefore recommended to augment the bubble curtain as a fish deterrent at Heysham. 

### 2.3 Bubble 

### Curtains and 

### Augmenting Stimuli: Conclusions
0 

### For fish protection at water intakes, it is advantageousto angle the barrier relative to the flow, 

### so that fish are guided to a safe 

### area at one end of the barrier.
0 Bubblebarriers rely primarily on 

### a visual response by fish and 

### so are more effectivein daylight. Strobelight systems canbe used effectively to improve the over day and night, but 

### are likely to be impractical at Heysham due to frequent (weekly)inspection and maintenance requirements.
0 Underwater sound offers a more promising augmentary stimulus, with high system reliability and low maintenance costs for a well designed system. Combined with a bubble barrier, it should be possible to achieve high diversion efficiencieswith well-controlled sound distribution.

6

### - 3 DESIGN SPECIFICATION

### FOR THE HEYSHAM OUTER 

### BARRIER 3.1 

### Barrier Line The chief requirements for the outer barrier line 

### are: 1 that water velocity on the vector perpendicular to the barrier (see Figure 1) should be low enough for fish to 

### escape; 2 that the fish canbe guided by the barrier to a place of relative safety; 3 that the barrier should not interfere with harbour activities. Thefirsttwo 

### ofthese requirementscanbemetby selection of the appropriatebarrier line. Figure A1 and Table AI 

### of Appendix 

### 1give the flow direction and velocity 

### dataprovidedby Heysham

### 2 Power Station. In Table 1,thevelocityvalues of Table A1 (shown in ft 

### s-') have been converted to cm 

### s-'. The mean velocity across the points shownas 

### 1.1 to 

### 1.6 (FigureAl) 

### is calculatedtobe 

### 16.2cm 

### s-l. Table2 gives maximum approachvelocitiesthat will allow fish 

### of differentspecies and ageclasses to escape, based on swimmingperformance criteria (Turnpenny, 

### 1988). Previous investigations 

### of seasonal fish catch 

### (see Section 

### 4) have shown that the months of highest fish catch are October and November. Hence, maximum importance 

### is attached 

### to meeting fish requirements during this period, when water temperatureis expected to be above 7.5"C (Figure 2). Referring to Table2, for most species, fish of all age groups should be capable of escape at or above this temperature. Those which might not swim fast enough to escape are shown 

### in bold typeface (0-group pout, plaice, dab and sole). At lower temperatures 

### (see 2.5"C column of Table 2), more species would be susceptible to capture, though only 

### as the 0-group age class (i.e. less than one year old fish). To improve the chance of fish escaping from the intake currents, the barrier line should be slantedrelativeto the flow direction to achievetheeffect shown in Figure 

### 1(e.g. line lo>) rather 

### than 1 (a) in Figure A1 ). Fish detectingthebarrier 

### are then expectedto orientatethemselvesperpendicularto thebarrier 

### line, rather than parallel to the 

### flow streamlines, swimmingin 

### a direction away fromthebarrier. In this way, their movement has 

### a velocityvector parallel to the faceof the barrier 

### (UJ, as well 

### as oneperpendicularto andaway fromthebarrierline. Theminimumfish swimming speed required to maintain a constant distance ahead of the barrier 

### is 

### U,. For an angle 01 relative to the flow streamlines 

### (seeFigure l), the two velocity vectors 

### are given by:



### - and u3 

### U,.sin 01 

### (2) For the barrier line 

### l(b), a = 12", hence 

### U2 = 

### 15.8 cm s-' and 

### U, = 

### 3.4 

### crn s-'. With 

### this arrangement, the fish would tend to move 

### along the face 

### of the barrier 

### in 

### a north-easterly direction,passing furtherintotheharbour. Thebarrierlengthon

### this line is 

### 591x1, hence the maximum time to traverse the barrier would be of the order 

### of 28 min. As the fish escape velocities 

### are based on swimming speeds which can be sustained for at least one hour (Turnpenny, 1988), 

### this should present 

### no

7difficulties for those species for which figures are not shown

### in bold 

### type in Table 

### 1. Larger fish which are strong swimmerswilltend to swim parallel to the face of the screen and traverse it much more rapidly. 

### In the example of line l(b), the angle of 

### the barrier gives 

### a minimum swimming velocity required to avoid penetrating the barrier of 

### U2 = 15.8 

### cm s-l, only slightly lower than the flow velocity. For angles of a 

### > 12, the required escape velocity becomes progressively lower, 

### as shown in Table 

### 3. In order to achieve a velocity enabling 

### all fish to escape at water temperatures 2 7.5"C, a 60" barrier angle would be required, but this would more than double the required barrier length, to 134m. Even this barrier line would not enable 

### all fish to escape at lower water temperatures. As it would result 

### in at 

### least a doubling of cost for a smallbenefit, such an extendedbarrier would not in our view be worthwhile. To achieve optimum results, it would be advisable avoid contact of the barrier 

### lie with the dolphin structures located in the water inlet, as these will introduce breaks in the bubble curtain integrity. It is not essential for the barrier line to be straight and we would recommend a curved line, as shown in Figure 

### 3. The length of this line would be approximately 

### 75m. 3.2 

### Bubble CurtainParameters Hole Size and Spacing Design details for the bubble 

### curtain are taken 

### mainly from Copland (1977), who tested a range of designparameters. Thosegiven here were found to most effective for a bubble barrier operating in the 

### sea at 10mdepth. Holes in the 

### air tube should be 0.38mm diameter. Hole separation (pitch) should be 50 mm. The pitch of 16.5 cm indicated on the drawing supplied to us (Figure Al) is considered to be excessive for fish exclusion purposes. Hole spacing for a bubble curtain is analogous to the mesh 

### size of a fish net (Stewart, 1982), hence the 

### need for a closer hole spacing. 

### Tube Diameter and 

### Air Supply A tube internaldiameterof 50mm

### is recommended for the 75mbubblecurtain length, 

### to ensure an even 

### air distribution. The air compressor should be set to cut in at 

### a pressure of 

# -275kPa, and to cut out at 

# -420 Wa. With the hole size and spacing given above, the air supplyrequirement at this pressure 

### is approximately 0.02m3min-l per metre 

### of barrier. Thus for 

### the proposed 75m line, an 

### air supply of 1.5m3min-l willbe required. Efficientplumbing of the air supply is essential if energy losses are to be avoided. Sharp bends should be avoided, swept bends being used in preference. Abrupt changes 

### in pipe diameter should also be avoided. 

### Materials The pipeline and fittings should be manufactured of materials resistant to corrosion in 

### sea water. Semi-rigid alkathene or PVC plastic, of the 

### type used for domestic underground water supply, is suitable for the bubble 

### curtain tube. Care should be 

### taken to avoid using plastics which deform when heated for connection to the compressor as these may collapse and restrict the 

### air 

### flow. The supply from the

8compressorto the bubble 

### curtain should be of larger diameter than the bubble tube 

### itself to reduce frictional losses. 

### An internal 

### diameter of at least 

### 50mm is recommended. Kink-proofreinforced 

### PVC tubing would be suitable. The diameter shouldbe stepped down 

### in two or more stages to avoid abrupt changes 

### of diameter. Weighting 

### Down the Tube If plastic tube 

### is used, it will need to be weighted down to hold it 

### in place 

### on the 

### seabed. Arobust way to do 

### this is to bed the tube into 

### a steelU-section channel laid onto the seabed. Cross members (e.g. 

### 0.5 m lengths) attached 

### at intervals, perpendicular to the tube 

### axis, help 

### to stabilisethe assembly toprevent rolling of the 

### channel. The tube 

### is attached by means 

### of strong plastic cable ties. Itisunderstood, however, that forthe Heyshaminstallation, it mustbe readily liftable 

### for dredging operations. Attachmentto a steel chain may be suitablefor 

### this purpose. It is possible that the upward orientation 

### of the holes may be difficult to maintainby this method. This should not seriously affect the barrier, unless the holes become blocked by sediment. 

### Provision 

### for Purging 

### the 

### Lime If the barrier 

### is switched off for any reason, it is likely that water and silt will enter the 

### air-line, which will be difficult to purge via the normal 

### air outlet holes. Apurge valve should therefore be fitted. For this purpose, it will be necessary to bring 

### the end of the air-line opposite 

### to that attached to the compressor out of the water, and 

### to terminate it with a valve, e.g a gate valve. On starting up the system, the valve should be opened to 

### allow compressed air to purge water 

### from the line, then closed. 3.3 

### Addition of 

### Underwater Sound Signals Modulation of the Air 

### Supply Our original suggestion for a low cost option 

### of providing an additional sound stimulus to the barrier by modulating the 

### air supply 

### has not been tested and would require 

### trials at 

### our Fawley laboratories to determine the feasibility of the approach. Such trials would 

### need to be undertaken during the summer of 

### 1992in order to be ready for autumn field 

### trials. The basic idea would be to utilise 

### an electromagnetic solenoidvalve to pulse 

### the 

### airflow in sucha way that the noise was transmitted 

### along the entire length of the bubble barrier. 

### The following questions would need 

### to be investigated: i) Can signals produced 

### in this way be 

### used to deter 

### fish? ii) 

### Are they effective 

### on the target species? 

### iii) 

### Can adequate sound pressures be generated to exceed ambientnoise levels 

### in Heysham Harbour? iv) Will modulating the 

### air supply 

### in this way detract from bubble propagation? v) Will the sound generating equipmentoperate reliably in continuous service? The advantages 

### of this approach, if it worked, would be low capital cost and low installation and maintenance cost. Essentially, it would add to the basic bubble curtain hardware only 

### an electromagnetic modulator valve and a simple electronic
9driver system. 

### Electromagnetic Transducers An alternative to 

### this approach would be to place an array of electromagnetic transducers in the water, behind 

### (i.e. downstream of) the bubble 

### curtain. These would best be deployed from a floating boom located parallel to, and 

### from a few metres downstream 

### of the barrier line. The transducers would 

### be suspended midwater, with supply cables feeding back to a dock 

### wall control centre containing the signal generator, amplifier and filter system (see Thatcher and Irving, 1992). 

### This would take advantage of 

### an acoustic deterrent signal developmentprogramme being sponsored corporately for 1992by Nuclear Electric (contact: 

### Mr CJ 

### LTaylor, Barnwood, Location 106), 

### in which signals suitable for fish deterrence are 

### to be identified. A survey of the intake area would be required to determine the number of transducers necessary to produce a uniform sound field across the barrier and to establish ambient background sound spectra. 3.4 Bubble 

### Barrier Design 

### Parameters: Recommendations The recommendeddesign parameters for the bubble barrier are as follows:
0
0
0
0
0
0
0
0
0
a
0

0 barrier 

### line: curved, 

### as shown in Figure 3 barrier length..


## ..................... .75m bubble tube internal diameter


## .........50mm bubble outlet hole size


## ............... 0.38mm hole pitch


## ............................ 50mm operating pressure.. 

## .................. 276kPa (switch-on), 414Wa (switch-off) 

### air demand


## ............................ 1.5m3min-' bubble tube material: semi rigid PVC or alkathene delivery tube material: spirally-reinforced PVC hose seabed attachment: steel 

### chain and cable ties bubble tube purging: via a gate valve attached to the end away from the compressor, out of the water augmentary stimuli: acoustic, by low frequency 

### (<1OOHz) modulationof 

### the air supply, orusing 

### an array of electromagnetictransducers behind thebubble barrier, fed from 

### an onshore signal generator/ampMer system.

10

### 4 STATISTICAL

### DESIGN

### FOR SAMPLING AT HEYSHAM 

### 4.1 

### Statement of Problem To determine whether the proposed bubble barrier 

### in front of Heysham 

### 2 Nuclear Power 

### Station will reduce the number of fish captured on the intake screens. Additional fsh deterrent methods might 

### also be operational, the efficiency 

### of the different components of the fish deterrent system will not be individually identified. 4.2 

### The Hypothesis For both the total fish catch and individual 

### species the null hypothesis is that the bubble screen produces no significant reduction in the catch 

### of fish 

### on the screens. 4.3 

### Sampling Technique Fish 

### and debris washed from the 

### four Heysham 

### 2 drum screens 

### will be intercepted, probably using baskets placed in the screen washing channels running from the individual 

### screens. Thefish catch will be 

### sorted to species and the number and weight 

### of individual species caught per unit time recorded. Samples 

### of fish will 

### also be measured (standard length) to show the sizes and approximate ages of fish caught. To determinewhether the bubble screen reduces the fish catch the 

### rate of capture 

### offish willbe determined with the bubble screen both 

### on and 

### off. 4.4 Key 

### Species It 

### is important to ensure that the experimental design 

### is capable of assessing the fish deterrent capability 

### of the bubble screen for key 

### species. Key species are defied 

### either by their high abundance 

### in the area, conservation value 

### or importance to fishermen. Examination 

### ofthe screen catch data and 

### has identified the following 

### as key species:

Bass Dicentrarchus labrax

- occasionally caught sport fish Silver eel Anmilla anguilla


### - abundant October and February Sand goby Pomatoschistus minutus


### - abundant November Herring Clupea harenrrus 

## - abundantNovember to February HooknoseAponus cataFhractus


### - abundant November Poor cod Trisopterus minutus 

## - abundant Octoberto January Pout Trisopterus luscus


### - abundant November 

### to January Sprat Smattus 

### sprattus 

## - abundant November to January Whiting Merlangius merlanpus


### - abundant Septemberto December. Brown shrimp CranEon crangon 

### - abundant October to January

11

### 4.5 Xxperimental

### Design Time of 

### Year As shown 

### in Figure 4 the annual pattern of fish capture at Heysham 

### is highly seasonal. More than 

### 90% of the total 

### annual catch by either weight or number 

### of individuals occurs between October and April and the maximum

### rate of capture has been observed to occur 

### in the months of October and November. An examinationof the seasonal pattern of occurrence of the key species indicates that this sampling period coincides with the periods of maximum abundance

### of all the key species with 

### the possible exception of bass. In the case of bass, the recorded rates of capture are too low to reach a conclusionon seasonality. However, information from other sites indicates that bass capture rates are usually greatest in the autumn. 

### Tidal Factors As shown

### in Figure 5 the rate of fish captureis inversely related to tidal height. Thus it is important that the sampling strategy ensures that samples are collected over the low water period when most of the fish arrive. Further, the sampling design 

### must ensure that fish capture rates for periods with and without the bubble screen are controlled for 

### tidalheight. It is proposed that a standard six hour samplingperiod be employed

### with low water at approximately at the end 

### of the third hour of sampling. This strategy will 

### maxirnise the number of individuals vulnerable to capture while minimising the sampling effort. Diurnal 

### Factors Little is known aboutdiurnalpatterns 

### of capture. Whileat somepower station intakes the 

### rate of fish capture is greaterin the dark

### this is unlikely tobe a significantfeature at Heysham. This isbecause of the on-shore position of the intakes; in power stations with this 

### type of configuration tidal factors tend to dominate short-term temporal variation. 

### Itisrecommendedthat 

### day lengthbe addedto the data set 

### so that any trend attributableto this variable can be removed from the data. 

### Fish Storage A factor which will tend 

### to reduce the distinction between fish catches with the deterrent systems off or on 

### is the presence of fish between the barrier and the intake screens which have entered during the preceding period. This storage effect 

### can be minimised by the following measures. Firstly, fishpresent in the screenwells 

### canbepurged fromthe systemby chlorinating the screenwells fora period 

### of 

### 2-3 hours immediatelyprior to 

### each trialperiod. The required chlorine concentration is of 

### the order O.5ppm applied dose. Sodium hypochlorite 

### is suitable for this purpose, 

### if normal station chlorination has been suspended. The second measure is to switch on 

### the deterrent system, not at the beginning of the 6 hour test period, but at the end of the preceding control period.

12

### Screen

### Bias It has been noted previously that fish capture 

### rates tend to increase 

### from screen 8d to 

### 7b.This is probably related to the orientation of fish 

### in relation to the breakwater wall. It is proposed that the samples 

### from all four screens are bulked for each sampling period to remove screen bias. This recommendation assumes that 

### all 4 pumps will be operating during the experimental period. If this is not 

### the 

### case care must be taken to ensure that the same screens are sampled during the periods when the bubble screen is on and off. 

### UncontrolledFactors Weather conditions such 

### as wind, 

### rain or changes in the flow 

### of local rivers may effect

### localfish abundance. 

### A weather record and the salinity and temperature of the extracted water shouldbe recorded for 

### each sampling period. While it 

### is likely that uncontrolled factors 

### will be assumed to contributeto the error-term in the analysis of variance, it might become necessary to exclude some samples if they were to be collected during unusual weather conditions. This would be 

### the case if periods with comparableenvironmental conditions were not sampled with the bubble screen 

### both on and 

### off. Temporal Arrangement of Sampling 

### Periods To avoid bias linked to uncontrolled factors, and the change 

### in tidal range linked to the spring-neap cycle the following arrangement of sampling periods is proposed. A single samplingperiod ( of six hours duration) will be undertaken each day to cover the low water period for which the majority or 

### all of the period 

### is during daylight. The entire experiment should be undertaken 

### on consecutive days with the bubble screen operating every other day. This scheme

### is summarisedin the following table.
Bubble screen on Day 

### 1: Samplingperiod 1 Day 

### 3: Samplingperiod 3 

# I1 *

# -- ' *-- * * 

# 11 Day 

### n-1: sampling period 

### n-1 Bubble screen off Day 2: Samplingperiod 

### 2 Day 

### 4: Samplingperiod 

### 4



## .......... I 

# 1 Day n: Samplingperiod 

### n
EstimatedNumber 

### of Sampling Periods Given a balanced experimental design as described 

### in 4.5 the effect of the bubble screen can be assessed statistically using a standard t-test to compare the means of fish caught with and without the bubble screen.

13When sample sizes 

### are equal and the null hypothesisis that the means 

### are the same (Section4.2),

where

### XI is the mean number caught

### per period with the bubble screen working 

### X2 is the mean number caught per period without the bubble screen 

### varl is the variance of the catch with the bubble screen working 

### var2 is the variance of the catch withoutthe bubble screen and 

### n is the total number of samplingperiods. The number of sampling 

### periods required for the experiment depends on the significancelevel chosen, the degree of differencebetween the means we 

### require to detectand thevariancein therate of capturebetweenperiods. It 

### also depends on the effort we 

### are able to expend, but we shall assume for the present that 

### this is not limiting. The least significant difference, 

### LSD, is the least differencebetween two means for whichit wouldbe concludedthat they were significantlydifferent. For the proposed experiment

### a significancelevel of 

### 5%is appropriate

### so the LSD is defined 

### as
LSD 

# - tmOs [n]r(l/n(varl +var2))
Thus given an estimateof the variances we can estimate the LSD for different It. During October 

### 1985three consecutive24hr samples werecollectedfrom the screens of Heysham 

### 1. Assuming that half of the observed daily catch would have been caught 

### in a 

### six hour sampling 

### period centred on iow water, this suggests that the mean and varianceof ourproposed sampling schemewouldhavebeen 480 and 

### 4938 respectively. Similarcalculations for three samples taken in November 1985give an estimated mean and variance of 

### 176 and 

### 5001respectively. Thesecalculations suggestthat without

### a bubble screen operatingitwouldbeprudent to assume 

### a mean catch of 

### 300 fish per period with a variance of 

### 5000. We it 

### is likely that the variance 

### in the number of fish captured when the bubble screen is 

### operational will be lower, at the planning stage it 

### is prudent to assume 

### a similar variance.

14Number of sampling periods 

### n

4 8 12 16 20 32 

### t for 

### n samplingperiods 

### LSD and 

### 5% significance level 2.13 106.5 1.86 65.8 1.78 51.4 1.75 43.8 1.72 38.5 1.7 30.1

From this table it 

### can be seen that to detect a 10% reduction in catch due to the bubble screen, given a mean catch rate of 300 per period, would require sampling over 

### a 32 periods (days) of sampling. 

### Inpractice, a 20% reduction or more would be environmentallyimportant (difference between the means of 

### 60) and this could be detected with reasonable certainty with 12 samplingperiods ( 12 

### days). The 

### same general conclusionsforthe numberof samplesalso applies to the individual key species. 4.6 Recording 

### Proformas Appendix 2 contains samplerecording proformas. One set of sheets should be 

### used for each six-hour sampling session. The first sheet accommodates a range environmental and operational parameters which will assist 

### in interpretation of the 

### trials, together with the total hourly catch figures. The second sheet accommodates data 

### on fish size 

### so that the approximate age classes 

### of the catch 

### canbe determined. These proformas 

### are also available as 

### Lotus 1-2-3 spreadsheets. 4.7 Experimental 

### Design and Statistics: Recommendations Thebubble 

### curtain experiment should be undertaken over a minimumtwelve 

### day period 

### in the months of October or November. Tidal and operational conditions permitting, the best period would be the last week of October and the first week of November. 

### Once sampliig has commenced it should be undertaken 

### on consecutive days. This will require week-end work. It 

### is recommendedthat 

### two working days be assigned at the beginning of the experimentalperiod during which the samplingequipment 

### willbe 

### installedand working methods defined. It is recommended that chlorination of the screenwells at 

### an applied dose of



### 15OSppm should be undertaken for a 

### period of 

### 2-3 hours prior to each trial period, to minimisethe adverseeffectsof fish storageon interpretationof the testresults. Sodiumhypochloritedosingwouldbeadequatefor

### this, ifnormal station chlorinationhas been suspended.
0 

### To add 

### an augmentary sound stimulus, 

### a second, similar period 

### of testing would be required, in which the sound system and the bu6ble curtain were operatedsimultaneously, againwithalternatingdaysofoperation. Thiswould be necessary to ensure that one

### or other system was not redundant. Ideally, a third twelve day period wouldbe

### used to operate the sound system without thebubblebarrier, unless it were already decided that 

### abubblebarrier would be operated there for other reasons.
0 Any 

### trials using 

### a sound system would require 

### an initial survey and a minimum of 

### two weeks prior to the trials for installation and testing. A temporary system could be installed for the period of the trials 

### only, using 

### FAWLEY 

### arl Ltd’s mobile 

### fish deterrent caravan.
0 Thereis

### no requirementfor theinnerbarriers (shown as

### 2 & 3 onFigureAI) to be installed or operational during trials with the outer barrier. It 

### is, however, important that operating conditions should be maintained in a constant state during the trials, 

### so that if they operational, then they are always operational 

### or vice 

### versa.

16

### References Blaxter, J.H.S and Parrish, B.B. 

### (1965). The reactions 

### of marine fishes to 

### moving netting

and other objects 

### in 

### tanks. Mar. Res., 1960/61. CEGB 

### (1961). Preventing 

### theentry of salmon smolton migration


### - survey ofresearch 

### 1956­



### 61. Central Electricity GeneratingBoard, 

### SouthWales Division. Operational Report 

### No. 77. Copland, P.J. 

### (1977). Design, developmentand fieldtesting of abubble curtain. Department



### of Agriculture and Fisheries for Scotland, Working Paper No. 

### 77/14, 10pp. Hawkins, A.D. 

### (1973). ’The sensitivity 

### offish to sounds’. 

### Oceanogr. 

### mar. Biol.Ann.

### Rev.



### 11, pp. 

### 291-340. Lieberman, 

### J.L. and Muessig, P.H. 

### (1978). Evaluation of 

### an air bubbler to mitigate fish

impingementat an electric generating plant. 

### Estuaries 

### 1 (2), pp.129-132. Loeffelman, P.H., 

### Klinect, D.A. and Van Hassell, 

### J.H. (1991). Fish protection at water

intakes using 

### a new signal development process and sound 

### system. Published 

### in “Waterpower

### ’91”,

### Proc. 

### Int. Con$ 

### Hydropower,Amer. SOC.

### Civ. Engrs., pp. 

### 355-365. Matousek, J.A., Wells, 

### A.W. and McGroddy, P.M. 

### (1988). Field testing of behaviourial

barriers for fish exclusion at cooling water intake systems. WRI Report No. 

### CS-5995, Electric Power Research Institute, Palo Alto, Ca. USA. Milne, P.H. 

### (1970. 

### Air bubble curtains and their use 

### in coastal waters. 

### Fluid Power



### International May 

### 1970, pp. 

### 33-36. Mishchenko,

### V.S. andPestryakov, V.N. 

### (1986). Problemofprotecting fishat water intakes.



### Gidrotechhnicheskoe Stroitel’stvo 8, pp. 

### 50-52. Patrick, P.H. 

### ,Christie, A.E. 

## ,Sager, D. 

### ,Howett, C. and Stauffer, J. 

## ,Jr. 

### (1985). Responses

of fish to 

### a strobe light/airbubble barrier. 

### Fish. Res. 3,pp. 

### 157-172. Patrick, P.H., McKinley, R.S and Micheletti, 

### W.C. (1988). Field testing of behaviourial

barriers for cooling water intake structure 

## - Test 

### Site


### - Pickering Nuclear Generating Station. In: ’Proceedings: Fish Protection at Steam and Hydroelectric Power Plants: Electric Power Research Institute’ 

## , EPRI C8IEAIAP-5663-SRpp.4.13-4.25. Smith, 

### K.A. (1961). Air curtain fishing forMaine sardines. 

### US Dept. 

### of the Interior, Fish

and Wildl. Serv. 

### CommercialFish. 

### Rev. 23 (3), pp. 

### 1-14. Sonnichsen, J.C.,Jr, Bentley,B.W., Bailey,G.F. 

### and Nakatani, R.E. (1973). A 

### review of

thermal power plant intake structure designs and related environmental considerations. Hanford Engineering Development Laboratory, Richland, Washington, Rpt. No. HEDL

### TME-73-24. Distributed by National Technical Information 

### Service, US Dept. of Commerce, 

### 5285, 

### Port Royal Road, Springfield, 

### Va 22151, USA. Stewart, P.A.M. 

### (1982). 

### An investigation 

### intothe reactions 

### offish toelectrifledbarriers and

bubble curtains. 

### Fish. Res. 

### I, pp. 

### 3-22. Thatcher, K.P. and fig, P.W. 

### (1992). Fish deterrent 

### trials at Oldbury Power Station. NationalPower/Nuclear

### Electric Common

### MarineProgramme,Research

### Report (inPress).



### 17

### Turnpenny, 

### A.W.H. 

### (1988). The behaviourid 

### basis of 

### fish exclusion 

### from coastal power station cooling 

### water intakes. CEGB 

### RD/L/3301/R88. Central Electricity Generating Board, London.

18

### Table 1 

### Flow Velocities 

### Measured &toss 

### Points 1.1 

### to 1.6 

### (cm s") (Figure

### Al, Appendix 1)



### Position Depth 

### (in) 1.1 

### 1.2 1.3 1.4 1.5 1.6 

### 0 14.9 

### 20.7 9.1 10.1 10.1 9.1 1.8 20.7 

### 16.5 

### 18.3 

### 20.8 16.5 

### 3.7 16.5 15.0 

### 20.8 16.5 9.1 5.5 20.7 

### 16.5 16.5 7.3 

### 24.9



### Mean velocity = 

### 16.2 

### cm 

### s*' Standard

### error 

### = 4.7 

### cm 

### s-'

### Table 

### 2 

### Maximum Approach Velocities 

### Which 

### Will Enable 

### Fish to Escape at Different Water Temperatures (Tmmpenny, 

### 1988). 

# I1

Temp 

### "C

SDecies sprat Herring Cod whiting Pout Poor cod Plaice Flounder Dab Sole Bass Grey Mullets Sand Smelt



### Salmon Smolts 

# I Age Group 0 

### and Older 

# 1 Min. 

# I Age Group 1 and 

### Older Length 

# 1
n.5 17.5 Age 1

cm s-' 

## - cm s-' 

### cm 30 40 50 

### 60 8 50 

### 64 78 92 30 40 50 

### 60 12 50 65 80 94 

### 15 30 40 

### 55 15 30 52 74 95 

### 10 25 40 50 15 35 

### 55 79 102 

### 8 15 20 29 20 34 60 83 105 10 25 35 50 10 26 40 59 73 8 

### 15 20 30 8 28 48 

# I 67 92 

### 10 20 30 40 12 28 46 66 86 2 

### 10 20 26 10 12 23 34 46 5 

### 15 20 30 11 22 40 57 72 20 35 50 66 9 37 59 83 109 20 35 50 60 10 30 50 69 89 

### 10 20 130 40 

### 7 24 40 53 70

Age Group 

### 1 and Older Age Group 2 and Older 80 15 

### 55 68 79 91



### Min Autumn temp. -7.5"C

ONational 

### Power 1988

22

### Table 3 

### Escape Velocities �orVarious Barrier 

### Angles �or 

### a Flow Velocity 

### of 

### 16.2cm s-', 

### and ApproximateBarrier 

### Lengths

Angle (a) 

### Escape Velocity 

### (cm

### 6) Barrier Lengths 

### (m) 12 15.8 59 20 15.2 65 30 14.0 74 40 1 12.4 87 50 10.4 110 60 

### 8.1 134 1

# 7

/ f I I I I I / / / / (d 

# fn U 

## c cif

n 

## cu 3 U
(d 0 

# 3

a, Y aj +-' t 

### -

I / I I / I I / I I

. ..1'
I(

l! DEEP SLA AMBIENT FROM MET. OFFICE 11 FOR THE SURV�Y PERIOD

1:

1:

I1

0 14 0 w CL: 3 4 t 6 U 

### ws I 

### a I w AVERAGE TJZMPERATURE 

# !-' AT HCYSHAW MONTHLY MEANS 6 1906- 1954

6

4

3

2

t

0 a I I 4 a s s a I I J F' 

### H A 

### M' J J A S O N 0 WONTHS 

### Figure 2 

### AnnuaI 

### Cycle of 

## Sea Temperature at 

### Reysham (unpublished report by Parker, GCC and Lovejoy,�!., dated 11.1.80: held in the Nuclear Electric Archive, FAWLEY arlLtd)c 

# f

cr, 

### .­

0 0 0 0 0 0 0 0 0 0 m 0 

## - tn mi F 'r

# FIGURE 5 

# Tidal Fish Catch Patterns Heysham2 

## Power Station 

## (Screen 7b) 

## November 1989

.........................................................................................

.......................



# t-lw

..........................................................................................

.....................



## _............................................................................................................................ 

### &W

...................

. 

### Clupeids 29.11.89

- 1.m ................. ........................................................................................................................

......................... L............... _

6M)

## _ ......................... <
............................................

400 -......................... i...................................

2(n _. ....................... 4
..................................
Od I I I I I I I I



### Time GMT Surveys undertakenby Fawley Marine Biology Unit Copyright 1992 National Power

### APPENDIX 

### 1

Data 

### onPromxed 

### General Arrangement of 

### the Triple Barrier 

### and Current Velocity 

### and Direction Data
as 

### sumlied bv 

### Hevsham 2 Power Station

# -+E­



# \. . . , .- __ ­

..

!

i 

## 1

:: i i

i

# i I 

# ! i i

i i

1 

# i

I 4

, , ii! 

## i ! 

## 1 

# iY

### APPENDIX 2

Sample Recording.Proformas for Fish Barrier Trials at Heysham

# FAWLEY aquatic 

# research laboratories Ltd
HEYSHAMFISHDETERRENT

# SYSTEM TRML 

# S

Data Recording Proforma Fish Lengths 

### Date Sample Time Sheet-] of

r Species Length(mm) Species 

### Length(mm)

I 

# I

## FAWLEY aquatic research laboratories Ltd



## HEYSWAM 

# FISH DETERRENTSYSTEM TRIALS

Data Recording Proforma
Date 

## 1-1 StaffNames 

### I 

## I

Start Time 

## U Finish Tlme 

## 1-1 Hours ofDaylight 

## 7 1 (during sampling)
Off On Bubble Curtain

PhysicalMeasurements
Water Temperature (C) 

## 1 1 Turbidity (SDextinction, m) Salinity (ppt) 

# -

TidalState 

## 17 HWTime 

## 1-1 LW Time 

## 1-1 HW Ht(m) 

## { I LW Ht(m)
CWPumps Running (tick for 'on') Sta e One Sta eTwo 

# -1 -1