Institute for Agricultural and Fisheries Research www.ilvo.vlaanderen.be

Agriculture and Fisheries Policy Area

Institute for Agricultural and Fisheries Research

SG Electra

Presentation PhD-research

Drs. Ir Maarten SoetaertUGhent - ILVO

2

Content

• ‘Safety Margin’ for a selection of marine species– Determine the injury dose (ID50)

– Determine the lethal dose (LD10)

• Optimalisation of startle pulse for sole– At ≠ frequency, field strength, waveform,

wavelength, pulse type

• Effect of startle pulse for sole on marine species

• Effect of electrical pulses on fish quality

3

Safety Margin (I): idea

• Goal: determine the injury dose (ID) and lethal dose (LD) for a selection of marine organisms:– Sole: target species

– Cod: top predator, sensitive to pulses

– Shrimp: target species

– Sandworm: model species for polychetes

• Starting from startle pulse for Crangon crangon

• At 50 & 100 V/m: 5 Hz → 180 Hz

invertebrate

vertebrate

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Safety Margin (II): What?

• Injury Dose x% (IDx): frequency at which x % of the exposed animals shows extra injuries

• Lethal Dose x% (LDx): frequency at which x % of the exposed animals dies

0 10 20 30 40 50 60 70 80 900%

25%

50%

75%

100%

Logistic Regression (example)

# with injuries# mortalities

Frequency (Hz)

In this example:ID25 = 25HzLD50 = 45 Hz

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Safety Margin (III): How?• Homogeneous Field

– Exposure (3s)

• 2 plate-shaped electrodes

• Orientation:

– Euthanasia after 14 days

– Autopsy

• Macroscopic: hemorrhages, color,

spots, deformation, …

• Rontgen photos (lateral & dorsal)

• Histology: dorsal muscle, kidney,

liver, spleen, intestine, gills, heart

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Safety Margin (IV): Why?

• What can we learn out of it?– Difference in sensitivity between 4 species

– Effect of field strength on effects (injury/mortality)

– Effect of frequency on effects (injury/mortality)

– Kind of injuries function of frequency?

– Is there a ‘safe’ range of pulse parameters in which we can apply pulses in justifiable way?

– Pulses of Hovercran/Pulskor/Pulswing in safe zone?

7

Content

• ‘Safe Zone’ for a selection of marine species– Determine the injury dose (ID50)

– Determine the lethal dose (LD50)

• Optimalisation of startle pulse for sole– At ≠ frequencies, field strengths, waveforms,

wavelengths, pulse types

• Effect of startle pulse for sole on marine species

• Effect of electrical pulses on fish quality

8

Startle Pulse for Sole: idea

• 25 % of sole jumps out of sediment during exposure

to startle pulse for shrimp (Chiers et al., 2011)

Is there a ‘safe’ startle pulse that makes the majority

of the sole jump out of the sediment ?

• Varying different parameters: frequency, field

strength, pulse form, pulse duration, pulse type

Chiers et al., 2011, ‘Short-term effects of low frequency pulsed direct current on captive-housed sea fish’, submitted

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Startle Pulse for Sole: parameters

• Frequency:

• Field strength:

• Pulse form:

• Pulse duration: 0,1 to 0,5 ms

• Pulse type:

• Time of exposure: 1 to 2 s

Within Safety Margins

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Startle Pulse for Sole: how?

• Video tracking of reaction during exposure at specific pulse, quantification & comparison

Parameter Effect score (A)Weight (B) Total (T)

3 2 1 = A x B

1. Hight upbove bottom (cm) > 15 5 - 15 < 5 3 T1

2. Swimming speed (% of max) < 75 25 - 50 < 25 1 T2

3. Recovery time(s) > 3 3 - 1 < 1 2 T3

TOTAL “EFFECT NUMBER” (= assesment number of observed startle response) T1 + T2 + T3

11

Content

• ‘Safe Zone’ for a selection of marine species– Determine the injury dose (ID50)

– Determine the lethal dose (LD50)

• Optimalisation of startle pulse for sole– At ≠ frequency, field strength, waveform,

wavelength, pulse type

• Effect of startle pulse for sole on marine species

• Effect of electrical pulses on fish quality

12

Startle Pulse for Sole: Effects

• Video tracking of reaction after exposure at optimal sole startle pulse– Feeding response

– Behavior

• Euthanasia & autopsy (cfr ID & LD):

– Macroscopic

– Rontgen photos

– Histology

sole & cod

sole & codshrimp & sandworm

13

Content

• ‘Safe Zone’ for a selection of marine species– Determine the injury dose (ID50)

– Determine the lethal dose (LD50)

• Optimalisation of startle pulse for sole– At ≠ frequency, field strength, waveform,

wavelength, pulse type

• Effect of startle pulse for sole on marine species

• Effect of pulses on fish quality

14

Effect of pulses on fish quality

• Is there an effect on the sole quality?≠ in appearance?

• Pulse fisherman is getting a better price: why?

• What/how big is the difference with beam trawl?

≠ in filet quality?

• Do electric pulses have an effect on fish decay?

(QIM)

f.e. faster or slower decay

≠ in filet taste?

Institute for Agricultural and Fisheries Research www.ilvo.vlaanderen.be

Agriculture and Fisheries Policy Area

Institute for Agricultural and Fisheries Research

Thanks for your attention!Questions?