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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
4
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
5
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
6
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
9
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
10
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?