ELECTRICAL TRAWLING FOR BROWN SHRIMP:
IMPACT ON YOUNG LIFE STAGES
IN NURSERIES & SPAWNING
Desender Marieke , Chiers Koen , Verschueren Bart , Polet
AREAS Hans , Duchateau Luc , Velmurugu Puvanendran ,
1,2
2
3
4
INTRODUCTION
Catching shrimp without touching the
seafloor by electrical stimulation results in:
2
5
• Discard reduction 65%
• Less bottom contact 80%
• No immediate effects on
adult fish!
Mortensen Atle5, Decostere Annemie1
1
Department of Morphology, Faculty of Veterinary Medicine, Ghent University,
Salisburylaan 133, 9820 Merelbeke, Belgium
2 Institute for Agricultural and Fisheries Research (ILVO), Animal Sciences – Fisheries,
Ankerstraat 1, 8400 Oostende, Belgium
3 Department of Pathology, Bacteriology & Poultry Diseases, Faculty of Veterinary
Medicine , Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
4 Department of Comparative physiology and biometrics, Faculty of Veterinary
Medicine, Ghent University, Salisburylaan 133 , 9820 Merelbeke, Belgium
5 The Norwegian Institute of Food, Fisheries and Aquaculture Research
(NOFIMA), Muninbakken 9-13, 9291 Tromsø, Norway
Impact on younger life stages?
5-10
10-15
15-25
25-50
50-100
100-200
>200 V/m
70cm
Simulation electrical field
RESULTS
EMBRYONATED EGG STAGES
Exposed
# Viable eggs/50ml
Control
# Viable eggs/ 50ml
Survival Stage
Survival Stage
60
50
40
30
20
10
0
0
5
60
50
40
30
20
10
0
0
60
50
40
30
20
10
0
5
15
20
25
Survival Stage
0
10
10
5
10
15
20
• No significant difference
in survival over all egg stages
• No significant difference in
Hatching rate between control
and exposed groups
25
Day 0
Fertilisation
1DPF*
Early cleavage
100
90
80
70
60
50
40
30
20
10
0
6
7
8
Developmental stage
5DPF
Epiboly
THE EXOGENOUS LARVAL STAGE
Morphological analysis:
Differences in yolk resorption,
length, growth, …
Deformations
Development
germ layers
Heart is beating, eyes
are pigmented
500µm
1000µm
After 4 Years
Adult
Feeding on
rotifers but the
yolk is still
present
Juvenile
FUTURE RESEARCH
Sample during
further
development
↑Plate shaped Electrodes
creating a homogeneous
electrical field of 150V/m
↘Development of cod
*DPF=days post
fertilisation
**DPH=days post
hatching
60DPH
• Handling effect of stage
• Mortality is significantly higher
in the exogenous stage
(OR 1.94 p<0.0014)
• No difference in survival
between exposed and control
groups in the other larval
stages or the juvenile stage
Survival larvae & juvenile stages
Survival %
Expose for 5 seconds
to 150V/m
Count survival after
1 week
LARVAL & JUVENILE STAGES
5
Cod (Gadus morhua)
eggs, larvae and
juveniles
Days after exposure
Days after exposure
4
MATERIAL & METHODS
4000µm
1000µm
No yolk, need to
chase prey
2000µm
Development of 3
dorsal fins, digestive
system
2000µm
REPEAT THIS EXPERIMENT
ON SOLE (Solea solea)
A flatfish with a special
metamorphosis
1000µm
 marieke.desender@Ugent.be