electric pulse fishing what do we know and what is the research agenda? 17-11-2014, a.d. rijnsdorp...
TRANSCRIPT
Electric pulse fishing
What do we know and what is the research agenda?
17-11-2014, A.D. Rijnsdorp & M.M.M. Rasenberg
Introduction
Background
Beam trawl fishery for flatfish (sole & plaice)
●Tickler chain impact on sea bed and benthos
●Small mesh large bycatch of undersized fish
●High fuel cost (heavy gear and high towing speed)
Pulse trawl
●Since 2009 based on temporary licences
●Indications of an increase of sole catches & decrease bycatch (fish and benthos)
●Reduction in fuel costs: about 50% (lighter gear and lower towing speed)
Regulation
1988 2001 2011 20142007
No. of pulse trawlers in the Netherlands
1-Ja
n-09
1-Ju
l-09
1-Ja
n-10
1-Ju
l-10
1-Ja
n-11
1-Ju
l-11
1-Ja
n-12
1-Ju
l-12
1-Ja
n-13
1-Ju
l-13
1-Ja
n-14
1-Ju
l-14
0
10
20
30
40
50
60
70
80
90N
um
ber
of
acti
ve v
essels
84 licences
Experimental phase
Targeting flatfish & shrimp
isolator
conductor
Electric field: non homogeneous
V/mV/m
V/m
Conductor
Isollator
Pulse parameters
Pulse type
●Delmeco
●HFK
Amplitude (V)
Frequency (Hz)
Pulse width (ms)
Current settings
40-80 Hz, 120 V
Amplitude(V)
Frequency (Hz)
Pulse width (µs)
DELMECO
HFK
Concerns
Possible adverse effect of electricity on marine organisms
●Mortality
●Injuries
●Ulcers
Increase in fishing efficiency and risk of over-exploitation
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
% V
oo
rko
men
Zweren op schar
Totaal letsels zweren
% dab with ulcers (Belgian coast)
(ILVO: Devriese, L., 2014)
No evidence that this is caused by the pulse technique
What do we know?
Conducted research
Research started in 1998 and focussed on:
●Catch efficiency & selectivity
●Catch composition
●Effect of electricity on marine organisms
●Ecosystem effects
Catch efficiency & selectivity
Comparative fishing experiment in 2011: TX36 (HFK), TX68 (Delmeco), GO4 (Tickler chain beam trawl)
Van Marlen et al. (2014) Fisheries Research
Catch efficiency
Tickler chain n=33
Pulse n=2*33
Ratio Puls
/tickler
Plaice (kg/hectare) 1.34 1.26 94%
Sole (kg/hectare) 0.59 0.61 103%
Landings(baskets / hectare) 0.10 0.08 81%
Discards (baskets / hectare) 0.59 0.25 43%
Van Marlen et al. 2014
Selectivity (plaice & sole):
lower by-catch undersized flatfish
Van Marlen et al. 2014
Schol
Tong
Catch per unit area sweptPulse / Tickler chain
1:1
Puls lower
Puls higher
Catch composition
Self-sampling & observer program
December 2011 - March 2013
25 pulse trawl vessels
Type of fishery
Plaice Sole
L DC %DC L DC %DC
Pulse self-sampling
37 27 42% 35 6 15%
Pulse observer
61 66 52% 32 4 10%
Beam trawl (DCF)
90 87 49% 29 6 17%
Rasenberg et al., 2013, IMARES report C122/13
Effects on marine organisms
Lab experiments (ILVO, University Gent, IMARES)
Exposure 2 sec
●Cod & Sole & Dogfish
●Brown shrimp & Nereis
Measurements
●Survival (2 weeks) & behaviour
●Macroscopic
●X-ray & Histology Uni Gent: Marieke Depestele; Maarten Soetaert; Annemie Decostere; ILVO: Hans Polet;IMARES: Dick de Haan; Bob van Marlen
Experiments:effects on COD
Wild cod
● 4% (1/25)
Aquaculture cod
● 0% (0/145)
● 2% (1/53)
●17% (5/29)
●48% (125/260) large cod
●0% (0/122) small cod
Results of the effect studies
Behavioural response Injuries Mortality FeedingCod Escape (<20 Hz)
Cramp (>20Hz)Epileptic (120V)
Fractures Haemorrhages
No Resume normal feeding
Sole Escape (<20 Hz) Cramp (>20Hz)
Epileptic (extreme)
None No Resume normal feeding
Dog-fish Escape None No Resume feeding; deposition viable
eggsShrimp Jump (<20 Hz)
Cramp (>20Hz)None No -
Nereis movement None No -
Depestele et al (in prep); Soetaert et al (2014) ICES JMS; De Haan et al. (in prep)
Effects on dab: experiment to study ulcers
Three groups of 50 dab
Maximal exposure
●DELMECO (60V)
●HFK (70V)
●Reference group (not exposed)
After 1 week killed and examined for lesions, ulcers, wounds, parasites
No ‘injuries’ observed
de Haan et al (in prep)
Ecosystem effects compared to traditional beam trawl
Reduction in
●Bycatch of undersized fish
●Bycatch of benthic invertebrates
●Penetration depth
Trawl path mortality
●Under study
Change in distribution pattern
●Consequences to be studied
Upscaling experimental results to fleet level
Change distribution pulse trawlers:consequences for ecosystem effects
Tickler chain beam trawls
Pulse trawls
What is still unknown?
Knowledge gaps
Effect on physiology marine organisms (what & why!)
●What type of organisms are sensitive?
●Sensitivity of different life stages
●What is long-term effect on organisms that are exposed repeatedly?
●Effect on electro sense organs (rays and sharks)
Effect on geo-chemistry
●Electrolysis (release of nutrients or contaminants)
Effect on functioning benthic ecosystem
Upscaling effects to fleet level and ecosystem level
Management challenges
What is the range of pulse parameters that is safe for marine organisms?
Technological creep and its implications for sustainable management
Application pulse technique in other fisheries
How to control and enforce the application of pulse techniques?
Research agenda
I. Governance research
II. Economic performances
III.Control and enforcement
IV. Ecological effects (in relation with the technique)
Ecological effects: impact assessment
1. Effect on the by-catch of undersized fish
2. Effect of the use of electricity on marine organisms and the marine ecosystem
3. The development of the pulse technique
1. By-catch of undersized fish
To what extend does the by-catch of undersized fish change when the sole and plaice quota are fished with a fleet of pulse vessels compared to a fleet of traditional beam trawl vessels?
Sub-project 1: Change in by-catch of undersized fish
1.3 Distribution (logbook data, VMS)
1.1 Catch efficiency & selectivity
1.2 Discards monitoring
(part of DCF)
2. Effect of electricity on marine organisms and the marine ecosystem
2.1. PhD-1Lab experiments fish & benthos
2.2. PhD-2Ecosystem functioning
2.3. PhD-3Modelling fleet dynamics & ecosystem functioning
Sub-project 2: Effect of electricity on marine organisms and the ecosystem
2.4. Field experiments:
Effect on seabed ecosystem
2.5. Field strength measurements in
situ
3. Development of the pulse technique
Pulse technique is still under development
Changes must be monitored
Synthesis: Impact assessment of the Dutch North Sea pulse trawl fishery targeting flatfish
Sub-project 3: Monitoring the development of
the pulse technique
Sub-project 1: Change in by-catch of undersized fish
1.3 Distribution (logbook data,
VMS)
1.1 Catch efficiency & selectivity
1.2 Discards monitoring
(part of DCF)
2.1. PhD-1Lab
experiments fish & benthos
2.2. PhD-2Ecosystem functioning
2.3. PhD-3Modelling fleet
dynamics & ecosystem functioning
Sub-project 2: Effect of electricity on marine organisms and the ecosystem
2.4. Field experiments: Effect on sea-
bed ecosystem
2.5. Field strength measurements in
situ
Questions or feedback?