ICES advice on ecological impact of pulse trawl compared to beam trawl for North Sea sole fishery. https://www.ices.dk/news-and-events/news-archive/news/Pages/PulseTrawlAdvice.aspx Pulse trawling is the application of electrical stimulation to replace the conventional mechanical stimulation with tickler chains in the beam trawl fishery for sole. ICES advice is that the change from conventional beam trawling to pulse trawling, when exploiting the total allowable catch (TAC) of North Sea sole (Solea solea), does contribute to reducing the impacts of the sole fishery on the ecosystem and environment.

1. Advice on impacts of pulse trawling for
sole on the ecosystem & environment
Mark Dickey-Collas, Chair ICES Advisory Committee
@ICES_ASC

2. International Council for the Exploration of the Sea
• Science network of 20 countries
• Over 1,500 annually active researchers
• Agreements with countries & EU to provide
advice that is independent of political
influence & subject to best international
quality procedures for scientific advice.
• Only advise governments, international
governmental organisations &
agencies.

3. ICES process for advice

4. History of pulse trawl advice

5. Issues considered across series of requests
• Effects on populations & individuals: sole, plaice, cod, dogfish, undersized fish,
invertebrates on/in seabed
• Suitability of laboratory experiments & field trials
• Characteristics of electric pulse
• Fuel consumption & CO2 production
• Impact on sensitive species & habitats, sea bed disturbance (including Natura)
Overarching theme:
comparison of conventional beam versus pulse trawl when fishing for sole

6. 2020 advice: Impacts of pulse trawling on ecosystem &
environment from sole fishery in North Sea
www.ices.dk/sites/pub/Publication%20Reports/Advice/2020/Special_Requests/nl.2020.03.pdf
Change from conventional beam trawling to pulse trawling (when fishing North Sea sole
TAC) contributes to reducing ecosystem/environmental impacts of sole fishery.
Advice does not consider other forms of electrical fishing, e.g. brown shrimp or
razorshells, nor does it consider pulse fisheries in other ecosystems.
Provided that the sole stock is well-managed, pulse trawling does not impose any
increased risk to its sustainable exploitation.

7. 2020 Advice based on 6 elements:
www.ices.dk/sites/pub/Publication%20Reports/Advice/2020/Special_Requests/nl.2020.03.pdf
1. Evaluating direct harm & long-term adverse consequences to marine
organisms caused by exposure to a commercial pulse stimulus.
Negligible consequences on individuals & populations
2. Evaluating risk to sustainable exploitation of sole from pulse trawling.
No additional risk if fishery well managed
3. Effect on selectivity of sole fishery, discarding of fish, & on benthic
invertebrates.
Improves selectivity for mix of species & size of fish

8. 2020 Advice based on 6 elements:
www.ices.dk/sites/pub/Publication%20Reports/Advice/2020/Special_Requests/nl.2020.03.pdf
4. Effect on the benthic ecosystem of sole fishery.
Substantially reduces impact on benthic ecosystem
5. Impact on sensitive habitats & threatened species/ ecosystems.
Adverse impacts are unlikely on Natura 2000 protected species,
if sensitive seafloor habitats are trawled, less impact than beam
6. Effect on CO2 emissions of the sole fishery.
Fuel consumption reduced at least 37%, so less CO2 emissions

9. Thank you

10. The following slides are the details, if questions arise…

11. 1. Evaluating direct harm & long-term adverse
consequences to marine organisms caused by exposure
to a commercial pulse stimulus.
Exposure to the pulse stimuli may cause spinal injuries in a small percentage of most
fish species, the probability of injury is low (≤ 1%), except for cod (where 35% of the
animals show spinal injuries).
Ecological and population level consequences are assessed to be negligible because
of low exposure rates.
Pulse trawling is unlikely to affect electroreceptive species, (the pulse frequency is
outside the range electroreceptive species sensitivies)
Following exposure to pulse-trawl stimuli, no adverse effects (mortality or lesions)
were found in the ten benthic invertebrate species.

12. 2. Evaluating risk to the sustainable exploitation of
sole from pulse trawling.
Provided the stock is well managed, pulse trawling does not impose any
additional risk to the sustainable exploitation of sole in the North Sea.
It is highly unlikely that pulse trawl stimuli will inflict additional mortality (other
than being caught in a fishery) or compromise the reproductive capacity of
sole that are exposed to pulse trawling, but escape capture.

13. 3. Effect on selectivity of sole fishery, discarding of fish,
& on benthic invertebrates.
Pulse trawling improves the selectivity of the sole fishery by reducing the proportion
of other fish species that are caught, and by reducing the bycatch of undersized fish
for most fish species (discards, prior to implementation of the EU landing obligation)
and benthic invertebrates.
The possible exceptions are sole and whiting, where some discard data suggest catch
efficiency may be higher than with conventional beam trawl.

14. 4. Effect on the benthic ecosystem of sole fishery.
Pulse trawling substantially reduces the impact on the benthic ecosystem in
comparison to conventional beam trawling.
The impact of pulse trawling on the benthic ecosystem is limited to the
mechanical disturbance, which is reduced because less surface area is
trawled at least once per year, reduced penetration into the seabed and
reduced resuspension of sediments.

15. 5. Impact on sensitive habitats & threatened species/
ecosystems.
The available knowledge indicates that adverse impacts are unlikely on Natura 2000
protected species, and are reduced compared to conventional beaming trawling.
The probability of exposure is likely to be very low, and the overall area trawled at least
once per year by the pulse fishery has been reduced compared to conventional beam
trawling.
If sensitive seafloor habitats are trawled, then the expected impact from pulse trawling
will be smaller compared to conventional beam trawling.

16. 6. Effect on CO2 emissions of the sole fishery.
Pulse trawling reduced the estimated fuel consumption by at least 37% compared
to the conventional beam trawling setup using a sumwing.
Assuming that CO2 emissions are proportional to fuel consumption, the reduced
percentages provide an estimate of the reduction in CO2 emissions that can be
achieved when using pulse trawl in the beam trawl fishery for sole.

17. List of properties assessed