1. A quantitative assessment of benthic impact from fishing disturbance in the Baltic Sea
Daniel van Denderen
Sebastian Valanko
International Council for
Exploration of the Sea (ICES)
HELCOM BalticBOOST WK
Helsinki, Finland
contribution by network of scientists
policy – science interphase
translators

2. Contribution towards WP3.1?
(1) the big picture (how the project results link to MSFD, GES criteria and environmental targets? What information is needed to make the required assessments?) (2) the proposed guidelines for setting environmental targets for pressures affecting the benthic habitats.
ICES – HELCOM BalticBOOST project workshop WP3.1

3. The big picture?
MSFD requires -> an assessment of whether anthropogenic physical disturbance has adversely affected the seabed habitat and its associated biological communities.
This depends on the sensitivity of the habitat to this disturbance varies according to the habitat type, with some being more resistant to the physical disturbance pressure than others. (Additionally, once adversely affected, the habitats take differing lengths of time to recover to a pre-disturbed state, and may be re-disturbed by subsequent bottom- fishing events before full recovery.)
Thus for MSFD assessments, there is a need to define what constitutes an adverse effect due to physical (fisheries) disturbances by defining threshold values which distinguish between a good state for the benthic habitat and what is considered to be a poor state. This information can be used to assess the extent and distribution of environmental impact from current pressure(s) i.e. fishing.

4. What is required from us?
Assessments being developed within RSC and research projects (e.g. BENTHIS) need to be taken into best practice approach when preparing both benthic pressure and impact indicators. We are thus aiming for the following:
distribution and extent of physical disturbance pressure (e.g. from benthic fisheries) per time period (yearly, 6 yearly) (map at c-square resolution or finer) (distinguishing surface and subsurface pressures; and per metier/gear group) (criterion D6C2)
distribution of adverse effect (from benthic fishing disturbance) per habitat/community type (per 6-year period) (map at highest resolution of habitat maps, e.g. EUSeaMap resolution or finer) (criterion D6C3);
extent of adverse effect per habitat type per subdivision (km2 and % of total extent of habitat in the area) (criterion D6C3).
Mechanistic, 1) longevity and 2)population dynamic model
Categorical, OSPAR BH3, based on MB0101
ICES – HELCOM BalticBOOST project workshop WP3.1

5. Manageable human activity
State
Pressure
D6 - Sea floor integrity
GES?
Manageable human activity
Habitats
Sensitivity
Pressure
Impact (0/1)
Regional specific
Impact
VMS + Log book
community + habitat
VMS (>12m), c-square 0.05o x 0.05o (3km x 3km), + logbook data (>10m)
AIS (>15m) – associated logbook? not enforced, safety issue
Estimate Surface and SubSurface abrasion (Eigaard et al. 2016), SAR surface area ratio
2016 interim EMODNET maps, broad scale level 5 (use info from level 3)
ICES – HELCOM BalticBOOST project workshop WP3.1

6. How to assess sensitivity?
A. Expert-judgement based approach
Disadvantages
Class boundaries arbitrarily defined, not quantitatively linked to pressure
Less appropriate for habitats to regulate pressure
Lack of transparency (expert judgement, typical species)
MB0102 (UK) EUNIS Level 3, MarESA project (improved confidence)
Use detailed level 3 -> generalise up to broad level 5
SAR is continuous scale = method forces it into categorical (1.5 = medium?)
deep sea scored as highly venerable (precautionary)
ICES – HELCOM BalticBOOST project workshop WP3.1

7. How to assess sensitivity?
B. Data-driven quantitative approach
2. Sensitivity – trawling intensity relation
1. Longevity composition of the untrawled community
0.067
0.1
0.05
0.2 1
Trawling
intensity
(1/longevity)
High natural
stress
<-----sites------>
Low natural
stress
Van Denderen et al (2015) MEPS
ICES – HELCOM BalticBOOST project workshop WP3.1

8. Sensitivity of Baltic Sea benthic communities
2268 sampling
stations
Gogina et al. 2016
ICES – HELCOM BalticBOOST project workshop WP3.1

9. Multiple pressures?
Other pressure layers, leading to physical loss and damage to the seabed, can be included as long as there is information on the number of events per year per grid cell
ICES – HELCOM BalticBOOST project workshop WP3.1

10. Sensitivity for multiple pressures
Using the biological trait “vertical position in the seabed” we can select that part of the community that is most affected by a pressure
6 cm 
Bolam et al. (2014)
ICES – HELCOM BalticBOOST project workshop WP3.1

11. Impact for both pressure layers
Total impact (weighted by the biomass in the two sediment layers)
ICES – HELCOM BalticBOOST project workshop WP3.1

12. Combined impact
ICES – HELCOM BalticBOOST project workshop WP3.1

13. Impact per community type
Number of grid cells
ICES – HELCOM BalticBOOST project workshop WP3.1

14. Limitations
Reference state for each community is based on the “best” condition available (not pristine)
Both surface and sub-surface abrasion are assumed to cause 100% mortality on that part of the community affected by the pressure
Data for benthic traits are coming mostly from non-Baltic areas
Communities in Gogina et al. (2016) might not be the “best” areas for management (a similar analysis can be done for EUNIS, HUB or continuous habitat conditions)

15. Recommendations for combining multiple pressures
Use a quantitative approach (ICES advice 2016)
Pressure layers with “similar” effects can be combined with the longevity approach to derive (worst-case) assessment of impact:
Bottom fishing disturbance
Sealing of sediment
Sediment extraction, deposition
Mussel and scallop dredging
Quantification of impact by the pressures is favored, but...
Alternatively, layers can be linked to impact by distinguishing between surface and sub- surface effects
fraction of
area affected

16. Recommendations for setting environmental targets for pressures affecting benthic habitats
Does the approach allow for assessment of whether anthropogenic physical disturbance has adversely affected the seabed habitat and its associated biological communities? Yes
Does the approach allow to distinguish between areas that differ in their sensitivity to disturbance? Yes
Does the method allow to define what constitutes an adverse effect due to physical (fisheries) disturbances? Yes
Can threshold values be distinguish between a good state for the benthic habitat and what is considered to be a poor state? Yes
Can information be used to assess the extent and distribution of environmental impact from current pressure(s) i.e. fishing? Yes

17. Recommendations for setting environmental targets for pressures affecting benthic habitats
Using output of BOOST, consolidate a quantitative approach for assessing impact on benthic habitat/communities at a Baltic-wide scale. Test and improve by:
Use case studies to ground-truth Baltic wide approach (thresholds, longevity)
Combine other pressures in an ecologically meaningful way
Traits to improve longevity and identify benthic goods and services -> allow to explore trade-offs in management options
Workshops in 2017 to review approach and improve robustness
Present management options to stakeholders / managers, based on proposed thresholds and method. Feedback and revision.

18. Next steps for ICES in 2017?
WKBENTH - Workshop to evaluate regional benthic pressure and impact indictor(s) from bottom fishing - 28 February – 3 March 2017
WKSTAKE- Workshop on scoping stakeholders on production of operational guidance on assessment of benthic pressure and impact from bottom fishing - 23 March 2017
WKTRADE- Workshop to evaluate trade-offs between the impact on seafloor habitats and provisions of catch/value.Data for benthic traits are coming mostly from non-Baltic areas March 2017
Review by WGECO, Advice drafting May 2017
Release of Advice to DGENV 12 June 2017

19. Thank you!