Current assessment frameworks for trawling impact on seafloor - - PowerPoint PPT Presentation

Current assessment frameworks for trawling impact on seafloor integrity:

Lessons learnt from ICES WKBENT

• n structure, function, tolerance and recoverability

Anna Törnroos Åbo Akademi University

community + habitat

Modified Slide from Daniel van Denderen

State

Pressure

D6 - Sea floor integrity

GES?

Impact

Impact on seafloor integrity….

The EU’s Marine Strategy Framework Directive (D6 & D1)

maps indicator

? ? ?

Impact on seafloor integrity….

ICES WKBENTH report 2017

…some central concepts & principles

ICES WKBENTH report 2017 We have to know… à exposure of benthic habitats to fishing pressures à Sensitivity (measure of effect) of the habitats to fishing pressures And… The effect of impact depends on: à the ability of the habitat/community/group to recover (resilience). …to know impact (if will be further impacted). à the resistance (tolerance - intolerance) of the habitat/community/org. group

ICES Special request Advice 2016

Current assessment frameworks for trawling impact on seafloor integrity

Current assessment frameworks for trawling impact on seafloor integrity

BENTHIS Longevity approach**

(Rijnsdorp et al.. 2015 )

Population dynamic approach (PDA)**

(Hiddink et al. 2017 )

BH2

(Van Hoyen et al. 2013)

BH3 Life-history strategy –based indicator

(Beauchard et al. in prep. )

BQIE DKI BQIO regional BSII Baltic Sea

(Helcom)

local quantitative categorical

• perational

Non-

• perational

** can be integrated (Gislason et al. 2017

Leonardsson et al. 2009 Leonardsson et al. 2015 Henriksen 2014 )

Anna T pers. synthesis

WKBENTH Workshop to evaluate regional benthic pressure and impact indictor(s) from bottom fishing 28 Feb – 3 March 2017

Lessons learnt from ICES WKBENT…

EU request for guidance on how pressure maps of fishing intensity contribute to an assessment of the state

• f seabed habitats

* Aim: to evaluate different modelling approaches to assess the extent of impacts at the (sub)regional scale.

ICES WKFBI + ICES Advice

WKTRADE WKSTAKE WKBENTH

ICES Advice (late 2017)

“Lessons learnt” from ICES WKBENT…

Some main points…

• Impact of the different assessment approaches differed in the absolute value, but

show overall similarity.

• There is a recommendation to progress with quantitative approaches (Longevity and PDA)
• However, quantitative approaches do not (either) provide measure of function…but technically possible
• Importantly! Most datasets lack “real” undisturbed conditions

and a ”minor”…

• Some approaches lack validation for epifauna (Benthis & PDA at least)

ICES WKBENTH report 2017

Lessons learnt from ICES WKBENT

• n structure, function, tolerance and recoverability

”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea”

PD van Denderen, R Friedland, JG Hiddink, K Norén, AD Rijnsdorp, M Sköld, A Törnroos & S Valanko (in prep.)

A scientific exercise using the longevity approach in the Baltic Sea

State

van Denderen et al. (in prep.)

D6 - Sea floor integrity

GES?

Pressure

Impact

Estimating the Pressure (swept area ratio)ç

”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea”

van Denderen et al. (in prep.)

”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea”

van Denderen et al. (in prep.)

Predicted longevity distribution (sensitivity)

Median longevity of the community = longevity with cumulative biomass proportion is 0.5)

”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea”

van Denderen et al. (in prep.)

from longevity comp + depletion(mortality) & recovery rates of benthos

Estimating impact…

Hiddink et al. 2017

”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea”

van Denderen et al. (in prep.)

Predicting state of the benthic community

Impacted by both fishing disturbance and oxygen depletion

...still in progress ”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea”

van Denderen et al. (in prep.)

What does impact on the longevity mean?

Rijnsdorp et al. 2015 Bolam et al. 2017

Research proposal Anna Törnroos: Safeguarding seafloor functioning under human pressure: towards a trait- based assessment framework of trawling and hypoxia in the Baltic Sea ecosystem What does impact on the longevity mean…for function…in the Baltic Sea?

Current assessment frameworks…lessons learnt/status…future progression

Take homes:

• Current frameworks – Pros & Cons (synthesized in e.g. ICES WKBENTH report)
• Possible (seem to be ecologically sound) way to include multiple pressures with the

Longevity/PDA approach for the Baltic Sea

• Big Pro would be to address some functional aspect (otherwise possible redo when

we have operational indices, because we anyway need to clarify what set thresholds should lead to) à However!!…need for a discussion on what function as well….

What functions to encompass…?

ICES WKBENTH Report 2017

What functions to encompass…?

ICES WKBENTH Report 2017

Traits in the assessments….

ICES WKBENTH Report 2017