Current assessment frameworks for trawling impact on seafloor integrity: Lessons learnt from ICES WKBENT on structure, function, tolerance and recoverability Anna Törnroos Åbo Akademi University
Impact on seafloor integrity…. The EU’s Marine Strategy Framework Directive (D6 & D1) State Impact Pressure GES? community + habitat D6 - Sea floor integrity Modified Slide from Daniel van Denderen
Impact on seafloor integrity…. ? ? ? maps indicator ICES WKBENTH report 2017
…some central concepts & principles We have to know… à exposure of benthic habitats to fishing pressures à Sensitivity (measure of effect) of the habitats to fishing pressures …to know impact (if will be further impacted). And… The effect of impact depends on: à the resistance (tolerance - intolerance) of the habitat/community/org. group à the ability of the habitat/community/group to recover ( resilience ). ICES WKBENTH report 2017
Current assessment frameworks for trawling impact on seafloor integrity ICES Special request Advice 2016
Current assessment frameworks for trawling impact on seafloor integrity quantitative categorical regional operational BSII Baltic Sea BH3 (Helcom) BENTHIS Longevity approach** (Rijnsdorp et al.. 2015 ) BQI E Population dynamic approach (PDA)** (Gislason et al. 2017 Leonardsson et al. 2009 (Hiddink et al. 2017 ) BQI O DKI Leonardsson et al. 2015 Henriksen 2014 ) operational Life-history strategy –based indicator Non- BH2 (Beauchard et al . in prep. ) local (Van Hoyen et al. 2013) ** can be integrated Anna T pers. synthesis
Lessons learnt from ICES WKBENT… EU request for guidance on how pressure maps of fishing intensity contribute to an assessment of the state of seabed habitats ICES WKFBI + ICES Advice WKBENTH WKBENTH Workshop to evaluate regional benthic pressure and impact WKTRADE WKSTAKE indictor(s) from bottom fishing 28 Feb – 3 March 2017 ICES Advice (late 2017) * Aim: to evaluate different modelling approaches to assess the extent of impacts at the (sub)regional scale.
“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 on structure, function, tolerance and recoverability
A scientific exercise using the longevity approach in the Baltic Sea ”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. ) State Pressure Impact GES? D6 - Sea floor integrity van Denderen et al. (in prep.)
”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea” Estimating the Pressure (swept area ratio)ç van Denderen et al. (in prep.)
”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea” Predicted longevity distribution (sensitivity) Median longevity of the community = longevity with cumulative biomass proportion is 0.5) van Denderen et al. (in prep.)
”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea” Estimating impact… from longevity comp + depletion(mortality) & recovery rates of benthos Hiddink et al. 2017 van Denderen et al. (in prep.)
”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea” Predicting state of the benthic community Impacted by both fishing disturbance and oxygen depletion van Denderen et al. (in prep.)
”Assessing impact of bottom trawling and hypoxia on seafloor status of the Baltic Sea” What does impact on the longevity mean? ...still in progress Rijnsdorp et al. 2015 Bolam et al. 2017 What does impact on the longevity mean…for function…in the Baltic Sea? 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 van Denderen et al. (in prep.)
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
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