![Page 1: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/1.jpg)
Limits to stock assessments & dynamic ecosystems;model projections for management
Twitter @DickeyCollas
Mark Dickey-Collas & Benjamin Planque
![Page 2: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/2.jpg)
Panorama of stock assessmentsand MSE approaches includes:
Isolated single stock Multispecies
Environmental dynamic Data poor
Ensemble approaches+ +
![Page 3: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/3.jpg)
Why use environmental dynamic?
Improve understanding of past changes byincluding environmental changes/shifts.
Improve predictions for management?
Look further forward than standardstock assessments.
![Page 4: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/4.jpg)
Examples...
ProductivityNorth Sea herring
↘weight, ↗ maturityNorth East Atlantic mackerel
![Page 5: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/5.jpg)
Hatun et al, 2009; Hatun et al 2009
Have the approaches been useful to understand the past?
Blue whiting
![Page 6: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/6.jpg)
Have the approaches been useful to predict the future? Probably no.
Predicted year in which the conditions become suitable for Atlantic cod.Wisz et al. 2015
![Page 7: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/7.jpg)
Have the approaches been useful to predict the future? Probably no.
Simulated biomass of adult cod in the Baltic Sea using 5 different food-web models. Niiranen et al. 2012
![Page 8: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/8.jpg)
Why is prediction beyond short time horizon so difficult? La grande illusion
Was the pet included in the pet model?drawing Juliette Planque
![Page 9: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/9.jpg)
Why is prediction beyond short time horizon so difficult? La grande illusion
“Models might be of limited use to project the future state of marine ecosystems decades into the future because several factors limit predictability; including
● stochasticity ● deterministic chaos ● enablement vs. entailment ● non-ergodicity● ecological surprises ● irreducibility● limits to upscaling.”
![Page 10: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/10.jpg)
La grande illusion
The known
The unknown
The unknownable
Conservation of mass and energy
Gravitation Fluid dynamics
ecological empirical observations
Fish recruitment
How many species
Trophic functional relationships
Complex interactions and the curse of dimensionality
Natural mortality
Single pendulum
![Page 11: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/11.jpg)
La grande illusion
The known
The unknown
The unknownable
Conservation of mass and energy
Gravitation Fluid dynamics
ecological empirical observations
Fish recruitment
How many species
Trophic functional relationships
Complex interactions and the curse of dimensionality
Natural mortality
Single pendulum
Double pendulum
![Page 12: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/12.jpg)
Are models geared up to predict future states? Hazard warning
![Page 13: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/13.jpg)
Are models geared up to predict future states? Hazard warning
Impossible to achieve realism, precision, and generality together.
Model creation requires trade-off of one of these, often in conflict with the desires of end-users.
Models are often employed without consideration of their limitations, such as projecting into unknown space without generalism, or fitting empirical models and inferring causality.
![Page 14: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/14.jpg)
Do we need predictions beyond a few years for robust management?
• Accept we only ever have partial understanding
• We have ongoing monitoring and assessment
• Business planning or fisheries management?
• Adaptive management
• Time line – a few years or longer?
![Page 15: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/15.jpg)
Operational Recommendations
• Keep monitoring and prepare for change• Remain responsive and adapt• Use MSE but don’t trust it
Science 2015
![Page 16: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/16.jpg)
Conclusion
Robust fisheries management is about coping with an unexpected future, not preparing for a predicted future.
![Page 17: Limits to stock assessments & dynamic ecosystems model projections for management](https://reader033.vdocuments.us/reader033/viewer/2022051720/58ed20b71a28ab43498b462f/html5/thumbnails/17.jpg)
Thank you
Picture: Icelandic Wilderness