ICES Annual Science Conference 2018

Theme session Q

Co-sponsored by PICES
Sustainability thresholds and ecosystem functioning: the selection, calculation, and use of reference points in fishery management
Tuesday, 25 September

Wednesday, 26 September
Lecture Hall M

​​​​​​Fishery management systems rely on defining biological reference points, which serve as a basis for setting fishing limits and targets and population sizes. These values govern the establishment of harvest specifications and are used to determine whether a stock’s biomass is too low (overfished) and whether fishing intensity is too high (overfishing occurring). In addition, reference points can be critical to harvest rules and management when they contain pre-specified policy measures to be implemented when excessive harvests or depleted biomass occur relative to reference levels. Despite management being reliant on reference points, there are challenges and uncertainties surrounding the choice and calculation of points or proxies and using them in management/policy.

For instance, equilibrium population assumptions underlying the calculation of many reference points are challenged by spatial and temporal variation due to density-dependent mechanisms (recruitment, growth, maturity, and mortality), climate change, variable management and fishing practices, predator-prey dynamics, and myriad other factors. Assuming equilibrium in the presence of regime shifts may limit the reliability and robustness of static reference points, and it remains uncertain whether these changes should be accounted for in a stock management plan.  

Multispecies and ecosystem-level reference points often provide a different view of sustainable harvest levels, because single species approaches do not account for the various trade-offs and uses at the system level. For example, single species FMSY management paradigms form the basis of policy advice provided by ICES (and many countries), but ignore ecosystem aspects (such as carrying capacity and species interactions). Ignoring ecosystem dynamics often leads to FMSY approaches being biased and possibly impeding stock rebuilding initiatives and achievement of MSY. There has been increasing exploration of ecosystem dynamics and indicators that could be used as part of a holistic approach to integrated ecosystem assessment. The basis of management decisions in the coming years must be robust and adaptable in order to deal with the changing environment and complexities of multi-sector resource use. 

This session will explore best practices and new approaches to calculating and selecting reference points in fishery management. Research and case studies on new approaches and best practices that ensure reference points support sustainable fishery management given complex ecosystems, communities, and management aims are welcome. Priority will be given to approaches that are operational in the short to medium term.

Papers are welcome on:

  • Enhancing single species reference point models through incorporation of density-dependent processes, time-varying parameters, spatial components, and climate-related drivers
  • Development of multispecies reference points
  • Development of ecosystem thresholds and reference points
  • Incorporation of socioeconomic factors into biological models to address how fishery removals may be modified to account for alternate resource use metrics
  • Implementation of management strategy evaluations that test the reliability and robustness of reference points
  • Formulation and testing of alternate management procedures and harvest control rules that replace or augment traditional target, trigger, or limit reference points ​
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Daniel R. Goethel (USA)
Henrik Sparholt (Denmark​)​
Aaron M.Berger(USA)
Patrick D.Lynch (USA)
Bjarte Bogstad (Norway​)
Joanne Morgan (Canada)
Xiujuan Shan ​ (China)

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Theme session Q

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