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