Balanced harvesting

Balanced harvesting is a concept that challenges traditional fisheries management approaches. The basic assumption is that by harvesting moderately (“balanced”) across all trophic levels and species, more protein may be extracted from the oceans and it will be done in a more sustainable manner, avoiding overexploitation.  It is recognized that this will involve harvesting of less-desirable species, which we may assume will lead to more use for, e.g., small pelagics for fish meal and oil for aquaculture or zooplankton for Omega-3 fatty acid extraction (“Calanus oil”).

Using EwE to address this question would allow for a comparison of balanced harvesting and traditional management approaches. You could set up different scenarios representing various implementations of balanced harvesting (e.g., perfectly balanced, partially balanced) and compare them to scenarios of traditional size-selective management.

These analyses can provide insights into the potential benefits and drawbacks of balanced harvesting as an ecosystem-based fisheries management approach. It may help identify conditions under which balanced harvesting might be most beneficial, as well as potential risks or unintended consequences. The results could inform policy discussions and help guide future fisheries management strategies.

For implementation, it could be a reasonable assumption that harvest balancing should be based on setting a fishing pressure that is proportional to each groups P/B.  Further, decisions have to be made on which groups to include, e.g., should zooplankton be harvested? Should certain groups be protected?

Potential policy questions

1. Biodiversity impacts: How do balanced harvesting and traditional management approaches differ in their effects on species diversity and functional diversity?
2. Trophic structure: How does each management approach affect the overall trophic structure and energy flow within the ecosystem?
3. Ecosystem resilience: Which management approach results in a more resilient ecosystem in the face of environmental perturbations or climate change?
4. Fisheries yield: How do total fisheries yields compare between balanced harvesting and traditional management under various scenarios?
5. Economic considerations: What are the economic implications of shifting to balanced harvesting in terms of catch value, processing costs, and market demand?
6. Bycatch and discards: How does balanced harvesting affect bycatch rates and discard practices compared to traditional management?
7. Gear selectivity: What changes in fishing gear and practices would be required to implement balanced harvesting, and how feasible are these?
8. Ecosystem indicators: How do key ecosystem indicators (e.g., mean trophic level, biomass ratios) respond under each management approach?
9. Species-specific responses: Are there particular species or functional groups that benefit or suffer disproportionately under balanced harvesting compared to traditional management?
10. Recruitment dynamics: How does each management approach affect recruitment processes and population age structures?
11. Ecosystem services: Beyond fisheries, how do the two approaches compare in maintaining other ecosystem services such as carbon sequestration or nutrient cycling?
12. Implementation challenges: What are the practical challenges of implementing balanced harvesting, and how might these be addressed in the model?
13. Recovery scenarios: For overexploited ecosystems, how do recovery trajectories differ under balanced harvesting versus traditional rebuilding strategies?
14. Spatial considerations: How might the effects of balanced harvesting vary across different habitat types or in spatially heterogeneous ecosystems?
15. Time scales: What are the short-term versus long-term ecosystem responses to each management approach?
16. Mixed strategies: Are there hybrid approaches combining elements of balanced harvesting and traditional management that might optimize outcomes?
17. Uncertainty and risk: How do the two approaches compare in terms of ecosystem and fisheries outcomes under scenarios of high uncertainty or environmental variability?