Forage fish exploitation

Are there cascading ecological effects associated with forage fish exploitation?

This overarching question can be explored using EwE to model different scenarios of forage fish exploitation and evaluate the ecosystem-wide consequences.

The question addresses a critical issue in marine ecosystem management, as forage fishes play a crucial role in transferring energy from lower to higher trophic levels. Their exploitation can have far-reaching consequences throughout the ecosystem, affecting not only the targeted species but also a wide range of predators, including many species of commercial and conservation importance.  Notably, we often see that exploitation of forage fish has direct and immediate consequences for their predators: increased fishing mortality is compensated by reduced predation mortality due to decrease in predator abundance.  The result is that forage fish may be impacted less by fisheries than their predators.

Using EwE to explore this question may provide valuable insights into the complex dynamics of marine ecosystems and help inform more inclusive, ecosystem-based management approaches for forage fish fisheries.

Potential policy questions

1. Trophic impacts: How does changes in forage fish biomass affect their predators (e.g., seabirds, marine mammals, larger fish) and their prey?
2. Energy flow alterations: Does forage fish exploitation change the energy transfer efficiency through the food web?
3. Alternative stable states: Are there threshold levels of forage fish biomass that, if crossed, could lead to shifts in ecosystem structure?
4. Competition effects: How does changes in forage fish population size impact the competitive relationships between other species in the ecosystem?
5. Fishery interactions: What are the indirect effects on other fisheries that target predators of forage fish?
6. Recovery potential: How resilient is the ecosystem to different levels of forage fish depletion, and what are the timescales for recovery?
7. Spatial considerations: How do the impacts of forage fish exploitation vary spatially, especially in relation to important breeding or feeding grounds for dependent predators?
8. Climate change interactions: How might the impacts of forage fish exploitation be exacerbated or mitigated by ongoing climate change?
9. Management strategies: What harvest control rules could be used to ensure sustainable forage fish exploitation?
10. Socio-economic trade-offs: How can the economic value of the forage fish fishery be balanced against the ecosystem services provided by abundant forage fish populations?

Question 1: Trophic impacts