Harvest Control Rules

What are harvest control rules?

Harvest control rules (HCRs) are the operational component of a harvest strategy, essentially pre-agreed guidelines that determine how much fishing can take place, based on indicators of the targeted stock’s status. HCRs range from basic, constant catch strategies—under which catch levels do not change—to complicated, multistep rules that set allowable catch based on triggers.

Empirical vs. Model-Based Harvest Control Rules

How a Harvest Control Rule Works

Stock status can be represented graphically by what is known as a Kobe plot. The example below shows a basic HCR. The fishery’s ideal state is green, its cautionary state is yellow, and the state to avoid is red. The HCR has the following specifications:

1. If biomass is below B_Limit, suspend the fishery and institute a scientific monitoring quota until the limit is reached or exceeded.
2. If biomass is between the limit (B_Limit) and the target (B_Target), reduce fishing mortality in accordance with the rebuilding phase of the HCR.
3. If biomass is greater than or equal to the target (B_Target), fish at the target mortality rate (F_Target).

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