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rfb rule
Simon Fischer edited this page Jun 13, 2024
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- The previous 2 over 3 rule calculated catch advice based on the trend from a bio-mass index. In addition to this, the rfb rule also considers (1) the exploitation of the stock based on catch-length data and (2) includes a biomass safeguard that reduces the catch advice if the biomass index falls below a trigger value. The catch advice calculated with the rfb rule is a result of all these considerations combined. Furthermore, the trend in the biomass index is calculated by using data from the most recent five years, i.e. an increase in the index in a single year does not necessarily result in a positive biomass trend.
## What to do if new life-history parameters such as L∞ are found; is there a need to recalculate things back in time?
- There is no need to annually update life-history parameters. If new growth pa-rameters are available and these are substantially different from previous esti-mates, these should be used. To ensure consistency in the calculation, derived values such as the reference length LF=M should also be updated and the historical mean catch length compared to this new reference length. Growth parameters and derived metrics such as the reference length should be periodically reevalu-ated, e.g. every 3-5 years, following a similar schedule to benchmarks for Catego-ry 1 data-rich stocks, but kept constant in-between unless there is compelling new evidence for a change.