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Based on simulation evaluations of candidate harvest control rules by Adam and Bentley (2013),
Bentley and Adam (2014a,b, 2015, 2016), reviewed and endorsed by the Working Party on
Tropical Tunas (WPTT), Working Party on Methods (WPM), and the Scientific Committee
(SC), the IOTC adopted Resolution 16/02 “On Harvest Control Rules for Skipjack in the IOTC
Area of Competence.” This described the harvest control rule (HCR) to be used for setting a
recommended catch for skipjack (SKJ) and stated that its first implementation will be based
upon the 2017 stock assessment agreed by the WPTT and then endorsed by SC. Implementation
of the HCR to give a recommended catch limit for 2018–2020 is described in IOTC (2017a). The
Resolution also requested a further review and possible modification of the HCR to be conducted
no later than 2021.
In 2018, the IOTC WPM noted that the SKJ HCR is not a fully specified Management Procedure
(MP), since the underlying data required and assessment methodology are not part of Resolution
16/02. Hence the WPM suggested that the review and potential revision required under Resolution
16/02 be conducted with the aim of determining a full MP for SKJ. This was noted by the SC in
2018.
An MP includes the assessment or estimation method on which the HCR is based, as well as the
data inputs and the HCR itself. To be fully specified therefore, a suitable assessment method is
required: one that is capable of forming the basis for implementation of the HCR but simple
enough to simulation test. A biomass dynamic model could fulfill these requirements. Developing
such a model provides the motivation and basis for the current work.
