Preliminary Management Strategy Evaluation for Blue Shark in the Indian Ocean Using A Data-Limited Approach

In tuna-RFMOs there has been an effort to move to quantitative stock
assessments for pelagic sharks, especially for the main species such as
blue shark Prionace glauca. In IOTC, blue shark was last assessed in
2017 with the use of an integrated length-based age-structured model
(SS3). This paper now presents a preliminary exercise with data-limited
Management Strategy Evaluation (MSE) to test options for different
potential management procedures (MPs), using the data-limited methods
toolkit (DLMtool). Reference points have not yet been adopted for sharks
in IOTC, so for this exercise we set some tentative reference points noting
that those can be updated in the future as needed. Eighty-nine MPs were
evaluated with 9 considered potentially acceptable. Options and tradeoffs
between those MPs are shown and described in the paper. We have
focused mainly on trade-offs between biomass and yield, but according
to the management objectives agreed other performance metrics can be
applied. Even thought this is a preliminary exercise at this point, we hope
that it provides initial thoughts and opens the discussion for the
advancement of the blue shark management and conservation in the
Indian Ocean.