Use of parameters within Euphausia superba Grym simulations

• Main Authors: Maschette, D, Wotherspoon, S
• Format: Conference Object
• Language: English
• Published: CCAMLR 2021
• Subjects: Agricultural; Veterinary and Food Sciences; Fisheries sciences; Fisheries management; Paras; Euphausia superba
• Online Access: https://meetings.ccamlr.org/en/wg-fsa-2021/40; http://ecite.utas.edu.au/155008

The SC-CAMLR last estimated a precautionary harvest rate (gamma) used for managementadvice in the Area 48 krill fisheries in 2007 (SC-CAMLR, 2007 Annex 4 paras. 2.38-2.39).Subsequently, a range of various methods have been tried, with limited success, to produceboth input parameters and stock assessments which can be used for management advice.Following the work plan outlined by SC-CAMLR (2019, Annex 4 paras. 2.60 2.64) endorsedby the Commission (CCAMLR, 2019, para. 5.53) the Generalised Yield Model (GYM)software was reimplemented in R as the Grym package, with the intention of updating theprevious krill assessment. However, the methods used to estimate some input parameters to theprevious assessment were not documented in detail, and there remains considerable ambiguityas to how to compute these inputs, and how these inputs are used within the assessmentsimulations.Here we aim to clarify what each parameter within the Grym models are used for, and wherepossible provide examples as to how they have been calculated.