Report of the Eighth Workshop on the Development of Quantitative Assessment Methodologies based on LIFE-hisory traits, exploitation characteristics, and other relevant parameters for data-limited stocks (WKLIFEVIII)

The Workshop on the Development of Quantitative Assessment Methodologies based on Life-history traits, exploitation characteristics, and other relevant parameters for stocks in categories 3–6 (WKLIFE VIII), chaired by Carl O'Brien (UK) and Manuela Azevedo (Portugal) met in Lisbon, Portugal, 8–12 October 2018, to further develop methods for stock assessment and catch advice for stocks in categories 3–6, focusing on the provision of sound advice rules that are within the ICES MSY framework. 

Two new MSY-based advice rules for the stochastic surplus production model in con-tinuous time (SPiCT) have been investigated. While the first advice rule allows to scale the total allowable catch (TAC) according to the uncertainty of the assessment (MSY rule) specifying any fractile for the distributions: F/F_MSY, B_pred/B_MSY, C^pred, the second advice rule (MSY-PA) takes assessment uncertainty into account by including a pre-cautionary buffer depending on the probability of the predicted biomass being below a given reference level (e.g. B_lim). To derive adequate advice rules for stocks suitable for a SPiCT assessment in categories 3 and 4 the following decision tree is proposed:

Additionally, the performance of the 3.2.1 catch rule can be improved in terms of risk by applying a multiplier. Last year in WKLIFE VII, based on a limited number of sim-ulations (only four representative stocks), a multiplier of 0.95 was proposed independ-ent of k. This year, to keep the probability of dropping below B_lim to 5% or less, and based on a larger number of stocks representing a wide range of life-history character-istics, simulations indicated a revision of this proposal incorporating k. If a multiplier were to be used independent of k, a multiplier of no greater than 0.8 is recommended. If a multiplier were to be used depending on the value of k, then for k values in the range of 0.08–0.19, a multiplier of no greater than 0.85 is recommended, and for k values in the range of 0.20–0.32, a multiplier of no greater than 0.90 is recommended. For k values above 0.32, the 3.2.1 catch rule should not be applied in its current form. 

A number of harvest control rules (HCRs) using length-based indicators appropriate to the management of elasmobranch stocks were investigated prior to, and during, WKLIFE VIII.  Simulation results based upon the cuckoo ray (Leucoraja naevus L.) are presented and future directions for work within WKLIFE are presented.
A number of promising approaches for short-lived species have been presented and discussed during both WKLIFE VII and WKLIFE VIII; however, the results are still preliminary, and the models require further improvement.  To rectify this, a recom-mendation to convene an ICES Workshop of Data-limited short-lived species early next year (2019) has been proposed that addresses both assessment methods and long-term management strategy evaluations.  Two co-chairs have been identified.
Lastly, it is recommended that there be a ninth meeting of WKLIFE in Lisbon, Portugal next year (2019), whose Terms of Reference should be discussed by ACOM at their November 2018 consultation meeting.