Second Science Management Dialogue

SC19 recommended that WCPFC20 review a list of candidate Target Reference Points (TRPs) as outlined in the document SC19-MI-WP-03 (Update to further inform discussions on South Pacific albacore objectives and the TRP). The recommendation was to consider adopting a TRP for South Pacific albacore that is based on a set of reference years rather than a specific level based on biomass depletion percentage.

Subsequently, at WCPFC20, after discussions in a small working group, the Commission agreed on an iTRP for South Pacific albacore. This iTRP was specified as 0.96 SB2017-2019/SBF=0[1], to maintain the South Pacific albacore stock around this level on average when implementing a management procedure. It was also noted that this iTRP would be subject to review following the 2024 stock assessment and the further development of candidate management procedures.

Furthermore, WCPFC20 tasked the SSP to undertake evaluation of a range of alternative candidate South Pacific albacore target reference points between SB/SBF=0 = 0.42 – 0.56 (long-term average SB/SBF=0 (WCPF-CA), or preferably equivalent levels defined in terms of a reference period) that will be considered in the context of the review of the adopted iTRP.

The SSP presented the preliminary results of WCPFC20 requests at the SC20 (SC20-MI-WP-03) and advised SC20 to review the recalibrated iTRP depletion value and its implications for fishing levels, alternative depletion levels, and management actions while requesting guidance on the methodology for longline catch-based projections. 

SC20 recommended that both catch numbers and catch weight be evaluated as the basis for projections to support the review of the interim TRP for South Pacific albacore, and advised the SSP to present outcomes for vulnerable biomass for key fleets, and, for WCPFC21, to perform analyses that related to catch levels at 2017-2019 levels.

SMD02 will further review the progress made since SC20 and provide recommendations to the Commission for the adoption of interim TRP for South Pacific albacore.

[1] Technical definitions:

“Spawning potential depletion” refers to the estimated South Pacific albacore spawning potential as a percentage of the estimated spawning potential in the absence of fishing (i.e., the unfished spawning potential). The metric is dynamic and is estimated for each model time step.

The method to be used in calculating spawning potential in the absence of fishing (SBF=0) shall be:

1. SBF=0, t1-t2 is the average of the estimated spawning potential in the absence of fishing for a time window of ten years based on the most recent South Pacific albacore stock assessment, where t1=y-10 to t2=y-1 where y is the year under consideration; and
2. The estimation shall be based on the relevant estimates of recruitment that have been adjusted to reflect conditions without fishing according to the stock recruitment relationship.