EBS Pollock Stock Assessment Update Checklist (2025)
Data updates
Model inputs and structure
Model runs and diagnostics
Reference points and projections
Document and presentation updates
Notes: Acoustic-trawl biomass index is static at 2024; only ATS ages are updated. AVO index extends to 2025. Main survey input is 2025 BTS.
Responses to 2024 SSC Comments
Dynamic Species Environment Models (DSEM) and recruitment mechanisms
The SSC recommended further exploration of DSEM to reconcile contrasting signals such as record larval biomass in 2024, low age-0 abundance, chronically low condition, and increasing adult biomass.
In 2025, exploratory DSEM analyses continue under the ESR framework. No new results are incorporated into the current assessment, but anomalous recruitment indicators are highlighted in the Recruitment section for context.
Pollock cannibalism index
The SSC requested extrapolation of the index to biomass consumed.
For 2025, the index is updated. Work is underway to provide biomass-consumed estimates, though results are not yet finalized. This remains a development priority.
Tier 1 vs. Tier 3 classification
The SSC supported Tier 3 classification given reliance on priors and limited data at low stock sizes.
The 2025 assessment maintains Tier 3a status. Tier 1 calculations are not carried forward, consistent with SSC guidance.
Multispecies model outputs
The SSC encouraged use of time-varying mortality or consumption estimates from the multispecies model, noting its strategic role in climate planning.
In 2025, no direct integration of multispecies outputs occurred. These remain under review for potential use in ESP indicators and future assessment development.
Biological observations
The SSC noted low weight-at-age and condition in recent years and emphasized the importance of the 2018 year class.
The 2025 BTS confirms condition remains below average. The 2018 year class continues to dominate spawning biomass but shows expected decline as it ages out of the population.
Selectivity assumptions
The SSC supported the use of the five-year moving average selectivity for projections.
This method is retained in 2025, with updated retrospective diagnostics.
Model status and diagnostics
The SSC endorsed Model 23.0, Tier 3a classification, and ABC equal to the maximum permissible.
Model 23.0 is retained for 2025 with updated data inputs. Tier 3a status and ABC recommendations remain as supported by the SSC.
Additional recommendations
- State-space approach (TMB/RTMB): exploratory work is ongoing.
- Russian proportion/movement: no new estimates available for 2025.
- FT-NIR age validation: further evaluation continues; integration not yet implemented.
- Recruitment penalty (2018 cohort): sensitivity analyses are included; discussion of penalty influence is provided.
Stock–Recruitment relationship
The SSC noted reduced influence under Tier 3, but stressed unbiased estimation of recruitment deviates and transparent use of steepness priors.
Recruitment is estimated without bias correction; steepness priors remain meta-analysis based. No Tier 1 analyses are presented.
Documentation request
The SSC requested that the September 2024 SRR document be included as an appendix or linked.
The document has been added as Appendix X in this SAFE.
SSC 2024 Comments and 2025 Responses
| SSC Comment | 2025 Response |
|---|---|
| Explore use of DSEM for pollock recruitment anomalies | Highlighted anomalies in Recruitment section; exploratory analyses ongoing, no integration yet. |
| Extrapolate cannibalism index to biomass consumed | Index updated; extrapolated biomass estimates in development, not finalized. |
| Tier 1 vs. Tier 3 classification | Maintained Tier 3a classification; Tier 1 calculations not carried forward. |
| Use multispecies model outputs (time-varying M, consumption) | No direct integration in 2025; retained for ESP and future assessment consideration. |
| Biological observations (low condition, 2018 year class) | 2025 BTS confirms below-average condition; 2018 cohort still dominant but declining. |
| Use of five-year moving average selectivity | Retained for 2025 projections; retrospective diagnostics updated. |
| Endorse Model 23.0, Tier 3a, ABC=max permissible | Continued use of Model 23.0; Tier 3a classification; ABC set equal to maximum permissible. |
| Recommendations: state-space approach, Russian distribution, FT-NIR, recruitment penalty | State-space exploration ongoing; no new Russian estimates; FT-NIR evaluation continues; penalty influence discussed with sensitivity runs. |
| Stock–recruitment relationship | SRR not carried forward; recruitment deviates estimated unbiasedly; steepness prior remains meta-analysis based. |
| Add Sept 2024 SRR document as appendix | Document included as Appendix X. |