Outside Lingcod (Ophiodon elongatus) Stock Assessment for British Columbia in 2025

Abstract

The results below are reported as medians (with 90% credibility intervals in parentheses derived from the base case run). Status The probability that the female spawning stock biomass (B) at the beginning of 2025 is greater than the limit reference point (LRP: 0.2 B0) and candidate upper stock reference points (USRs: 0.35 and 0.4 B0) is > 0.99, placing the outside stock in the Healthy zone of the Precautionary Approach (PA) framework. Current stock status (B2025 / B0) is 1.120 (0.961, 1.290). There is a very high probability (> 0.99) that the fishing mortality rate (F) in 2024 was below all of the candidate removal reference (RR) rates. Trends Annual stock status (Bt / B0) for Outside Lingcod slowly trended downward from 1927 to 1978, then fluctuated on a roughly decadal basis between values of 0.5 and 1.25 until 2025. At no time did the 95% credibility envelope fall below either candidate USR. Ecosystem and Climate Change Considerations Higher recruitment deviations were associated with higher sea floor oxygen, lower sea floor salinity, and lower lagged North Pacific Gyre Oscillation (NPGO). Recruitment deviations were weakly correlated with biomass of surface phytoplankton, smaller copepod species, and Pacific Herring. No single environmental variable appeared to have much predictive power alone. Coastwide indices of average body condition tended to be highest for all sex and maturity classes at the start of the environmental time series (2002). Body condition appeared positively associated with warmer, fresher, and more oxygen-rich water chemistry and Pacific Herring spawning stock biomass (SSB). However, in contrast to recruitment, immature body condition was associated with a higher NPGO index on a two-year lag. Stock Advice Decision tables based on B0 reference points and using constant-catch policies up to 7,000 t/y show: o > 95% probability of remaining above the LRP in 10 years at catches <= 6,500 t/y; o > 90% probability of remaining above both candidate USRs in 10 years at catches <= 5,000 t/y. Candidate TRPs are 0.4, 0.45, and 0.5 B0. The probability of remaining below the three RR rates associated with the candidate TRPs in 10 years at catches <= 4,500 t/y is >= 64%. The Outside Lingcod stock is expected to decline over the next 10 years, even under a no catch scenario as the cohort from the strong 2016 recruitment event ages out of the population. However, the stock is expected to remain above the LRP and candidate USRs with a very high probability (> 99%) at catch levels up to 3,500 t/y (compared to average annual coastwide catches of 1,585 t/y for 2020–2025). Other Management Questions No biological justification was found to support assessing the outside stock at a finer scale than the outside coastwide level (excluding PMFC Area 4B).