Increasing the precision of the daily egg production method; 2020’s remix of a 1980’s classic

Abstract This paper reviews application of the Daily Egg Production Method (DEPM) to sardine (Sardinops sagax) off southern Australia between 1995 and 2019. Coefficients variation (CVs) estimates spawning biomass (SB) were reduced from 23–59% 8–12% by: (i) estimating mean daily egg production (P0), fraction (S), sex ratio (R) all historical data rather than annually; (ii) combining batch fecundity (F) female weight (W) into a single parameter, relative (F′ = F^/W). Total was estimated most precisely annual area (A) P0 obtained data. Both S R Estimating W F did not increase precision. F′ had lower CVs both F, stable across years wide range W. Findings demonstrate that A can be converted precise SB using P0, S, R, However, possibility DEPM parameters may change in future cannot discounted. Future monitoring should include estimation periodic (e.g. 3–5 years) re-estimation adult parameters.