IS SPAWNER BIOMASS A SENSITIVE MEASURE OF THE REPRODUCTIVE AND RECRUITMENT POTENTIAL OF NORTHEAST ARCTIC COD

The assumption that spawner biomass is directly proportional to total egg production by fish stocks underlies most spawner-recruit relations hips. Despite its importance, this assumption is largely untested. Dat a describing the reproductive potential of Northeast Arctic (NEA) Atla ntic cod (Gadus morhua) were used to test the proportionality assumpti on for a period showing strong variation in condition and, abundance o f spawners. At the individual scale, relative fecundity varied with le ngth and condition. This decreases the likelihood that the proportiona lity assumption is valid. At the stock level, total egg production was estimated (1985-1996) using acoustic estimates of total abundance and demographic information from trawl sampling in combination with year- specific fecundity-length relationships. For NEA cod, spawner biomass estimated bg virtual population analysis (VPA) was not proportional to total egg production. Compared with VPA-based estimates of spawner bi omass, total egg production is an improved index of recruitment potent ial because (i) the magnitude of variation observed in total egg produ ction was closer to that observed in recruitment and (ii) the relation ship between recruitment at age 1 and total egg production approaches the origin. The results suggest that further progress in explaining re cruitment variation will be achieved using more sensitive measures of the true reproductive potential of the stock.