Investigating temporal variability and influence of condition on fecundity of spotted wolfish (Anarhichas minor) in Icelandic waters

To investigate inter- and intra- annual differences in fecundity, the influence of condition on fecundity and time scale of ovary development, 150 female Atlantic wolffish ( Anarhichas minor ) were sampled in Icelandic waters from 2006–2021. Backwards extrapolation of oocyte size indicates that vitellogenesis begins in December and is likely completed after 8–10 months. There was no evidence of either intra- or inter-annual differences in fecundity, indicating that down-regulation is minimal and that fecundity of spotted wolffish is stable between years. A positive relationship between oocytes size and fish length was detected, while body condition and hepatosomatic index had only a small influence on fecundity in comparison with weight. There was a negative relationship between length and relative fecundity and the exponent of the fecundity–length relationship was lower than exponent of the weight–length relationship. Therefore, total egg production is likely not proportional to the spawning stock biomass of spotted wolffish, and unusually, total egg production would decrease with increasing proportion of larger fish in the population.