Reproductive characteristics of three small-bodied cuttlefish in subtropical waters

Abstract

Life history information for many commercially important cuttlefish is lacking, and thus the effects of long-term harvest remain unknown. The present study investigated the reproductive mode and seasonality of three small-bodied cuttlefish (Sepia opipara, S. plangon and S. rozella) in subtropical eastern Australia. Monthly samples were collected over 2 years and examined for gonadal development, size at sexual maturity, potential fecundity, size of mature oocytes and spermatophores, and temporal variation in maturity stages and gonadal weight relative to seawater temperature. All species showed reproductive characteristics consistent with a terminal multiple spawning mode, with S. opipara and S. rozella likely to be intermittent batch spawners, whereas S. plangon spawned continuously. Spawning occurred year round for all species, but S. opipara and S. rozella showed greater seasonality than S. plangon, peaking in autumn–spring. The biggest species, S. opipara, matured at a larger size than the others, had the greatest potential fecundity (the highest documented for any cuttlefish) and the largest spermatophore sizes. In contrast, S. rozella and S. plangon had much larger mature oocytes than S. opipara. These results further highlight the diversity of reproductive characteristics in cuttlefish, and the need for species-specific information for fishery and conservation management plans.