Fecundity pattern and spawning dynamics of the common cuttlefish Sepia officinalis

The fecundity pattern of common cuttlefish, Sepia officinalis, was assessed in Thermaikos Gulf, one of the species' main fishing grounds in the eastern Mediterranean. Female samples, collected with coastal fishing gears during the population spawning season (January-July), were analysed using a combination of histology and whole mount analysis of ovarian tissue. The potential fecundity was shown to vary seasonally, showing the highest values at the beginning of spawning, gradually dropping thereafter. Previtellogenic oocytes (<0.5 mm) were the most prevalent group occurring throughout the spawning period in all maturity stages. Low or null levels of oocyte recruitment during the spawning period in combination with seasonal drop in fecundity and clutch-specific egg production suggest that the fecundity pattern of cuttlefish displays similarities with the so-called 'determinate fecundity' pattern of fishes. Spent females end up having small reserves of secondary growth oocytes (pre- and vitellogenic) that will never be spawned. Potential annual fecundity was thus estimated as the difference in total fecundity between pre-spawners and spent females and equalled 2569 oocytes/eggs. For a spawning period of four months, the ratio between potential fecundity and clutch size (100-200 eggs) indicated 13-25 different spawning events with a mean interval of 5-9 days.

Automated summary

The study assessed the fecundity pattern of common cuttlefish in Thermaikos Gulf in the eastern Mediterranean. It found that potential fecundity varied seasonally, with the highest values at the beginning of spawning, gradually decreasing thereafter. The pattern of cuttlefish fecundity displayed similarities with the 'determinate fecundity' pattern of fishes, with spent females retaining small reserves of secondary growth oocytes that will not be spawned.