Refining tools for studying cuttlefish (Sepia officinalis) reproduction in captivity: In Vivo sexual determination, tagging and DNA collection

Control of Zootechnology Leads to Improved Cuttlefish (Sepia officinalis, L.) Reproduction Performance up to Pre-industrial Levels

“…In fact, all the DRS of the present experiment were smaller than the ≈ 150 days reported by Boletzky (1987). On the other hand, despite the lower average weight of the cuttlefish used in the present study, when compared with that of the Sykes et al (2013) and Sykes et al (2017b) experiments (≈ 33g in the first when compared with ≈ 46 g in the remaining two studies; F1 and F3 captive generations, respectively), a higher mean duration of the growth stage (DGS) was observed in the present study (≈ 150 days vs. 105 days and 23 days, respectively). Unfortunately, we only have records of cuttlefish age prior to their use in the present experiment (75 days after hatching) and different values might related to the age of animals at the start of each study.…”

“…More recently, Sykes et al (2006a) reported smaller life spans in several consecutive generations cultured in captivity and a possible relation of this smaller life cycle with seawater temperature. Interestingly, the values of duration of the reproduction stage (DRS) could not be related with the increasing tank volumes (Sykes et al, 2013), nor with different sizes of bottom areas (Sykes et al, 2017b), or both (the present paper data). In fact, all the DRS of the present experiment were smaller than the ≈ 150 days reported by Boletzky (1987).…”

“…Afterward, individuals were weighed in a Kern EW6000 (KERN and SOHN GmbH, Germany). To attain this sexual proportion, females and males sex and state of maturity were determined, DNA samples taken (for comparison in future studies related to reproduction in captivity), and cuttlefish tagged according to the protocols described in Sykes et al (2017b). Photos of individuals and of marking details were taken at that time for later identification.…”

“…According to Sykes et al (2017b), sexual discrimination and maturity stage determination in cuttlefish used for reproduction performance studies should be performed through an endoscopy internal examination of the animals. This methodology was applied in the present study, being highly effective (only failed in one tank and displayed an overall accuracy of 99%, similar to that reported by these authors), and allowing for the proper establishment of the sex ratio of 2♀:1♂.…”

“…Moreover, these interactions seem to promote an increased duration of the reproduction period, egg batches and fecundity when the number of females is higher than that of males in a breeding stock/tank. Recently, new technology that allows for in vivo identification of sex and state of maturity was reported by Sykes et al (2017b), which allows for the proper establishment of sex ratios and assurance of an immature state of the cuttlefish individuals used in reproduction studies. This is a pre-requisite for any studies of reproduction performance involving this due to its capacity of retaining active sperm for months (Hanlon et al, 1999).…”