Stock structure of the English Channel common cuttlefish Sepia officinalis (Linnaeus, 1758) during the reproduction period

Abstract

Within the English Channel, the common cuttlefish Sepia officinalis is a semelparous species for which a 2-year life cycle was exclusively described in the 1980s. In the 1990s, new research indicated that whilst a 2-year life cycle was still evident for females and the large majority of males, a small proportion of males were actually maturing at only 1 year of age. Since 1980, the interest of French and UK fishers for this resource has increased and it is nowadays one of the most important demersal species of the area and is considered to be fully exploited. From the start of the 20th century, fishing effort and sea surface temperatures have increased in the English Channel and have probably impacted the life history traits of S. officinalis. A 2-year sampling programme was undertaken at French landing sites of the English Channel during the reproduction season in 2010 and 2011 to estimate if the proportion of 1-year-old mature animals has changed. Age determination was carried out by coupling polymodal decomposition and lipofuscin measurement. Size-at-maturity for each year and each sex was estimated by fitting a binomial error GLM. Results highlight that a variable percentage of males and females belonging to the first cohort are mature and that size-at-maturity was lower than that observed in the 1990s. Finally, different parameters, such as temperature and fishing pressure are explored to discuss changes in life history traits suggesting that cuttlefish could be an indicator of the temperature regime shift in the English Channel.

Shoaling behaviour in the European cuttlefishSepia officinalis

“…We propose that our reported social groups of S. officinalis are linked to the offshore migration pattern of this species. In autumn, English Channel and the Northern part of the French Atlantic Coast (Bloor et al, 2013;Dunn, 1999, see Figure 1 in Gras et al, 2016 andfig. 1.2 in Bloor et al, 2013 for life cycle illustrations).…”

“…In all observations, maturity stages (juvenile, subadult and adult; with subadults being morphologically similar to adults but smaller and not yet reproductively mature (Young & Harman, 1988)) were estimated. This was achieved by assessing their mantle length (there is no proposed guideline for these stages; however, mature individuals [=adults] commonly have a mantle length of at least 12-15 cm in the English channel, see Dunn , 1999;Gras et al, 2016) and analysing their behaviour and body patterns for distinct features commonly expressed in either juvenile/immature or adult/mature cuttlefish, for example reproductive traits for suspected adults (following, e.g. Hanlon & Messenger, 1988, 2018Tinbergen, 1939).…”

Reproductive Biology of the Golden Cuttlefish Sepia esculenta (Cephalopoda, Sepiida)

“…Despite the wide distribution of cuttlefish and their high commercial value, data on their reproductive biology are scarce. Most studies connected to the reproductive biology of cuttlefish have been focused on the following: the determination of the sex ratio; spawning seasons; their size at first maturity and sizes at different maturity stages; the monthly distribution of maturity stages; the calculation of certain reproductive indices; and the development of maturity scales for individual species [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Female reproductive biology has been studied in more detail than that of males.…”

Insight on the reproductive biology of small striped cuttlefish, Sepia prabahari in Gulf of Mannar, Indian Ocean and recommendation for a minimum legal size

“…Morphometrically S. prabahari closely resembles the juveniles of Sepia pharaonis; with the exception of the arm length, tentacular club, sucker ring size and pattern, dorsal mantle pattern and cuttlebone. Reproductive aspects of commercially important cephalopods in general (see reviews by Pierce et al, 2010;Jereb et al, 2015;Lishchenko et al, 2021) and Sepia in particular (Dursun et al, 2013;Salman, 2015;Gras et al, 2016;Sifner et al, 2018;Lin et al, 2019) have been studied in recent years. There is no detailed description on the biology of S. prabahari and the only report is on their population characteristics (Singh, 2005).…”