Determination of age and growth of the horned octopus <em>Eledone cirrhosa</em> (Cephalopoda: Octopoda) using stylet increment analysis

Abstract

Summary: Age and growth of the horned octopus Eledone cirrhosa are estimated for the first time by stylet increment analysis. Specimens were collected between March 2009 and March 2010 from the commercial trawl fishery operating off northwestern Iberian coasts. A pool of stylets representing all size classes were defined by means of modal progression analysis performed separately for each sex in northern and western fishing grounds over a total of 2220 individuals (306 males and 595 females from the northern fishing ground; and 379 males and 940 females from the western fishing ground). In total, 122 stylets belonging to individuals with a total weight ranging from 67 to 950 g were successfully analysed. Age of the specimens was estimated assuming a daily deposition rate of growth increments within the stylet. Estimated age of the specimens varied from 106 to 516 days. Differential longevity between sexes was observed, with females reaching a life span of 17 months while males attained reached only 14 months, although the possibility that this difference might be even greater is discussed. Based on estimated age, hatching date was back-calculated and it was concluded that hatching occurs throughout the year, with a peak in winter. Relative instantaneous growth rates estimated for 90-day age classes, ranged from 0.03% to 2.17% of body weight per day, depending on age. The results obtained are compared with the information available on this species.Keywords: Eledone cirrhosa; stylet increment analysis; age; life span; growth; NW Iberian Peninsula.Determinación de la edad y el crecimiento del pulpo blanco Eledone cirrhosa (Cephalopoda: Octopoda) mediante el análisis de incrementos en el estilete Resumen: La edad y el crecimiento del pulpo blanco Eledone cirrhosa son estimados por primera vez mediante el análisis de incrementos del estilete (SIA). Los especímenes fueron obtenidos, entre marzo de 2009 y marzo de 2010, provenientes de la pesquería de arrastre comercial que opera en la costa noroeste de la Península Ibérica. Un conjunto de estiletes, en representación de todas las clases de tamaño, fue definido mediante un análisis de progresión modal realizado por separado para cada sexo en los caladeros del norte y oeste, sobre un total de 2220 individuos (306 machos y 595 hembras procedentes de la costa norte y 379 machos y 940 hembras de la costa oeste). Un total de 122 estiletes, pertenecientes a especímenes con un peso total de entre 67 y 950 g, fueron analizados con éxito. La edad de los especímenes se calculó asumiendo una tasa de deposición diaria de los incrementos de crecimiento en el estilete. La edad estimada de los especímenes fue de entre 106 y 516 días. Se observó una longevidad diferencial entre sexos; en las hembras se registró una esperanza de vida de hasta 17 meses, mientras que los machos tan sólo alcanzaron 14 meses, aunque se discute la posibilidad de que esta diferencia podría ser aún mayor. En base en la edad estimada se calculó la fecha de eclosión, concluyendo que la eclosión se produce duran...

Life histories of Antarctic incirrate octopods (Cephalopoda: Octopoda)

“…In comparison, the quantification of growth increments in stylets of the temperate species Eledone cirrhosa (Lamarck, 1798) from the north Atlantic (living at 11–14°C), suggests a maximum lifespan of 516 days with an G values of 0.97 to 1.15% BM d -1 [77]. Mangold and Boletzky [78] reported a growth rate of 0.9% BM d -1 for O .…”

A review of recent studies on the life history and ecology of European cephalopods with emphasis on species with the greatest commercial fishery and culture potential

“…Studies on stock status are needed in this group, which is of increasing commercial interest. Some progress was made in age determination for E. cirrhosa using stylets (Regueira et al, 2015) and beaks (Ikica et al, 2014).…”

“…The age of E. cirrhosa was estimated using stylets by Regueira et al (2015), who found that lifespan could reach 17 months in the North Atlantic (North West Iberian waters), with instantaneous growth rates ranging from 0.03 % to 2.17 % of body weight per day. In the Adriatic Sea, the beaks of female E. cirrhosa show a higher rate of growth (relative to body size) than in males (Ikica et al, 2014).…”

“…However, the majority of recent publications on these species focused on other aspects of biology, ecology and exploitation. Only one study (Regueira et al, 2015) addresses age estimation of E. cirrhosa.…”