Growth and reproduction of the squid Illex coindetii Verany, 1839 in the central Mediterranean Sea

Abstract

Life span, growth and cost of reproduction of Illex coindetii were examined for the first time in the southern Adriatic Sea, central Mediterranean Sea. Age and growth were investigated through statoliths reading. Cost of reproduction was explored by studying the relative investment between somatic and gonad growth. The life span of I. coindetii was less than nine months in both sexes. Females (128-234 days) showed longer life span than males (124-178 days). In both sexes the linear model best described the mantle length-at age data, while the exponential model provided the best fit to the total weight-at-age data. In terms of mantle length, females grew faster than males (average growth rate was 1.33 mm day- 1 in females and 1.00 mm day-1 in males). In terms of total weight, no significant differences were highlighted between growth curves of males and females. Mantle length, total weight, mantle weight and fin weight increased up to the latest maturity stage in both sexes. Immature and maturing individuals showed poorer body condition than mature counterparts in both sexes. Some evidences of a reproductive strategy more similar to a multiple-spawning than to a single-spawning species were found.

Basic Parameters for Assessment and Management of the Short-Finned Squid Illex coindetii (Verany, 1839) (Cephalopoda, Ommastrephidae) from the deep water off the Egyptian Mediterranean Sea.

“…The growth and lifespan of Illex coindetii were examined for the first time from fishing in deep water off the Egyptian Mediterranean Sea noted two age groups with zero group of male and three age groups with zero group of females and sexes combined. This is comparable to (González et al, 1996;Sánchez et al, 1998;Arkhipkin et al, 2000Ceriola et al 2016) stated that the lifespan of females I. coindetii usually showed a faster growth rate and longer than males. Table ( 5) shows that lifespan estimates of I. coindetii vary from (6 to 24 months).…”

“…(Mangold-Wirz, 1963a) in the western Mediterranean Sea, used length frequency analysis and concluded that the life span 20 and 24 months for males and females respectively. (Ceriola and Milone 2016) recorded female lifespan ranged from128 to 234 days longer than males 124-178 days. The variances in lifespan are due to the differences of individual size in the sample and in environmental condition especially temperature which affected on growth.…”

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

“…As recorded elsewhere in its range, in the East Mediterranean (Adriatic and Aegean Seas), I. coindetii is an intermittent terminal spawner (Ceriola and Milone, 2017;Salman, 2017). Alongside the apparent expansion of the species into the Northern North Sea and Baltic Sea Oesterwind and Schaber, 2020), there is now evidence of a summer spawning stock of Illex coindetii in the North Sea.…”