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Checks in the statolith microstructure of the short-finned squid, Illex coindetii from the Strait of Sicily (central Mediterranean)

Published online by Cambridge University Press:  01 December 1999

Alexander Arkhipkin
Affiliation:
Atlantic Research Institute of Marine Fisheries and Oceanography (AtlantNIRO), 5 Dmitry Donskoy Street, Kaliningrad, 236000, Russia Falkland Islands Government Fisheries Department, PO Box 598, Stanley, Falkland Islands
Patrizia Jereb
Affiliation:
Istituto di Ricerche sulle Risorse Marine e l'Ambiente—Consiglio Nazionale delle Ricerche (IRMA-CNR), Via Luigi Vaccara 61, Mazara del Vallo, 91026, Italy
Sergio Ragonese
Affiliation:
Istituto di Ricerche sulle Risorse Marine e l'Ambiente—Consiglio Nazionale delle Ricerche (IRMA-CNR), Via Luigi Vaccara 61, Mazara del Vallo, 91026, Italy

Abstract

Microstructural prominent discontinuities (checks) were observed within the statoliths of the short-finned squid Illex coindetii from the Strait of Sicily. Two hundred and forty-two pairs of statoliths were extracted from specimens (52–175 mm of mantle length, ML) sampled during autumn 1995 and analysed. Beside the check delimiting the postnuclear zone, up to four peripheral checks were detected in the peripheral zone. The occurrence of peripheral checks in the statoliths of immature squid was low (5–15%), whereas 80–95% of mature squid had peripheral checks. The mean number of peripheral checks within statoliths of mature males and females did not differ significantly (1.53–1.68 peripheral checks per squid). In mature and spawning females, the number of peripheral checks corresponded well with the number of spermatophoric bundles inside the mantles. Age at peripheral check formation was estimated for each sex, indicating that the first peripheral check formed at a significantly younger age in males than in females. Formation of the first peripheral check coincided with the start of maturation in both sexes, at a wide age range. The number of increments between peripheral checks subsequent to the first one declined sharply and remained similar in the two sexes, with a predominant mode between three and seven increments. A possible relationship between the number of peripheral checks and mating events in I. coindetii is discussed.

Type
Research Article
Copyright
© 1999 Marine Biological Association of the United Kingdom

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