title: Life-history traits of the long-nosed skate Dipturus oxyrinchus.
abstract: This work investigates life-history traits of the long-nosed skate Dipturus oxyrinchus, which is a common by-catch in Sardinian waters. The reproductive variables were analysed from 979 specimens sampled during scientific and commercial hauls. Females (10·4-117·5 cm total length, LT) attained larger sizes than males (14·5-99·5 cm LT). To evaluate age and growth, a sub-sample of 130 individuals (76 females and 54 males) were used. The age was estimated by annuli counts of sectioned vertebral centra. Four models were used for the length-at-age data: the von Bertalanffy, the exponential, the Gompertz and the logistic functions. According to the Akaike's information criterion, the Gompertz model seemed to provide the best fitting curve (L∞mean ± s.e.: 127·55 ± 4·90 cm, k: 0·14 ± 0·09, IP: 3·97 ± 0·90 years). The oldest female and male were aged 17 (115·5 cm LT) and 15 years (96·0 cm LT), respectively. Lengths at maturity were 103·5 cm for females and 91·0 cm for males, corresponding to 90% of the maximum observed length in both sexes. The monthly distribution of maturity stages highlighted an extended reproductive cycle, with spawning females and active males being present almost throughout the year, as confirmed by the gonado-somatic index. Ovarian fecundity reached a maximum of 26 yolked follicles with a mean ± s.e. size of 19·7 ± 6·5 mm.
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Via T. Fiorelli 1, 09126, Cagliari, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Bellodi
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Via T. Fiorelli 1, 09126, Cagliari, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Porcu
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Via T. Fiorelli 1, 09126, Cagliari, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Cannas
authors.affiliation: Department of Architecture, Design and Urban Development, University of Sassari, Palazzo Pou Salit, P.zza Duomo 6, 07041, Alghero, Italy.
authors.forename: Al
authors.initials: A
authors.lastname: Cau
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Via T. Fiorelli 1, 09126, Cagliari, Italy.
authors.forename: M F
authors.initials: MF
authors.lastname: Marongiu
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Via T. Fiorelli 1, 09126, Cagliari, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mulas
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Via T. Fiorelli 1, 09126, Cagliari, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Vittori
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Via T. Fiorelli 1, 09126, Cagliari, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Follesa
mesh_terms: D000365:Age Determination by Skeleton; D063147:Animal Distribution; D025041:Animal Migration; D000818:Animals; D049628:Body Size; D005260:Female; D005298:Fertility; D007558:Italy; D000071421:Life History Traits; D008297:Male; D008954:Models, Biological; D012098:Reproduction; D012741:Sexual Maturation; D012860:Skates, Fish / Q000254:growth & development*; D013131:Spine / Q000254:growth & development
keywords: Mediterranean Sea; age; growth; maturity; reproductive cycle; skate