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    Morphometrics, maturity and movement of the Antarctic skates Amblyraja georgiana and Bathyraja eatonii in the Ross Sea

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    M.P. Francis and N.W. McL. Smith (New Zealand)
    Agenda Item(s)

    Regression equations relating total length (TL), pelvic length, disc width and weight are provided for Amblyraja georgiana by sex, and for both sexes combined. For all regressions, there were significant differences between the two sexes: females are broader and heavier than males at lengths greater than about 90 cm TL. There were insufficient data to adequately define length-length and length-weight relationships for Bathyraja eatonii, but preliminary regressions are provided for the two sexes combined. It is probable that large females are larger and heavier than males of the same size. The regressions for these species should be used with caution.
    The length at 50% maturity for male A. georgiana is about 91 cm TL, and females appear to mature at a similar or slightly greater length. The length at 50% maturity of male and female B. eatonii could not be accurately determined, but may be around 90–100 cm, and greater than 100 cm, respectively.
    To date, c. 6000 skates have been tagged in sub-area 88.1 over the 1999–2000 through 2001–02 seasons. Returns suggest some long-term survival, small-scale migration within-season, and limited movement between seasons. Results are considered preliminary, given the short time span of the programme, and the confounding effect of spatial variation in fishing effort between seasons, resulting largely from changes in annual ice pattern.