Distribution, reproduction and population structure of three gulper sharks (Centrophorus, Centrophoridae) in south-east Australian waters
Published on 24 June 2011
K. J. Graham and R. K. Daley.
ABSTRACT:
Gulper sharks (Centrophorus spp.) are commercially fished in all oceans but the taxonomy and biology of many species are not clearly defined, and stocks are extremely vulnerable to over-exploitation. We present distributional, size-frequency and reproductive data for three species (Centrophorus harrissoni, C. moluccensis and C. zeehaani) that fishing has largely extirpated from the south-east Australian upper continental slope. Trawl-survey catches in 1976–77 from lightly exploited stocks comprised mostly mature males with few mature females or juveniles; a 2009 long-line survey caught higher proportions of mature females and, for C. harrissoni, more juveniles. Females of the three species grew larger and reached maturity at a greater size than males and, for both sexes, maturity sizes were more than 80% of their maximum observed lengths. Reproduction was continuous but data were insufficient to determine seasonality. Ovarian and uterine fecundity were singular for C. zeehaani whereas C. harrissoni and C. moluccensis developed two oocytes and produced one or two embryos; evidence suggests that the left-side uterus is less functional than the right-side. In response to these species’ inherent low productivity and continuing reduced numbers, managers have introduced landing restrictions and area closures to enhance Centrophorus stocks in southern Australian waters.
Marine and Freshwater Research 62(6) 583-595 http://dx.doi.org/10.1071/MF10158