Life history traits and conservation actions for the Maugean skate (Dipturus maugeana), an endangered species occupying an anthropogenically impacted estuarine system

AWRUCH C. A.; BELL, J.; SEMMENS, J.; LYLE, J.

AQUATIC CONSERVATION-MARINE AND FRESHWATER ECOSYSTEMS

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2021

1052-7613

1.The Maugean skate, Dipturus maugeana, is endemic to two isolated western Tasmanian (Australia) estuaries. The species persistence in one of these estuaries (Bathurst Harbour) is uncertain, while the other estuary (Macquarie Harbour), potentially the remaining stronghold for the species, is an anthropogenically impacted system. 2.Key life-history parameters were studied to inform conservation actions for this species. Reproductive information was obtained using non-lethal methodologies; circulating concentrations of sex steroids and ultrasonography. Growth and age parameters were estimated based on vertebral sections from a small sample of individuals. 3.Females and males reached 870 mm and 760 mm total length (TL) respectively. The species reached a maximum age of at least 10 years. Females and males attained 50% sexual maturity at 665 and 633 mm TL respectively, likely maturing somewhere between four to six years of age. Females displayed an asynchronous, discontinuous reproductive cycle being able to reproduce throughout the year, with a likely decline in reproductive activity during summer. No egg cases were observed in utero. Males produce sperm all year round, with a peak in testosterone production during spring-autumn. 4.Conservation strategies for D. maugeana will need to focus on reducing anthropogenic impacts on the environmental health, which is linked to altered river flows associated with the production of hydroelectricity and increased nutrient load associated with salmonid aquaculture. There is a need to better understand how reproductive success, egg survival and recruitment are affected by these environmental challenges if the future wellbeing of this unique species is to be secured.