This Conservation Advice was approved by the Minister / Delegate of the Minister on: 3/7/2008 Approved Conservation Advice (s266B of the Environment Protection and Biodiversity Conservation Act 1999) Approved Conservation Advice for Raja sp. L (Maugean Skate)
This Conservation Advice has been developed based on the best available information at the time this conservation advice was approved.
Description
Raja sp. L, Family Rajidae, now known as Zearaja maugeana, also known as the Maugean Skate or Port Davey Skate, is a medium-sized primitive skate. It is dark brown above and dark with dark-edged pores beneath. Males reach a maximum size of 70 cm, females 84 cm. The Maugean Skate is the only skate known to inhabit brackish water (Agbayani, 2001; Last & Gledhill, 2007).
Conservation Status The Maugean Skate is listed as endangered. This species is eligible for listing as endangered under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC Act) as, in 2004, the Minister considered the Threatened Species Scientific Committee’s (TSSC) advice under section 189 of the EPBC Act and amended the list under section 184 to include Raja sp. L. The TSSC determined that this species met Criteria 2 and 3 of their eligibility criteria (TSSC, 2006b). The Maugean Skate is also listed as endangered under the Threatened Species Protection Act 1995 (Tasmania).
Distribution and Habitat The Maugean Skate inhabits two small estuarine systems, in Macquarie Harbour and Bathurst Harbour, in southwest Tasmania. The total range of the species is thought to be no more than 100 km² and the population is estimated at 1000 individuals (TSSC, 2004). Maugean Skates inhabiting the two estuaries may comprise two separate populations (IUCN, 2007). The species inhabits low-nutrient brackish water, 5–7 metres deep (TSSC, 2004). Maugean Skates appear to mostly inhabit the shallower upper regions of the estuaries (IUCN, 2007). This species occurs within the North West and South (Tasmania) Natural Resource Management Regions. The distribution of the Maugean Skate is not known to overlap with any EPBC Act-listed threatened ecological communities.
Threats The main potential threats to the Maugean Skate are trace metal pollution from historic mining operations in Macquarie Harbour; incidental capture in fishing activities; the introduction of non-native marine species; changes to the water nutrient levels through discharge from cruise ships and fishing vessels; and an increase in tourism pressure in these areas.
Research Priorities Research priorities that would inform future regional and local priority actions include: • Design and implement a monitoring program. • More precisely assess population size, distribution, ecological requirements and the relative impacts of threatening processes. • Undertake survey work in suitable habitat and potential habitat to locate any additional populations/occurrences/remnants. Raja sp. L Conservation Advice - Page 1 of 2 This Conservation Advice was approved by the Minister / Delegate of the Minister on: 3/7/2008 Regional and Local Priority Actions The following priority recovery and threat abatement actions can be done to support the recovery of Maugean Skate. Habitat Loss, Disturbance and Modification • Monitor known populations to identify key threats. • Monitor the progress of recovery, including the effectiveness of management actions and the need to adapt them if necessary. • Manage threats to harbours and associated estuaries that contain populations of Maugean Skate. • Ensure harbour and estuary maintenance activities (or other infrastructure or development activities) in areas where Maugean Skate occurs do not adversely impact on known populations. • Minimise adverse impacts from harbour and estuary use at known sites. • Manage any changes to hydrology that may result in changes to the water table levels, increased run-off, sedimentation or pollution. • Manage any disruptions to water flows. • Investigate suitability of designating habitat areas as Marine Protected Areas (TSSC, 2004). • Suitably control and manage ecotourism in the area. Animal Predation or Competition • Develop and implement a management plan for the control and eradication of introduced marine species in the local region. • Implement a management plan to prevent introduction of marine species to the harbour from cruise ships and fishing vessels. Conservation Information • Raise awareness of the Maugean Skate within the local community, especially with regards to commercial and recreational fishing. Enable Recovery of Additional Sites and/or Populations • Investigate options for enhancing or establishing additional populations.
This list does not necessarily encompass all actions that may be of benefit to the Maugean Skate, but highlights those that are considered to be of highest priority at the time of preparing the conservation advice.
Information Sources: Agbayani, E 2001, Zearaja maugeana, viewed 10 April 08,
Raja sp. L Conservation Advice - Page 2 of 2