Traditional Owners and area of operation

The Yugul Mangi Land and Sea Management Corporation is based in Ngukurr and work on behalf of traditional owners of the Alawa, Wandarrang, Ritharrngu/Wagilag, Ngandi, Nunggubuyu, Marra, Ngalakgan, Rembarrng and Binbinga peoples whose country is situated in south east Arnhem Land.

The area of operation is approximately 20,000 sq km and includes the Roper River and sea country as far north as Wuyagiba to Limmen Bight in the southern Gulf of Carpentaria. The rangers also work inland as far as Womena.

Landscape description

The country managed by the Yugul Mangi Land and Sea Management Corporation falls within the Gulf Fall and Uplands bioregion (See NRETA 2005). This bioregion is the second largest in the Northern Territory stretching from the Arnhem Land Plateau into western Queensland. It covers some 111,783 sq km of land with some 36% of the bioregion owned by Aboriginal people under the Aboriginal Land Rights (Northern Territory) Act 1976 (ALRA).

The majority of the Yugul Mangi Land and Sea Management Corporation's work in this bioregion occurs in the Roper basin. The major rivers in the Roper Basin include the Roper, Phelp, Wilton, Waterhouse and Hodgson rivers. The Roper River flows from sandstone escarpment country through well defined valleys and sloping coastal alluvial plains into the Gulf of Carpentaria at Port Roper in the Limmen Bight. 

The Roper and the Waterhouse rivers are permanently flowing and retain their Dry season flow from springs associated with groundwater aquifers that cover large areas of the basin. The mouth of the Roper has extensive littoral environment of samphire flats and alluvial sand flats. The lower catchments and floodplains of the Limmen, Towns and Roper rivers and Limmen Bight and islands are recognised as a biodiversity site of national significance. The floodplains and coast are also recognised as wetlands of national importance. They are the second largest area of saline coastal flats in the NT providing habitat to important migratory wading birds in the Dry season. The surrounding waters support significant populations of dugong, and marine turtles. It is also an area of important sea grass habitat (NRETA 2005:135).

The most extensive vegetation in the Gulf Fall and Uplands bioregion is woodland dominated by Darwin Stringybark (Eucalyptus tetrodonta) and Variable-barked bloodwood (Corymbia dichromophloia) with Spinifex understorey and woodland dominated by Northern box (Eucalyptus tectifica) with tussock grass understorey (NRETA 2005:88). The Roper River is unusual for the dense stands of Mataranka palm (Livistona rigida) along the upper reaches, as well as the extensive salt marsh, saline flats and coastal grasslands at the mouth. Patches of monsoon rainforest and vine thicket are found along the rivers, around springs, and on stony slopes protected from fire (NLC 2004).

Ecological threats to this region include weeds, feral animals, wildfires and unregulated use. 'Weeds of National Significance' in Yugul Mangi's area of management include Mimosa (Mimosa pigra), Prickly acacia (Acacia nilotica) and Parkinsonia (Parkonsonia aculeate).

There are significant populations of feral animals in this region. Donkeys, horses, buffalo and pigs are the major species of feral animals. These species contribute to land degradation which is manifested in an increase and dominance of weed species such as Sicklepod (Senna obtusifolia, Senna hirsuta and Senna tora), Sida (Sida cordifolia) and Hyptis (Hyptis sauveolens), and a decline in native species. The feral animals also cause a decline in water quality and the integrity of riparian habitats, threatening both the natural and cultural environment.

In recent times very little has been done to survey the flora and fauna of Aboriginal lands in this area. The status of many species remains unknown. There are at least 24 flora species listed as 'data deficient' (NLC 2004).

Water quality on Aboriginal lands in the management area of Yugul Mangi is generally described as good. Activities of highest impact on water quality are road building increasing silt loads, and trampling and wallowing by feral animals in billabongs and riparian margins of waterways (NLC 2004).

In relation to sea country the Limmen Bight area in general is subject to very high commercial mud-crabbing pressure, although at there is little information available about the local scale ecosystem impacts of this or its impact on Aboriginal customary harvest in the area. Traditional owners have indicated a need to develop a management system for inshore fisheries such as mud crab to enable better spatial management of local impacts and guard against over-fishing at a local scale. There is also concern about the effects of marine debris (such as ghost nets) on marine resources such as turtle and dugong (NLC 2004).