The Committee has discovered many common themes in relation to the utilisation of native plants and animals. Nonetheless there are often differences between sectors and individual ventures that can make generalisation difficult. In this section the nature of these differences and some examples are considered.
The Need for Case-by-case Assessment
The diversity of Victoria's plant and animal species is a reflection of the wide range of environments contained within its relatively small area, from semi-arid shrublands to wet montane forests. Soils vary from alkaline cracking clays to deep acid sands.115 The result is great diversity of vegetation, animals and opportunities for developing new enterprises based on native flora and fauna. At the same time it is important that entrepreneurs understand the conditions in which the species of their choice will thrive and constraints imposed by conditions at any given site. For example yabby farming is largely limited, by temperature and land type, to flat locations with clay soils of low permeability in the west and north of the State.116
One of the consequences of this diversity within Victoria is that generalisations are difficult to make and generalisations are necessary if principles concerning the utilisation of native species are to be developed. Nonetheless, the sustainability of a particular utilisation often depends on particular circumstances of a species, a location or management practices. Both Friends of the Earth and the Australian Conservation Foundation suggested that environmental impact assessment prepared by the proponent could be used to deal with the circumstances of a particular venture.117
The Senate Committee concluded that:
Proposals for the commercial use of wildlife need to be identified and managed on a case-by-case basis. The conditions of commercialisation that are appropriate to each animal must be determined by the biology of the species, a basic knowledge of which should be ascertained prior to commencement of the proposal. Information about the species should include its distribution, abundance and demography. The challenge to achieving sustainability is to provide the necessary broad guidelines while taking adequate account of the specific circumstances of each proposed utilisation.
Kangaroos
Kangaroos, wallabies and possums are harvested from the wild in some States. Proposals have been put forward to hunt wombats and several bird species which are locally in large numbers and may be regarded as pests as well as having commercial value.118 Kangaroo harvesting illustrates some of the issues involved.
The basis of current harvests in other States is often population management of `super-abundant species', that is, species whose numbers have increased locally in response to changes wrought by Western-style agriculture.
Most of the information relating to large kangaroos and their place in managed grazing has been obtained from semi-arid regions. In these regions rainfall is the driving variable. It determines what herbivores have to eat and, in turn, how far they must travel to feed.119 Rangeland grazing is the main farming activity in these regions, with cereal cropping only in the most reliably watered sections.
There are no true rangelands, as defined in the National Rangelands Strategy, in Victoria.120 Only parts of the Mallee resemble the semi-arid regions of South Australia and New South Wales in which kangaroos are harvested, and this land is largely in public ownership or cleared for cropping. As a result, much of the available information can only be related to Victoria with considerable caution.
In some species pregnant kangaroos on very limited feed retain the embryo in a condition of stasis or diapause.121 While feed is in short supply the embryo stops developing. Once conditions improve, growth of the embryo resumes and the mother gives birth at a time when feed is readily available to support the mother and her offspring. Eastern grey kangaroos show limited diapause but western greys show none.122 In times of drought many kangaroos also die of starvation. (In the rangelands a mortality of 50 per cent would be normal during drought.)123 While sheep and some cattle can survive by browsing on native shrubs, many kangaroos will die once grasses and herbs fail. This, in the absence of the introduced species, probably provides an adequate check on kangaroo populations and will maintain a long-term balance between kangaroos and their habitat.124 Where domestic stock and rabbits add to total grazing pressure, large impacts on vegetation may occur unless their numbers are controlled by management.
Death of a proportion of adult kangaroos as a result of adverse conditions or human agency allows more young to be born and survive.125 The result is a change in the age structure of the population. Monitoring of such changes allows for early detection of overharvesting of population. So far there is no evidence that current harvest, based on a quota 10-15 per cent of the population in a region, threatens the conservation of the large kangaroos in the State where they are harvested.126
The issue then becomes one of finding the most effective method to ensure adherence to the quota limit. The current method of annual monitoring populations and allocating quotas on the basis of these numbers incurs the high cost of regular surveys. This is a particularly significant issue for Victoria, where kangaroo densities are low compared with those in neighbouring States.
Integrated Grazing Programs
Proponents of kangaroo harvesting commonly put forward the argument that producing meat and leather from kangaroos is more desirable than from sheep or cattle. The long, soft foot of the kangaroo is far less damaging to native vegetation and soil than the hard hoof of exotic stock. Kangaroos bite off herbage rather than tearing it as do sheep and (to a lesser extent) cattle. This also is less damaging to native vegetation. Unlike sheep, kangaroos also pass most ingested seed intact, providing the basis for future pasture growth.127 A system of mixed production from kangaroos and conventional stock has been advocated as a means of reducing pressure on the land and diversifying farmers' income.128
Representatives of Field and Game Australia and the Sporting Shooters Council of Victoria saw the issue as one of changing landowners' perception of kangaroos from "being a debit to being an asset".129 These organisations argued that allocation to landowners of the ownership rights to kangaroos is the first step in conservation of their habitats. This would encourage landholders to value these animals. A method to do this would be to allocate permits or tags to the landholder to establish his/her ownership. These permits or tags would then be tradable.130
An additional benefit may derive from different dietary preferences of kangaroos and domestic stock. Kangaroos (and wallabies) do not necessarily select the same plants as those eaten by cows and sheep. Studies in the NSW rangelands showed that the diet of the large kangaroos overlapped to only a limited extent with that of sheep during times of plenty.131 It is during drought that there is substantial dietary overlap. Only then is total grazing pressure focussed on the same species.
How well these results can be applied to other regions remains to be seen, but it may be possible to make better use of available feed by utilising the preference of kangaroos and domestic stock for different vegetation.
The Committee recognises, however, that in order to provide a significant incentive for a shift in production to a mixed-grazing system, kangaroos would need to offer returns that are at least comparable with those from sheep or cattle. It is uncertain that they would do so at present.132
Furthermore, the argument for kangaroo harvest in preference to current levels of domestic stock was also made with Australia's rangelands in mind.133 Grazing in these areas is based on native plants that are particularly vulnerable to the harmful effects of hard-hoofed animals. Most of Victoria's grazing occurs on introduced pasture species,134 which are adapted to hard hoofs. 135
There are other barriers to farmers appropriating the resource presented by kangaroos. The range of both individuals and a mob will seldom be confined to an individual property. Individual landholders can do little to husband kangaroos or ensure that they reap benefit from the kangaroos feeding on their land.136 On the other hand, landholders "can appropriate all gains from husbanding domestic livestock and can expand the number of these whenever this is profitable, even if the increase in profit [to the individual farmer] is less than the loss in collective profit from kangaroos".137 A cooperative approach would be needed for farmers to gain the best returns from kangaroos.
Trade Between Zoos
There is considerable demand for native animals for zoos, wildlife sanctuaries and nature parks, both within Australia and overseas.138 The suitability of animals and motivation for using them in this way varies.
Motivation may be essentially commercial or include primary objectives of public benefit through education and conservation of endangered species.139 Ventures that are essentially commercial may also achieve public education and conservation objectives as by-products of their commercial imperatives.
Endangered species may be kept and bred in captivity to ensure the survival of the species. For example the government of Western Australia sells endangered species to zoos.140 Ideally conservation of a rare species will be concentrated on protection and restoration of its habitat. This will conserve its natural genetic character and behaviour as well as the species per se. Captive breeding can be expected to alter both genetic composition and behaviour.141 However, when a species is very rare and there is little chance of its recovery in the wild, captive breeding may be the only way to ensure that it does not become extinct.
The suitability of animals for use in captive displays and education programs varies with species. Some, like platypus, are highly sensitive to stress.142 These are not regarded as appropriate for any but the most carefully designed display.
One criterion which is used to assess the suitability of a species for uses that require captivity is its capacity to be bred in captivity. Unless it will regularly breed, its ability to adapt adequately to captivity must be questioned. Certainly such a species is likely to experience severe stress during capture and relocation. This is the view held by the Zoological Parks and Gardens Board of Victoria (ZPGBV) and is one of the reasons why the Board has so far refused to export platypus to overseas zoological parks.143
The suitability of a species for use as part of a captive display depends, in part, on the conditions under which it will be kept as well as transported. It is probable that greater control over these conditions can be provided within Australia than for exported animals. Matching conditions of transport and captivity to the known needs of the species could increase the number of species accepted as candidates for live trade.
As with the platypus, rarity (or absence) of a species in captivity may ensure that it will command a high price on an overseas market.144 This same rarity may well reflect the vulnerability of the species to transport and confinement, except under conditions that very closely resemble its natural environment. Unless such conditions can be assured, the species would appear to be ill suited to export.
The ZPGBV, with other leading Australian zoos and sanctuaries, does not sell or trade animals from its zoos.145 The primary object of moving animals through the worldwide network of zoos is to maintain the genetic integrity of populations. The Board donates and lends animals to zoos that it considers to be of a sufficient standard. It has an accreditation program and only deals with zoos that meet these standards. When animals are given or lent to overseas zoos, staff of the Board travel with the animals and stay with them until they are established in their new location.
Tree-fern Harvesting
In Victoria the soft tree fern (Dicksonia antarctica) is harvested under permit for use in ornamental horticulture. This species is suitable for wild-harvest as it will establish readily in damp soil from a section including part of the trunk and the fronds. The more hardy rough tree fern (Cyathea australis), though better suited to most gardens, cannot be relocated in this way. It can only be established readily from spores.146 Both species are commercially cultivated and sold in domestic and export markets, and are common and popular garden plants. They are also commercially propagated. However, the majority of ferns sold in Victoria are wild-harvested soft tree ferns.147
The Committee was informed that, while the utilisation of tree ferns is heavily regulated on private land, thousands are bulldozed then burnt during tree clear-felling operations in State forests.148 Tree-fern operators, rather than see a valuable resource `wasted', would like to harvest tree ferns before logging operations commence.149
During a clear-felling operation, undergrowth, including tree ferns, is bulldozed to allow access to the trees. Once trees have been felled and removed, the bulldozed undergrowth (which can be up to 6 metres deep across the felling site) is either left where it lies, for subsequent burning, or is bulldozed into windrows and burnt.150 The purpose of clear-felling, rather than selective logging, is to mimic the destruction of the canopy and the understorey that occurs during infrequent wildfires. This allows the regeneration by removing most shade and release of nutrients.151 However, there is commonly a decline in understorey species, such as tree ferns, that normally resprout from vegetative parts after fire.152 These species are frequently damaged or destroyed during mechanical clearing. Other species, which need the shade provided by tree ferns to re-establish, are also disadvantaged.
Not all ferns die as a result of clear-fell logging operations and subsequent regeneration burning.153 It is estimated that 15 per cent of tree ferns survive on a clear-felled site, although further mortalities occur over subsequent years.154 Surviving tree ferns are considered to be an essential component of the recovery of the ecosystem, which is already under some stress as a result of the logging operation.
Current government policy is based on the belief that, if harvesting of tree ferns were permitted prior to logging, the combined operations would lead to a decreased survival rate of tree ferns in logging coupes. The survival of a number of upright tree ferns on a clear-felled site is essential to the recovery of the ecosystem.155
The Committee notes that the DNRE has conducted research in the Victorian central highlands on partitioning logging coupes into different sections; a large area (92-98 per cent of the total coupe area) in which mechanical disturbance occurs; and other small areas set aside as machinery-free areas. The latter are referred to as understorey islands.156 The study found that in understorey islands 69 per cent of the tree ferns survived after timber harvesting.157 Tree-fern harvesting could possibly occur in the areas that are to be bulldozed while avoiding the understorey `islands' if adequate area were to be set aside as islands. Although tree-fern survival on the cleared area would be reduced (possibly to zero) under the combined operations of harvesting and logging, survival over the entire coupe may be adequate to retain the integrity of the forest ecosystem, due to the presence of the understorey islands. What proportion of the coupe would need to be retained as islands and their desirable configuration would need to be determined. Certainly, based on research by the DNRE, it is likely to be more than 10 per cent and may be greater than 15 per cent.158
