6.7 Aquatic species diversity
There have been no new extinctions of aquatic species in NSW in recent years, but the listings of threatened species has increased
Aquatic species diversity in NSW remains under threat. Knowledge about the scale of the problem is growing with better processes in place for recognising and assessing at-risk species and communities. No additional species have been presumed to be extinct since State of the Environment 2000, but there have been seven new listings of threatened species, populations and communities.
Recovery planning for threatened species is behind schedule and is not keeping up with the increase in listings of vulnerable and endangered species and communities.
NSW Indicators
Indicator |
Status of Indicator |
6.12 Number of aquatic extinct, endangered and vulnerable species, populations and ecological communities |
The number of species, populations and ecological communities being listed as endangered or vulnerable is increasing, but no new extinctions have been identified since State of the Environment 2000. |
6.13 Number of aquatic recovery plans |
Recovery planning is behind schedule. |
Importance of the issue
Aquatic species play a crucial role in maintaining ecological processes. Loss of species diversity weakens essential natural ecosystems and diminishes available ecosystem services, which can have significant ecological, economic and social impacts.
The NSW Rivers Survey examined freshwater fish communities across NSW over a two-year period in the mid-1990s (Harris & Gehrke 1997). The survey concluded that there has been a decline in the biodiversity of the State's riverine ecosystems. The decline was particularly apparent in the Murray region; in upland areas; in inland lowland rivers; and in rivers that are regulated for water supply. Nearly 30% of the 55 species of native freshwater fish in NSW have not been observed in recent surveys (Harris & Gehrke 1997; NSW Fisheries 2000).
The distribution of some species that were previously common across NSW is now restricted. These include the olive perchlet, freshwater catfish, short-finned eels and river blackfish. Other species, such as the spangled perch and shortheaded lamprey, have recently been found outside their usual habitats. Physical abnormalities and deformities were also recorded during the survey, with up to 25% of fish showing evidence of parasites and disease.
The health of freshwater riverine ecosystems in NSW has also been assessed using macroinvertebrates through the National River Health Program (see Water 5.1).
The diversity of bird populations is a useful indicator of biodiversity because of birds' sensitivity to environmental changes. Habitat loss and degradation and changes to water supply are the greatest threats to waterbird populations in Australia (Kingsford & Norman 2002). For example, the breeding of some waterbirds, such as ibis, egrets and herons, has been affected by the construction of dams and diversion of water in the Macquarie Marshes and the Barmah–Millewa Forest (Kingsford & Johnson 1998; Leslie 2001). In general, deep artificial reservoirs have less diverse waterbird populations than natural (and usually shallower) wetlands and lakes. Reductions in the size of floods in wetlands and their frequency have also affected many waterbird species (Kingsford & Norman 2002).
Response to the issue
Biodiversity 6.6 discusses broad responses to aquatic ecosystem decline. Additional responses to deal specifically with difficulties faced by certain aquatic species and ecological communities include listing threatened aquatic species and threatening processes, and managing them through aquatic recovery and threat abatement plans.
The Fisheries Management Act 1994 (FM Act) aims to protect all threatened fish and marine plant and algal species native to NSW waters. The Act provides for the official listing of extinct, endangered and vulnerable fish, including molluscs, crustaceans and other invertebrates, and marine vegetation.
Around 16% of the State's vertebrate freshwater fish species are listed as threatened compared with less than 1% of marine vertebrate fishes. This may be because freshwater habitats have been more highly modified by human activities than most marine environments. Freshwater invertebrates have not been well documented and are probably under-represented in threatened species listings.
Other aquatic fauna, including marine mammals (such as whales and seals), amphibians, reptiles and birds, are protected under the Threatened Species Conservation Act 1995 (TSC Act).
The FM Act also provides for the identification and listing of key threatening processes for species, populations and communities. At June 2003, two aquatic endangered ecological communities and four key threatening processes had been listed, while 'alteration of flows' was declared a key threatening process under both the FM Act and TSC Act.
The addition of an aquatic component to the NSW Biodiversity Strategy will provide specific objectives, performance targets and actions for the conservation of fish, aquatic invertebrates and marine vegetation. This will be in addition to actions related to those components of aquatic biodiversity currently covered by the TSC Act, including freshwater vegetation, amphibians, turtles, tortoises, sea snakes, waterbirds and aquatic mammals.
Fish Habitat Protection Plans also provide protection for specific aquatic habitats. Public authorities need to take into account any plans in force during decision-making. Three of these plans have been completed: one overarching plan, another for a specific area (the Hawkesbury–Nepean river system), and the third covering an ecosystem type (seagrasses).
Aquatic recovery and threat abatement plans
A recovery plan is required for each species listed as threatened under the FM Act. Table 6.10 shows the number of recovery plans required and approved.
Table 6.10: NSW aquatic recovery plans
|
Number of plans (FM Act only) |
Change since SoE 2000 |
Recovery plans required(a) |
18 |
+ 7 |
Recovery plans approved |
0 |
0 |
Source: NSW Fisheries data, as at June 2003
Note: (a) Excludes species presumed extinct
Two draft recovery plans have been developed for the eastern (freshwater) cod (Maccullochella ikei) and the grey nurse shark (Carcharias taurus). A draft recovery plan for the Oxleyan pygmy perch (Nannoperca oxleyana) is in the final stages of preparation. Work is also well advanced on draft recovery plans for the trout cod (Maccullochella macquariensis) and the green sawfish (Pristis zijsron).
Recovery planning processes are also under way for four whale species (blue, southern right, humpback and sperm) which are listed as threatened under the TSC Act. Recovery action to date for these species has included survey work on their numbers and distribution (NPWS 2000).
Threat abatement plans are currently required for four key threatening processes listed in the TSC Act. A draft plan for mosquito fish (Gambusia holbrooki) has been submitted for approval after being exhibited publicly.
In addition to formal recovery planning, a number of recovery actions are under way for listed threatened species. These include research and compliance work, and conservation stocking programs for the trout cod and eastern cod. There have also been several assessments of the conservation status of fish species:
- Morris et al. 2001 reviewed the basic biology, distribution and conservation status of 30 coastal and Murray–Darling species under threat
- Pogonoski et al. 2002 assessed the status of over 50 marine and estuarine fish species found in NSW waters.
Effectiveness of responses
Monitoring of aquatic species diversity is difficult and data is not available to assess the effectiveness of responses to declining diversity.
The revised NSW Biodiversity Strategy will outline areas where further action is required to assist the conservation of aquatic biodiversity. These could include threatening processes and their management; conservation of important biodiversity components; integrating biodiversity conservation within natural resource management frameworks; improving knowledge; and community consultation, involvement and ownership.
Future directions
The Government needs to complete recovery plans and threat abatement plans for listed aquatic species.
It could also expand the fish habitat protection planning process and continue controls on development proposals that may lead to the loss, depletion or degradation of aquatic habitat, species or communities.
Government and stakeholders must find new models of working together to achieve results that enhance the protection of aquatic species and restoration of habitats with a fair sharing of costs.
Linked issues
2.1 Population and settlement patterns
3.2 Climate change
4.1 Land-use changes
4.2 Soil erosion
4.3 Induced soil salinity
5.1 Freshwater riverine ecosystem health
5.2 Surface water extraction
5.3 Surface water quality
6.6 Aquatic ecosystems
6.8 Introduced aquatic species
6.9 Aquatic harvesting
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