Geographically covering over 100 million square kilometres of the Pacific Ocean, the FFSG Region of Oceania comprises Australia, New Zealand and the 22 Pacific Island countries and territories making up Melanesia, Micronesia and Polynesia. The total human population is estimated at approximately 35 million, of whom nearly two thirds are resident in Australia (IUCN Oceania Office, 2014).
The Pacific Islands region covers almost 15% of the world"s surface and is characterised by a high degree of ecosystem and species diversity as well as an extremely high level of endemicity (often over 90% for particular groups). The region has a high degree of economic and cultural dependence on the natural environment, and many conservation and development challenges: for example, rapid population growth often leading to over-harvesting of natural resources; high levels of threats by invasive species in island ecosystems; and vulnerability to the impacts of climate change (Species Programme, 2014).
Though the entire region is full of diverse wildlife, there is a disproportionate amount of basic data on species. This lack of data, combined with out-of-date information and poorly studied areas means that very little is known about the majority of species in the region (Pippard, 2012). The deficit of information will make it difficult to implement appropriate conservation actions in the region until more is found out about Oceania"s native and endemic species.
The Oceania region has a combined Exclusive Economic Zone of close to 40 million square km. In contrast, the total land area is just over 8.5 million square km, with the larger islands of Australia (7 million square km), Papua New Guinea (463,000 square km) and New Zealand (268,000 square km) accounting for approximately 93% of the total land area.
The human population is estimated at 35 million, with just over 22 million in Australia and 4 million in New Zealand. Approximately 9 million people inhabit the various Pacific Island countries and territories, with differences observed according to the size of the country: for example over 5 million people in the largest land mass of Papua New Guinea and populations under 2,000 in countries such as Niue and Tokelau. The Pitcairn Islands have less than 50 inhabitants. Each year as many as 3 million visitors to the region increase these figures (About Oceania, 2014).
The Pacific Islands are comprised of between 20,000-30,000 islands in the Pacific Ocean, most of which are South of the Tropic of Cancer. The islands of Oceania are categorized as either ‚Äúhigh islands‚Äù or ‚Äúlow islands‚Äù according to their makeup. Volcanoes form high islands, which are typically more fertile and inhabited by more people. The low islands are reefs or atolls and considered less fertile. Most of the freshwater fishes in the region are found in the west Melanesian countries, which are home to more river systems and therefore more freshwater diversity.
Assessments on various freshwater fishes in the Pacific Islands were conducted in 2011 as a joint effort between IUCN Oceania, IUCNs Global Species Programme, and relevant experts, and funded by the Critical Ecosystem Partnership Fund. Data collected were categorized according to criteria of the IUCN Red List of Threatened Species. The Red List is widely recognized as the most comprehensive, objective global approach for evaluating the conservation status of plant and animal species.
The following data and figures are a result of those assessments, bearing in mind that this represents a small proportion of Oceania"s described freshwater fishes. Specifically, much of the research cited below relates to fishes from the Polynesia-Micronesia Biodiversity Hotspot.
The majority of species assessed (91 of 167, or, 53%) were generally widely distributed and did not face any major threats ‚Äì these were therefore classified as Least Concern (LC) According to the IUCN Red List categories and criteria. Due to the lack of information available, a large portion (39%) of the species evaluated were categorized as Data Deficient. The species considered to be threatened (in categories CR, EN and VU) (8%) can be found in the table below.
Figure 1: Threatened freshwater fishes of the Pacific Islands (Pippard, 2012)
It is interesting to note that aside from Neopomacentrus aquadulcis (found in Solomon Islands and Papua New Guinea) all fishes listed as threatened are endemic to a single country. Endemic species and restricted range species are more susceptible to threats than wider-ranging species (Pippard, 2012).
Figure 2: All species assessed by conservation status (Pippard, 2012)
Figure 3: Endemic Species assessed by conservation status (Pippard, 2012)
Though the majority of species live in permanent freshwater rivers or estuarine and mangrove areas, over half of the species assessed in 2011 are migratory and move from freshwater rivers to the sea for spawning.
Freshwater fishes face a host of threats in throughout the whole of the Pacific Islands:
• Over-harvesting. Freshwater fishes are harvested for subsistence or for the aquarium trade. Those harvested for food are often small fry that are on their upstream migration, which can have negative ramifications on populations. Though neither type of harvest mentioned is inherently negative, both actions should be monitored closely in the future.
• Deforestation. This leads to loss of forest cover around rivers and freshwater bodies. Stream morphology changes can affect the life cycles and habitats of many freshwater fish species.
• Coastal Development. Many freshwater fishes of the Pacific Islands reside in or depend on mangrove areas, which are often destroyed for coastal development.
• Agricultural Expansion. The conversion of land for agriculture and farming results in increased river sedimentation. Sedimentation can harm migratory fishes, especially those that rely on clearer water and clean river bottoms for movement.
• Habitat Fragmentation/destruction. The destruction of riverine ecosystems or the fragmentation of habitats affects more than just freshwater species. Fishes, along with other species, require protection and sources of food that are taken away when habitats are destroyed or broken up.
• Invasive Species. Alien (or invasive) species pose a threat most directly to indigenous fish populations. The impacts of invasives in the Pacific Islands is not completely known, and therefore more research is needed on this subject.
• Dams. The presence of dams can interfere with fish passage up and down rivers for migratory species. Dams without fish ladders pose the most obvious threat.
• Climate Change. Island environments are especially affected by climate change. Changes in sea level, for instance, will directly affect freshwater streams and rivers. Mangrove ecosystems and estuaries that serve as a buffer between the rivers and sea will change or disappear as climate change occurs. Salinity levels of freshwater may be especially susceptible to change.
A species" conservation status is one of the most useful signs for assessing the condition of an ecosystem and its biodiversity, and this process would therefore provide much needed baseline data to enable governments, communities and other organizations to implement effective on- the-ground conservation planning and management (Pipppard, 2012). Research is urgently needed before proper conservation actions can be implemented in the Pacific Islands and Oceania. Some recommended conservation actions include:
• Planting of native vegetation adjacent to river systems to combat sedimentation
• Enacting and enforcing pollution laws and agricultural best practices
• Providing the option of fish ladders on all dams, and implementation where appropriate
• Stakeholder education on sustainable harvest levels and conservation techniques
• Preventing the introduction of invasive species in the future, including appropriate legislation
About Oceania (2014). International Union for the Conservation of Nature. http://www.iucn.org/about/union/secretariat/offices/oceania/oro_aboutoceania/
IUCN Oceania Office (2014). International Union for the Conservation of Nature. http://www.iucn.org/about/union/secretariat/offices/oceania/
Pippard, H (2012). The current status and distribution of freshwater fishes, land snails and reptiles in the Pacific Islands of Oceania. Gland, Switzerland: IUCN. 76pp. http://cmsdata.iucn.org/downloads/final_report_1.pdf
Species Programme (2014). International Union for the Conservation of Nature. http://www.iucn.org/about/union/secretariat/offices/oceania/priorities/priority_biodiversity/species2/