Search the SPREP Catalogue

The introduction and spread of non-indigenous marine species to Pacific Island countries and territories is a threat to biodiversity, commerce, and socio-cultural values. Yet, little is known about what marine non-indigenous species (NIS) are present throughout the Pacific Island region or what their impacts are. We define here an invasive species as an NIS if (i) the species has demonstrated impact anywhere outside its indigenous range, (ii) the species is widespread, abundant, fast-spreading or has a high population growth rate anywhere outside its indigenous range, or (iii) the species is widespread, abundant, fast spreading or has a high population growth rate in the reporting country (McGeoch et al. 2012). Not all NIS are considered harmful or “invasive”.

Biodiversity on marine islands is characterized by unique biogeographic. phylogenetic and functional characteristics. Island hold a disproportionate amount of the world's biodiversity, and they have also experienced a disproportionate loss of it.

The three most invasive rat species, black or ship rat Rattus rattus, brown or Norway rats, R. norvegicus and Pacific rat, R. exulans have been incrementally introduced to islands as humans have explored the world’s oceans. They have caused serious deleterious effects through predation and competition, and extinction of many species on tropical islands, many of which are biodiversity hotspots. All three rat species are found in virtually all habitat types, including mangrove and arid shrub land. Black rats tend to dominate the literature but despite this the population biology of invasive rats, particularly Norway rats, is poorly researched on tropical islands. Pacific rats can often exceed population densities of well over 100 rats ha?1 and black rats can attain densities of 119 rats ha?1, which is much higher than recorded on most temperate islands. High densities are possibly due to high recruitment of young although the data to support this are limited. The generally aseasonally warm climate can lead to year-round breeding but can be restricted by either density-dependent effects interacting with resource constraints often due to aridity. Apparent adverse impacts on birds have been well recorded and almost all tropical seabirds and land birds can be affected by rats. On the Pacific islands, black rats have added to declines and extinctions of land birds caused initially by Pacific rats. Rats have likely caused unrecorded extinctions of native species on tropical islands. Further research required on invasive rats on tropical islands includes the drivers of population growth and carrying capacities that result in high densities and how these differ to temperate islands, habitat use of rats in tropical vegetation types and interactions with other tropical species, particularly the reptiles and invertebrates, including crustaceans.

Lying about three-quarters of the way from Hawaii to Australia, Vanuatu represents the main bulk of an island chain which continues into the eastern Solomon Islands. The islands are volcanic rock or uplifted carbonate structures and there is ongoing volcanic activity in a number of locations. Fringing reefs predominate. Crown-of-thorns sea star (Acanthaster planci) outbreaks have been reported. Up to the present time the larger islands have remained forested, however, increased logging threatens to destroy Vanuatu’s rainforests. Rising pollution from sewage inputs and sediment run off and overharvesting of some non-motile reef species are also concerns.

Situated between Fiji to the west and Samoa to the northeast, the Kingdom of Tonga (referred to as Tonga) is comprised of 171 scattered islands of which less than 50 are inhabited. The islands are mainly composed of limestone formed from uplifted coral. Current critical environmental concerns have arisen due to deforestation; damage to coral reefs and the introduction and spread of invasive alien species. Anthropogenic pressure has resulted in extensive modification of all ecosystems on the limestone islands of this group. Only uninhabited and steep volcanic islands still support large tracts of forest.

A Global Environment Facility (GEF) funded project is currently being implemented in the Republic of the Marshall Islands (RMI) titled the “Prevention, Control and Management of Invasive Alien Species in the Pacific Islands”. This is a multicountry project and includes Niue, Federated States of Micronesia, Cook Islands, Papua New Guinea, Palau, Kiribati, Tonga, Samoa and Vanuatu. Activities within the framework of this project include the conservation of priority species and ecosystems and the management of invasive alien species (IAS). Please see Table 1 below for list of key deliverables identified by the Government of RMI.

A Global Environment Facility (GEF) funded project is currently being implemented in Niue titled the “Prevention, Control and Management of Invasive Alien Species in the Pacific Islands”. This is a multicountry project and includes the Cook Islands, Federated States of Micronesia, Kiribati, Marshall Islands, Niue, Papua New Guinea, Palau, Tonga, and Samoa. Activities within the framework of this project include the conservation of priority species and ecosystems and the management of Invasive Alien Species (IAS).

A Global Environment Facility (GEF) funded project is currently being implemented in the Federated States of Micronesia (FSM) titled the “Prevention, Control and Management of Invasive Alien Species in the Pacific Islands”. This is a multicountry project and includes the Niue, Cook Islands, Marshall Islands, Papua New Guinea, Palau, Tonga, Kiribati, Samoa and Vanuatu. Activities within the framework of this project include the conservation of priority species and ecosystems and the management of invasive alien species. Please see Table 1 below for list of key deliverables identified by the Government of the FSM