Ecology and Management of Invasive Alien Species: Management

Early detection of non-indigenous species should be based on a system of regular surveys to find newly established species. However, not all species will become established, and only a small percentage of those that do will become invasive, presenting threats to biodiversity and the economy. Thus, some surveys will need to focus on specific target species known to be invasive under similar conditions or species that have been successfully eradicated before. Methods to detect species differ between taxonomic groups, and their success depends largely on taxonomic difficulties and how conspicuous species are. Sampling techniques are discussed for the major taxonomic groups. In addition, site-specific surveys looking for alien species in general can be carried out. They should be targeted at key sites, e.g. areas of high conservation value, within the range of highly endangered species, and at high-risk entry points such as airports and harbours. The drawback of these general surveys is that only well-trained staff will be able to identify non-indigenous species in many taxonomic groups.

Staff responsible for the surveys needs to be trained. Public education should focus on groups using or acquainted with the natural environment, such as farmers, tour operators, and the concerned public. This education campaign can be based on media promotion, displays, and personal interactions. The training of survey staff must include development of taxonomic knowledge, use of databases and identification services, and survey methods for the different groups. The training could be either in-country, with or without overseas experts, or in courses held abroad.

A crucial part of early detection is a contingency plan, which determines the action to be taken when an alien species is been found. Given the diversity of potential new incursions, an initial plan will be rather general. It should summarize the stakeholders and experts who need to be contacted for a more detailed action plan. Contingency plans targeted at specific high-risk species can be very efficient, with an exact schedule for what to do. For a contingency plan to work, the equipment needed must be in perfect condition and at the designated place. The relevant government departments responsible for bioinvasions should make contingency funding available for emergency eradication or control.

Once an alien species is present in a new country, there will be a brief period when its chances of establishment will hang in the balance. However, the longer it goes undetected at this stage, the less opportunity there will be to intervene, the fewer options will remain for its control or eradication, and the more expensive any intervention will become. For example, eradication will rapidly cease to be an option the longer an alien is left to reproduce and disperse. Not all alien species will necessarily become invasive, so species known to be invasive elsewhere, especially those spreading within a region, should be priorities for early detection. The possibility of early eradication or getting a new colonizer under effective early control makes investment in early detection worthwhile.

A series of steps are involved in the early detection of invasive species. These include:

1.  Surveys

• General surveys

• Site specific surveys

• Species specific surveys

• Data collection and storage

2.  Developing a corps of experts/trainers

• Who to train

• Training needs

• Where to train

• Who will do the training

• Staff retention

3.  Contingency plans and funding

• Costs of contingency plans