Newly established invasive alien species indicator: data sources and methods, chapter 5


5. Caveats and limitations

The indicator includes species that are discovered during normal business and determined to have established since the baseline year. In general, active field searches for new invasive alien species are not made although surveillance is undertaken for some species.

Regulated refers only to federal regulations and federal regulatory status.

Newly detected species may be subject to an eradication effort. These species are not deemed to have become established unless eradication has failed and efforts have been abandoned.

Alien species may be present without becoming invasive, and it may take some time to recognize whether a species is invasive. The establishment date of a species may be difficult to determine, particularly if an invasion was not detected early. Range extensions of species native to the United States would not normally be considered an invasion.

While invasive alien species can also affect human health, the human health dimension is largely covered under existing human health programs and is excluded from the scope of An Invasive Alien Species Strategy for Canada, and thus from this indicator.

Comparisons to other data sources should be made with caution. In particular, counts may not match other sources because related species may be regulated as a group, because some members of a group may be established while others are not, and because species may be regulated under more than one piece of legislation.

Species that are native to a region in Canada that are invading elsewhere in Canada are not included, even if these species are federally regulated.

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