Biosecurity and pathways into Aotearoa New Zealand: relating biosecurity detections to tourism

International trade and tourism, while essential to the world’s economy, has also been implicated as facilitating the dispersal of exotic species. Tourism, in its broadest sense, can provide significant economic gain to a country’s GDP, but if not managed carefully then economic, social, cultural and environmental costs may arise. From a biosecurity perspective, the sometimes massive and rapid movement of people associated with international tourism has been implicated in the dispersal of exotic organisms both across and within countries, some of which become invasive. Although between-country tourism is established as a facilitator of the spread of invasive alien species, little attention has been paid to the question of whether tourism contributes to the arrival and subsequent dispersal of exotic organisms within national borders. To assess the strength of evidence that tourism is a driver for the accidental introducing and dispersal of exotic organisms, we sourced three national databases covering the years 2011 to 2017, namely (i) international and domestic hotel guest nights, (ii) national population counts, and (iii) records of exotic organism detections collected by the Ministry for Primary Industries, which is the New Zealand government agency that oversees biosecurity. The exotic organisms database comprised records of insects, Arachnid spp. (spiders and mites), snails, plants (terrestrial and aquatic), nematodes and microbes (bacteria, fungi and viruses) that were detected post border. We fitted statistical models to assess the strength of relationship between monthly exotic organism interception rate, guest nights and population, the latter as a baseline. The analysis showed that levels of incursion detection were significantly positively related to tourism records (P = 0.00078), reflecting the travel of both international and domestic tourists, even when base population was taken into account. There was also a significant positive statistical correlation between the levels of detection of exotic organisms and human population (P = 0.0046). The number of nights duration spent in specific accommodation, which is a key indicator of within-country human population movement, is statistically significantly correlated to the contemporaneous detection of exotic pests. In each case the amount of variation explained was small. We conclude that this study provides evidence of impact of within-country movement upon the internal spread of invasive species, although important caveats need to be considered. The results also reinforce the need for biosecurity authorities to continue to allocate resources to managing the tourism pathway.