The purpose of this study is to review theoretical and empirical findings in economics with respect to the challenging question of how to manage invasive species. The review revealed a relatively large body of literature on the assessment of damage costs of invasive species; single species and groups of species at different geographical scales. However, the estimated damage costs show large variation, from less than 1 million USD to costs corresponding to 12% of gross domestic product, depending on the methods employed, geographical scale, and scope with respect to inclusion of different species. Decisions regarding optimal management strategies, when to act in the invasion chain and which policy to choose, have received much less attention in earlier years, but have been subject to increasing research during the last decade. More difficult, but also more relevant policy issues have been raised, which concern the targeting in time and space of strategies under conditions of uncertainty. In particular, the weighting of costs and benefits from early detection and mitigation against the uncertain avoidance of damage with later control, when the precision in targeting species is typically greater is identified as a key challenge. The role of improved monitoring for detecting species and their spread and damage has been emphasized, but questions remain on how to achieve this in practice. This is in contrast to the relatively large body of literature on policies for mitigating dispersal by trade, which is regarded as one of the most important vectors for the spread of invasive species. On the other hand, the literature on how to mitigate established species, by control or adaptation, is much more scant. Studies evaluating causes for success or failure of policies against invasive in practice are in principal non-existing.

The purpose of this paper is to present calculations of total costs of 13 alien invasive species (AIS) in Sweden. All species are subject to control by Swedish public authorities, and estimates for most AIS include either damage cost or actual control cost. The results indicate a total annual cost between approximately 1620 and 5080 million SEK, which correspond to SEK 175 and SEK 565 per capita in Sweden. The estimates are well within the range of similar calculations for other countries, but differ with respect to the composition of costs of different AIS. Whereas costs for the agricultural and forestry sectors dominate in most other studies, the costs of AIS in Sweden are more equally divided among different categories. The results also indicate that the highest costs are attributable to unintentionally introduced AIS and that the most reliable cost estimates are related to human and animal health.

This study makes an explorative overview on two main research topics in economics of wildlife management: determination of population sizes and policy design. The results point out a large and comprehensive research on each of these issues, in particular on the estimation of values and costs of wildlife, where this information is necessary for the determination of population size. A drawback is that most of the value and cost studies do not relate their estimates to wildlife population size, which limits their usability for efficient policy design. Most valuation studies estimate the recreational value of hunting, which can range between 13 and 545 USD/hunting day (in 2013 prices), and two thirds of the included studies have been applied to wildlife in the USA. A majority of the studies on the costs of wildlife management calculate losses from carnivore predation on livestock and ungulate damage to crops, while a few consider dispersal of diseases and the cost of traffic collisions. Unlike valuation studies, several of the cost estimates apply to wildlife in developing and emerging economies. With respect to policy design the literature, which is mainly theoretical, suggests economic incentives for conflict resolution, where those suffering from wildlife damages are compensated for their losses. However, there are some issues which remain to be addressed by economists: relating costs and benefits to wildlife populations; estimating values and costs of wildlife in developing countries; evaluating wildlife policies in practice; addressing implications of uncertainty in population size, costs, and benefits for policy design; and estimating transaction costs for implementation and enforcement of wildlife policies.