Construction and application of risk assessment system for the introduction of exotic aquatic animals

The aquatic ecosystem is an important part of the earth's environment, and a healthy aquatic ecological environment is an important prerequisite for aquatic ecosystems to provide services and perform their functions, as well as a solid guarantee for the healthy development of modern aquaculture. However, in recent decades, biological invasions of exotic aquatic animals are considered to be a major driving factor in the vanishing of biodiversity in many aquatic ecosystems in China. Some exotic aquatic species have even caused irreversible damage to some of China's aquatic ecosystems, with far-reaching hazards and adverse effects. In the past two decades, with the development in ecology, environmental science and other related disciplines, Chinese researchers have conducted increasingly in-depth research on invasive alien species (IAS). Through extensive analysis of the biological characteristics of invasive alien species and their invasion process and mode, it is found that apart from a few exceptions, biological invasion around the world are almost all caused by the active and passive diffusion of alien species caused by human activities. Among the many factors of alien species diffusion, the introduction and artificial breeding of alien species with economic and trade as the core purpose is one of the important factors, which includes not only the biological invasion caused by alien species themselves, but also the impact of pathogenic organisms carried by alien species on local species, ecological environment, the enormous threat posed to human health and other factors. Internationally, many countries regard the risk assessment of invasive alien species as an important measure for solving the problem of biological invasion. Conducting risk assessments of invasive alien species and formulating more scientific introduction policies and programs on the basis of the assessment results can effectively reduce the obstacles to aquaculture development and economic losses caused by biological invasions and other issues. However, the risk assessment methods currently adopted by most countries in the world are qualitative or semi-quantitative, and with regard to the accuracy of results, there is a significant gap between qualitative and quantitative assessments. Moreover, due to the large differences between terrestrial ecosystems and aquatic ecosystems, there are differences between terrestrial animals and aquatic animal in the process and mechanism of biological invasions. Most risk assessment systems are developed for terrestrial animals, and the adaptability between these risk assessment systems for terrestrial animals and aquatic animal is low, while the existing research and development of aquatic animal assessment systems are still relatively rudimentary. To further refine the research in related fields, this study took exotic aquatic animals as the main research object, analyzed the possible ecological risks and invasion mechanisms of common exotic aquatic animals, and used analytical hierarchy process (AHP) to construct a risk assessment system for the introduction of exotic aquatic animals. This risk assessment system consists of six primary indices (exotic species characterization, ecological risk assessment, pathogen entrance, pathogen exposure, hazard and impact, and exotic species risk prevention and control) and thirty-two secondary indices. Then, it was used to conduct quantitative risk assessments on three typical exotic aquatic animals in China. The assessment results show that the risk value (R) of Atractosteus spatula was 3.948 6 and the risk grade was high, strict introduction strategies and risk prevention measures needed to be formulated, and standardized introduction should be carried out in close communication with relevant departments such as customs. The R of Mizuhopecten yessoensis was 2.908 1, which means the risk grade was medium and it needed to be introduced with restrictions under strict management by customs and relevant departments. The R of Panulirus ornatus was 1.868 8 and its risk grade was low, indicating that it could be introduced if allowed by national policies. The assessment results were highly consistent with the information provided by relevant units such as the Ministry of Agriculture and Rural Affairs, the Ministry of Ecology and Environment, and the General Administration of Customs in China, proving that this risk assessment system has important application value in the risk assessment of the exotic aquatic animals’ introduction. Concurrently, quantitative risk assessment of exotic aquatic animals through the risk assessment system can provide theoretical support for scientific introduction and healthy farming effectively and accurately, and provide decision-making basis for risk management of exotic species.