The environmental impacts of illegal routes range from an immediate detrimental effect on the target species and incidental loss of non-target species, to a long-term deterioration in ecosystem services with regional and global consequences. Many case studies illustrate various types of environmental impacts, and additionally provide examples of socioeconomic consequences of these impacts, where such information is available.
The most obvious and well-documented environmental impacts of illegal trade in wildlife are the deleterious effects on target species in many cases, declines in wild populations can be directly attributed to illegal harvest and trade, with certain species driven to the brink of local, national, or global extinction as a result.
While there has been much focus on large and charismatic species, illegal trade routes affect a range of other wildlife whose loss may potentially have more notable long-term impacts on the environment, national economies and local livelihoods. Moreover, the environmental consequences of illegal trade routes go beyond the impacts on the target species. Many illegal harvest methods, particularly in the marine environment, have limited or no selectivity and result in substantial incidental mortality of non-target species.
The loss of populations of species as a result of illegal trade routes may have cascading effects across the ecosystem resulting in a deterioration of ecosystem functions and services of national, regional, and global importance. Other environmental impacts of illegal trade routes include the spread of diseases and invasive species.
However, while linkages can be found between illegal trade routes and a wide range of environmental impacts, the relative importance of illegal trade routes as a contributing factor compared to other potential pressures is often difficult to determine and requires further investigation.
The tendency of illegal hunters to target individuals with specific characteristics within a population may have a disproportionate effect in reducing the long-term viability of that population. Various activities associated with illegal trade may increase the risk of disease transmission to wild populations of the target species, in addition to the wider impacts of disease on the environment and human health. The capture and transport of live animals, having less regard for animal welfare where the trade is illegal, may increase the susceptibility of the animals related to disease by placing them under stress and housing them in poor conditions, often found in large numbers. In addition to increasing the risk of mortality of the animals in trade, these diseases may ultimately have detrimental impacts on wild populations, if affected animals are returned to the wild without appropriate screening. In addition to the impacts on the target species of trade, non-target species may also be detrimentally affected by harvesting methods or direct persecution.