Ecological and Economic Impacts and Invasion Management Strategies for the European Green Crab
The goals of this case study were to estimate the European green crab’s current and historical impacts on ecosystem services on the East Coast of the United States and to estimate the European green crab’s current and potential future impacts on ecosystem services on the West Coast of the United States under various invasion scenarios. The study revealed significant data limitations that rendered benefit cost analysis of green crab control programs not feasible. Specifically, there is no information on green crab population changes due to various management and control strategies. Nevertheless, the comparison of the estimated damages from green crab predation and the expenditures on green crab control suggests that development and implementation of such programs may benefit local economies (assuming that these programs are effective).
The estimated total losses from green crab predation to commercial and recreational shellfisheries and eelgrass restoration efforts range from $18.6 to $22.6 million per year (see Table 8-1). We note that these estimates do not account for damages caused by the green crab to a number of species such as oysters, winter flounder, and non-shellfish benthic populations as well as non-use values of the species included in the analysis. This analysis could be potentially expanded to include winter flounder and benthic populations. In addition, these estimates do not account for changes in the overall health of ecosystems invaded by green crabs and the associated change in the value of these ecosystems. In comparison, the estimated public expenditures for green crab management are only $315,000 for years 2007–2010. As noted in Section 7-4, this estimate may significantly under-represent the total expenditures on green crab control programs.
This comparison raises the question whether the current expenditures on green crab management and control programs are enough. Unfortunately, it is impossible to answer this question without better understanding of the effectiveness of the control programs, the ecological effects of green crab invasion, and the value of the resources affected by green crabs.
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