Overoptimism and the undervaluation of ecosystem services: A case-study of recreational fishing in Townsville, adjacent to the Great Barrier Reef

There are numerous methods for estimating the value of different types of ecosystem services. Some methods use observed behaviours to draw inferences about value, but (observed) behaviours are based upon expectations, which can be incorrect. Using data from anglers living in Townsville, adjacent to the Great Barrier Reef (GBR) in a travel-cost model, we show how expectations about the number of fish people believe they will catch on a recreational fishing trip greatly influence estimates of the value of catch reductions (a loss in angler welfare). Experienced fishers have much more accurate expectations about catch than infrequent fishers, highlighting that valuation estimates derived from observable behaviours are most robust when the service being valued is well-known and when people are able to accurately judge the outcome of their behaviours. More broadly, it is clear that under conditions of uncertainty – such as climate change – overly optimistic visions of the future will likely lead us to undervalue (and thus potentially degrade) key ecosystem services – perhaps substantially.