The economic value of freshwater inputs to an estuarine fishery

The health of many estuarine and coastal ecosystems depends on upstream hydrology; however, there is limited information on the economic effects of restricting freshwater flow to the coast. We investigate the role of freshwater inputs on the blue crab fishery in Georgia, USA. Blue crabs are known to respond to salinity changes in the estuaries in which they reside, and declining freshwater flow to the coast over the last 50 years is correlated with increases in average estuarine salinity and falling commercial harvests. A structural, bioeconomic model reveals freshwater inputs have significant effects on fishery outcomes. Simulations of a counterfactual minimum-flow standard for three different rivers, set at 25% of 50-year averages, suggest such a policy would result in measurable benefits for the fishery, improving profits by 35% ($1.7 million) during the period 2002–2012 in the three fishing areas for which data were available. Aggregating the necessary additional water releases to achieve this standard yields an approximate average value of water of between $1 and $7 per acre-foot.