Economics & Social Sciences Research Program
Estimating Regional Economic Impacts of Changes in an Alaska Crab Stock Yields
from Ocean Acidification
Fossil fuel emissions and deforestation have increased atmospheric CO2 concentrations, which have led to corresponding increases in oceanic CO2 concentrations, and hence, changes in carbonate chemistry of the oceans and decreases in ocean pH. Due to the increase in oceanic CO2 concentrations, the surface ocean pH has decreased on average by 0.1 units compared to pre-industrial levels. This is equivalent to a 30% increase in acidity of the surface waters. As CO2 levels continue to rise over the coming decades, the pH in the ocean will fall even further. A standard emissions scenario predicts that average pH in surface waters will fall from the current level of 8.1 to 7.8 before 2100.
This trend could have substantial physiological effects on marine organisms, affecting growth, survival, reproduction, and behavior. Calcifying organisms may be particularly affected because the reduction in pH makes it more difficult to excrete and sustain a calcified shell or exoskeleton. This will slow the growth of many marine fish species including crabs. As a result, the harvests of, and revenue from, harvests of fish species will decrease. The decrease in the revenue implies a reduction in the number of jobs in fish harvesting and processing sectors, and a decrease in the income of the stakeholders engaged in the fisheries. This will generate a wide range of economic impacts on the fishing-dependent communities.
A bioeconomic study by Dalton and Punt (2013) estimated the nonlinear effects of ocean acidification on survival parameters in stage structured pre-recruitment dynamics model; coupled the pre-recruitment dynamics model with a post-recruitment population dynamics model; and derived a sequence of Bristol Bay red king crab (RKC) yield curves for an ocean acidification scenario from 2009 to 2100, using the coupled model. Using the sequence of RKC yield curves, we calculated the temporal and cumulative regional economic impacts of the reduction in RKC yields on the Alaska economy using a recursive dynamic computable general equilibrium model. We also conducted some sensitivity analysis for an important parameter in the bioeconomic model to gauge robustness of our results.
By Chang Seung, Michael Dalton, André Punt