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A Macroecological Approach to Forecasting Fisheries Services: How much Energy Does it Take to Catch a Fish?
Citation:
MCGARVEY, D. J. AND J. M. JOHNSTON. A Macroecological Approach to Forecasting Fisheries Services: How much Energy Does it Take to Catch a Fish? Presented at CAU/GFO Workshop: Ecosystem Services - Solution for Problems or a Problem that Needs Solution, Kiel, GERMANY, May 13 - 15, 2008.
Impact/Purpose:
The U.S. Environmental Protection Agency is currently developing methods to quantify freshwater fisheries services (e.g., standing-stock abundance and/or biomass) at multiple spatial scales, and to forecast their future distributions.
Description:
The U.S. Environmental Protection Agency is currently developing methods to quantify freshwater fisheries services (e.g., standing-stock abundance and/or biomass) at multiple spatial scales, and to forecast their future distributions. One approach uses linked, ecosystem process models (e.g., hydrologic dynamics, nutrient cycling, and density-dependant growth) to simulate fisheries responses to a suite of anthropogenic disturbances, such as land use changes and global climate change. This integrated methodology can generate robust predictions with known accuracy and precision (through sensitivity and uncertainty analyses), but is difficult to implement across regions, given the large datasets needed for model parameterization and validation. An alternative, macroecological approach capitalizes on first principles of aquatic ecosystem metabolism by estimating the total energy (i.e., in situ primary production plus allocthonous inputs) within a given system, then partitioning that energy among resident fish populations. This strategy is robust because all fish species have similar metabolic requirements, when considered on a per-unit-mass basis. The macroecological approach also requires relatively little a priori knowledge of environmental conditions or species’ life-histories; documented relationships between primary productivity and stressors of concern (e.g., the relationship between stream temperature and primary productivity), and basic information on regional species distributions are sufficient. It is therefore more flexible than the mechanistic modeling approach, and more amenable to regional and national-scale predictions. However, it is also a less powerful tool for predicting fisheries services at local-scales, with a high degree of precision. To demonstrate the advantages and limitations of the macroecological method, we present a series of current and future predictions, regarding fisheries services in the Albemarle-Pamlico River System of eastern Virginia and North Carolina (USA).