Managing the Impacts of Human Activities on Fish Habitat: The Governance, Practices, and Science

Using Habitat Area-Production Relationships for Assessing the Productive Capacity of Fish Habitat

Robert G. Randall


Abstract.—Habitat Area-Production relationships (HAP) are advocated for determining first-order estimates of the productive capacity of different ecosystems and fish habitat types. HAP is a two-step method. First, an estimate of habitat capacity is determined by regressing surface area of lakes, rivers or marine areas against total production (or a proxy of production) for each area. Area-production plots are not novel, but the premise of this paper is that surface area is often the dominant factor that determines total fish production for a region or site. The second step is to investigate the region- or site-specific environmental drivers or habitat factors that affect production. Case studies based on literature data are used to demonstrate the utility of the HAP method of estimating habitat capacity in freshwater and marine areas, both among and within ecosystems, and at different spatial scales. Advantages of the area-production relationship approach are: 1) first-order estimates of productive capacity, explicitly showing the relative importance of the quantity and quality of habitat, can be determined if surface area-production data are available for specific regions; 2) area-production plots will guide further research for refining habitat function and capacity; 3) HAP provides a quantitative method of identifying both habitat perturbations and important habitat; 4) a lack of a significant area-production relationship may be instructive; and 5) the method can be applied at different spatial scales in different ecosystems. HAP relationships can be used to determine region-specific benchmarks of habitat productive capacity and to guide monitoring to assess the effectiveness of habitat restoration.