Assess Risk

The fourth step in the NOAA Integrated Ecosystem Assessment (IEA) approach is to conduct a risk assessment. Risk assessments determine the probability of undesirable events occurring to the ecosystem components identified in the first step of the IEA. Risk is generally described by the sensitivity and/ or resilience of a given ecosystem component (measured by the indicators) to various natural and human pressures and perturbations (including management actions) that result in a change in the system. Such analyses can be either highly quantitative (e.g. using complex ecosystem models) or can apply more qualitative approaches (e.g. using qualitative network modeling approaches).

Benefits of Assessing Risk

Risk assessments help prioritize management action and set the stage for analysis of trade-offs through management strategy evaluation.

Approaches and Tools to Conduct Ecosystem Risk Assessments

Ecosystem Risk Assessments (ERA) evaluate the cumulative impacts of multiple pressures on multiple ecosystem components. Whereas traditionally, marine risk assessments focused on singular pressure-response relationships. Given the multitude of interactions within coupled natural–human (CNH) systems, one of the primary benefits of Ecosystem Risk Assessments is characterizing impacts and the associated risks of these impacts to key components of both biological and human communities.

NOAA IEA natural and social scientists developed a framework to determine what kind of Ecosystem Risk Assessments should be conducted for coupled socio-ecological systems. The framework has two dimensions:

  • The level of analytical approach needed
  • The complexity of coupled natural-human systems of interest

Selection of the level of Ecosystem Risk Assessment to carry out should be based on the urgency, research capacity, and most importantly management need to evaluate cumulative and indirect impacts and/or multi-sector tradeoffs. This framework builds off of the Hobday et al (2011) approach for fisheries risk assessments that moves from qualitative analyses to semi-quantitative, to fully quantitative.

Ecosystem Risk assessment framework
This figure depicts the ecosystem risk assessment framework which helps determine what kind of Ecosystem Risk Assessments should be conducted based on level of system complexity and class of analytical complexity needed. Click on the blue buttons to learn more about each level and class. (Holsman et al. 2017)


  1. 1. Battista, Willow, et al. "Comprehensive Assessment of Risk to Ecosystems (CARE): A cumulative ecosystem risk assessment tool." Fisheries Research 185 (2017): 115-129.

  2. 2. Fletcher, W.J.; "Review and refinement of an existing qualitative risk assessment method for application within an ecosystem-based management framework", ICES Journal of Marine Science, Volume 72, Issue 3, 1 March 2015, Pages 1043–1056

  3. 3. Holsman, K., J. Samhouri, G. Cook, E. Hazen, E. Olsen, M. Dillard, S. Kasperski, S. Gaichas, C. R. Kelble, M. Fogarty, and K. Andrews. 2017. An ecosystem-based approach to marine risk assessment. Ecosystem Health and Sustainability 3(1):e01256. 10.1002/ehs2.1256

  4. 4. Hobday, A. J., et al. "Ecological risk assessment for the effects of fishing." Fisheries Research 108.2-3 (2011): 372-384.

  5. 5. Samhouri, Jameal F., et al. "An ecosystem-based risk assessment for California fisheries co-developed by scientists, managers, and stakeholders." Biological Conservation 231 (2019): 103-121.

  6. 6. Samhouri, Jameal F., and Phillip S. Levin. "Linking land-and sea-based activities to risk in coastal ecosystems." Biological Conservation 145.1 (2012): 118-129.
NOAA's INtegrated ecosystem assessment step 4 assess risk
NOAA's Integrated Ecosystem Assessment

Regional Risk Assessments:

Other relevant Ecosystem Risk Assessment frameworks include:

  • Hobday et al (2011) Ecological risk assessment for the effects of fishing
  • Samhouri and Levin (2012) Linking land- and sea-based activities to risk in coastal ecosystems
  • Fletcher, WJ (2014) Review and refinement of an existing qualitative risk assessment method for application within an ecosystem-based management framework
  • Batista et al (2017) Comprehensive assessment of risk to ecosystems (CARE): A cumulative ecosystem risk assessment tool

Related activities: