The simplest measure of population status is an estimate of the abundance at any given time. It is much easier to obtain relative than absolute abundance estimates, and a series of such estimates through time (an index) can be used to evaluate the population’s trend (i.e., increasing, declining, stable). The most commonly used index in fisheries management is based on standardized Catch per Unit Effort (CPUE).
Demographic analyses are used to provide quantitative population metrics that are used to quantify extinction risk and identify vulnerable life stages .
Productivity Susceptibility Analysis (PSA) is a semi-quantitative approach useful as an exploratory or triage tool that can be used to prioritize research, group species with similar vulnerability or risk, and provide qualitative management advice . Productivity can be described as the capacity of the stock to recover when depleted and susceptibility is the potential for the stock to be negatively impacted by the fishery [1, 2], however, definitions vary according to the parameters of the study. From estimates of these two components, the vulnerability of the stock can be computed.
The ‘risk analysis – open category’ catches those references that don’t easily fit other categories. For example, Astles (2015) argues that specific management and research actions relevant to smaller spatial scales can be developed by using the linkage between risk factors and risk treatment in ERA.
Stock assessments are a form of risk assessment, though they are not often referred to as such. They provide quantitative estimates of population status and the associated risk of exceeding biological reference points, such as maximum sustainable yield .