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EAF Steps

Activity 2.2 - Issue Prioritisation and risk assessment

Purpose

The Productivity-Susceptibility Analysis (PSA) is a semi-quantitative and rapid risk assessment tool that relies on the use of life history characteristics of a stock (i.e., productivity) and its level of susceptibility to the fishery to determine a relative inherent vulnerability.

Overview

PSA is a method of assessing a fishery species or stock based on a comprehensive screening of risk for a set of predetermined measurable attributes. It is based on the assumption that the risk to a species depends on two characteristics: i) productivity of a species, which will determine the rate at which the unit can sustain fishing pressure or recover from depletion or other impacts due to the fishery; and ii) the susceptibility of the unit to fishing activities. The PSA analysis essentially measures the relative risk or the vulnerability of the resource to the potential fishery impacts. This approach is especially useful as it allows for a baseline comparison between many species with varying levels of available information. In the stocks discussed below, there are cases where full assessments have been regularly conducted, while for other stocks little is known other than distribution or life history characteristics.

The initially developed PSA approach examines attributes of each unit (stock or assemblage) with respect to productivity or susceptibility to provide a relative measure of risk to the unit. Productivity is measured by averaging the seven attributes. Susceptibility is estimated as the product of four independent aspects; availability, encounter-ability, selectivity and post-capture mortality (PCM); these aspect values are composed of attributes. The productivity and susceptibility of a stock is determined by providing a score ranging from 1 (low) to 3 (high) for the each of the attributes. The scores for the productivity and susceptibility indices are calculated and can be graphically displayed on an x-y scatter plot.

A modified version of PSA has been developed and adopted by NOAA. This includes an additional four management components for measuring susceptibly including management strategy, fishing mortality and biomass of spawners, plus survival of released fish.

EAF Tool Tips

The initial version of the PSA does not produce a stock status assessment, but an evaluation of resource vulnerability, which is often useful to determine which species are likely to be at higher risk in a fishery or an ecosystem.

For the NOAA modified version of PSA, as the exploitation rate and the biomass level of a stock are used or at least estimated then this essentially converts this into a quantitative stock assessment analysis.

EAF Tool Pedigree

The PSA was originally developed to classify differences in bycatch sustainability in the Australian prawn fishery (Stobutzki et al. 2001) by evaluating the productivity of a stock and its susceptibility to the fishery. The PSA was later modified in 2004 by the Commonwealth Ecological Risk Assessment ERA team (Hobday et al. 2007). A modified version of this method is now used by NOAA (Patrick et al., 2010).

EAF Tool Synergy

This can be a useful precursor to any of the full risk assessment or stock assessment techniques because it documents many of the traits that are needed to complete both of these types of assessments.

EAF Tool Usage

Fairly hard

Cost

Moderate

The costs will generally be associated with the collation of data and expertise to use this method appropriately.

EAF Tool Capacity

Moderate

This is a technical process that requires sufficient expertise and experience to as accurately as possible assign determine what criteria scores are most appropriate for across a large spectrum of areas for a species. .

Background Requirements

Moderate – High

The initial version of the PSA requires either direct information on a number of attributes of the species being examined or at least reasonable proxies based on data from similar types of species collected elsewhere. The NOAA version of the PSA version more like a full stock assessment hence the data requirements are clearly much greater than for the initial version.

Participation

Low

This is a technical exercise not one for large levels of stakeholder participation.

Time Range

Short – Moderate

The majority of the time to complete this process is to gather the data necessary to complete the analysis. If the data are available in an accessible form then the process can be completed in a few days.

Source of Information

Hobday, et al. (2007) Ecological risk assessment for the effects of fishing: methodology.  Internet resource
Use of Productivity and Susceptibility Indices to Determine Stock Vulnerability, with Example Applications to Six U.S. Fisheries.  Internet resource
First Workshop on the Assessment of fishery stock status in south and southeast Asia Internet resource

Other Relevant References

Stobutzki et al . 2001. Sustainability of fishery bycatch: a process for assessing highly diverse and numerous bycatch. Environmental Conservation 28:167-181. Internet resource
 
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