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This page provides some background and justification for the headings selected to describe each indicator.

Definition and/or background

"Ecosystem indicators are generally accepted as tools for evaluating ecosystem status and trends (e.g. Shin & Shannon 2010, Shin et al. 2010a,b), identifying key ecosystem processes (e.g. Ojaveer & Eero 2011), serving as signals that something is happening beyond what is actually measured (NRC 2000), and assessing the impacts of human activities and climate forcing (e.g. Coll et al. 2010, Link et al. 2010b, Ojaveer & Eero 2011)." (Fu et al 2012). Indicators can be a useful tool within management frameworks for purposes of communication and decision making (Vandermeulen 1998). Indicators can provide information on trends in the conditions of a phenomenon and has significance extending beyond that associated with the properties of the statistics itself (Vandermeulen 1998). Simple indicators have been found out perform more complex (model based) ones, which are sensitive to data quality (Fulton et al 2005, Link 2005). Indicator performance can be quantified by the ability to detect and/or predict trends in key variables of interest (attributes) (Fulton et al 2005). There is consensus on the need for multiple rather than a single indicator and on the types of indicators that perform well regardless of system type (Medley et al 2009).

 Fulton et al., (2005) and Link (2005) have shown that it is critical that:

  • a suite of indicators, which are not all highly correlated, is used;
  • multiple time and space scales are spanned by the data sets

It is also critical that data include species that (Medley et al 2009):

  • are directly impacted;
  • have high turnover rates, which may provide a noisy but early warning;
  • define the habitat, as these often have a disproportionate or keystone role in the system; and
  • are from the upper trophic level, which are typically both vulnerable in their own right due to their life history characteristics, but also integrative of pressures and patterns at large scales.


For each indicator a definition of what that indicator is and any background information about that indicator should be included in this section.


The following is from Fulton et al 2004a -

We use the term attribute to refer to a quantity or aspect of a system that is the real focus of interest or concern. Attributes often correspond to the subject matter in high-level management objectives, such as “(improve) ecosystem health”, “(maintain) ecosystem integrity” and “(conserve) biodiversity” (Fulton et al. 2001). Unfortunately, attributes may not be directly measurable quantities. As a result, indicators that characterise the state of the attribute of interest and then track, or predict, significant changes in this state are used. Where attributes are directly measurable, the attribute and indicator will be identical, such as population biomass, for species where this can be measured. Where direct measurement is impossible or impractical, a suitable indicator is chosen that is a proxy for the attribute of interest. Where the attribute is biomass, a common proxy in fisheries assessment is the catch rate for the species in question. There can be many indicators for the same attribute. The key is to find “robust” indicators that are good proxies for the corresponding attributes, and cost effective in terms of measurement...

In this section list any attributes that are related to this indicator.

Examples of ecological attributes (from  Fulton et al (2004a)) include:

  • ecosystem structure -
  • ecosystem function
  • community structure
  • community function
  • Eutrophication
  • trophic shifts
  • trophic structure
  • habitat quality
  • discard availability
  • population structure
  • predator-prey balance
  • community heterogeneity
  • habitat condition
  • efficiency of by-catch reduction measures 


What area is this indicator aiming to inform? What is the purpose of the indicator?

The idea of this section was to inform whether the indicator has been developed for fisheries or something else. Initially most of the indicator literature found only dealt with fisheries, therefore wanted to provide a quick reference highlighting which indicators were used for fisheries management and which were for some other management use.


List any taxa that this indicator may be restricted to or if there are any taxa that are particularly suited to this indicator.

This taxa section should include links to any biota profiles that are relevant to the indicator.

Data required

List any data that is required to calculate this indicator.

Ecosystem applicability

Indicators can be limited to a certain ecological area depending on the type of data that is required or they can be used across all ecosystem. Many indicators are still being development and their use across all ecosystems is currently in review based on data available and the types of ecosystems that the indicator was initially developed for. This section is intended to highlight any ecosystems that an indicator is not suited to, has not been tested for, or if it is suitable to be used in all ecosystems.

Identified capability

Appropriate definitions required

demonstrable =  this indicator definitely shows this by these studies, data sets, etc.

aspirational =  this indicator may show this we think but have no data or studies to back it up..which just think that it is a link that can be made.

Biological classification level

For each indicator the biological classification level is given, it can be more that one if appropriate.

The indicators listed in this wiki are classified into levels of organisation (based on those described by Fulton et al (2004)). The biological classification levels are species, population, assemblage, community, and ecosystem. Fulton et al (2004) do not include a species level but does include an individual level which they describe as being highly restricted and of uncertain benefit. This individual level has been renames species in this wiki.

The species level focuses on behavioural and metabolic responses (Fulton et al 2004).

The population level focuses on behaviour, demographic, metabolic and genetic responses and includes biomass, production and size structure (Fulton et al 2004). These examples are often used an proxies of population health and can also potentially be used for community and ecosystem proxies. Population level indicators are the most operational indicators because they (Fulton et al 2004):

  • are more easily interpreted
  • have a greater level of understanding of their properties and how they effect fishing (reference points are more easily set for these types of indicators)
  • show that if individual species in the ecosystem are conserved then it is difficult to say that the ecosystem is not being preserved. 

Currently there is a better understanding and familiarity with population indicators and sound theoretical bases which makes then attractive candidates as surrogates for more general effects of fishing on ecosystems. Although more scientific understanding is needed to evaluate their true worth as long term indicators of ecosystems. Population indicators are good indicators of the state of a particular species but are less certain when used as proxies for community and ecosystem attributes (Fulton et al 2004).

  • (e.g. mortality rate, exploitation rate, or average length) are the most operationally useful indicators because their meaning is clear and the expected effect of fisheries on them is well understood, , ie. reference points can be set (Rochet and Trenkel 2003).
  • first step from single-species to community assessment and management. These indicators have the goal of preserving population states, structures and dynamics (Rochet and Trenkel 2003).

The community level concentrates on species richness, diversity and habitat structure and is primarily concerned with community and trophic structure and the processes or environmental conditions that support these structures (Fulton et al 2004). Community indicators according to Rochet and Trenkel (2003) are networks of interacting populations or individuals. The goals of these indicators are to assess the effect of fishing on the interactions, the tropic paths, and the biomass flows in the community and for the preserving of the above functions of the community (Rochet and Trenkel 2003).

There are some problems with community indicators (Fulton et al 2004) including that:

  • they do not only respond to changes in fishing but also to changes in natural regime shifts and eutrophication
  • fisheries dependent data can be bias by shifts in market forcing and technology advances
  • reference points are not easily identified because need unexploited regions to determine the reference points, of which there are few.

The ecosystem level includes entire ecosystem processes such as production or overall tropic structure and include indicators such as productivity, nutrient cycling and diversity. There have been very few ecosystem studies completed and therefore most ecosystem indicators have been developed from ecological theory or from ecosystem models (Fulton et al 2004). The types of ecosystem indicators include:

  • estimates of changes in the community biomass as a result of fishing down the food web (FIB)
  • measures of productivity
  • departure of Redfield ratio
  • ratio of biomass of demersal and pelagic species.

There are some problems with ecosystem indicators including, that they are not good early warning indicators, are less sensitive to change and the best indicators are entirely based on models. These models are still in development and need more rigorous scrutiny therefore indicators may not be as robust as lower level indicators (Fulton et al 2004). There are also some good aspects to ecosystem indicators; they are good at describing ecosystem health and are more suited to performance reporting than to decision making (Fulton et al 2004).

Response variables

The indicators can also be divided based on their response variable. We have selected four possible variables to be used in this wiki.

Size-based indicators (SBIs) -

  • Is the statistical summary of the size distribution of fish assemblages and populations. The size of an organism is a central factor to key ecological processes. The changes in size distribution may have many ecological or physical causes, including genetic or environment variability in life history characteristics, predictor-prey relationship, and competitive interactions (Shin et al 2005).
  • Fishing is always size selective (ie, nets used, target species and by-catch).
  • 'Are typically used to describe the response of communities or individuals populations to exploitation and may contribute to the development of an ecosystem approach to fisheries' (Shin et al 2005).
  • Can be used for other species beside fish.

Species-based indicators -

  • Species-based indicators are frequently used as surrogates for measures of environmental condition and wider biodiversity health. Species selection is crucial in determining an indicator’s metric value and therefore the validity of the interpretation it provides (Butler et al 2012).
  • Are often broken down into large groups (eg, mammals, fish, birds, etc).
  • These indicators can be used to inform the IUCN Red List, which provides evaluations of the conservation status of species by comparing information on distribution, population and trends over time, with standardised quantitative criteria for each of the categories of threat (Critically Endangered, Endangered and Vulnerable) (see the IUCN Biodiversity document for more details).

Trophodynamic indicators -

  • Trophodynamic interactions centre around predation and competition.
  • Are most relevant to the mean trophic level of community and the demersal-to-pelagic biomass ratio (Fu et al 2012).

Environmental indicators -

  • Are are most likely related to total system biomass and biomass of specific biological groups variables, (Fu et al 2012).


The drivers as described in various studies (eg Fu et al 2012; Pranovi et al 2012 and Link et al 2010) are anthropogenic, trophodynamic and environmental. These three drivers are the main processes that regulate the production dynamics of a marine ecosystem (Link et al 2010). There are plenty of studies that have shown how each of these drivers acts singly on a system and only recently have studies begun to look at multiple drivers assessed simultaneously (Link et al 2010). The driver can be divided into two types; anthropogenic and environmental drivers are external to the ecosystem and whereas trophodynamic drivers are not. As a result of this relationship anthropogenic and environmental driver can strongly influence trophodynamic drivers in an marine ecosystem (Pranovi et al 2012).

The anthropogenic drivers (also called fisheries)

  • Encompasses fisheries exploitation.
  • They tend to be related to catch-based indicators (Fu et al 2012).
  • Fisheries drivers can be derived from the catch time series for an ecosystem (Fu et al 2012).
  • These can be analysed on a species basis, in feeding guilds, or by combining feeding guilds (Fu et al 2012).

The trophodynamic drivers (also called trophodynamic interactions)

  • Tend to be related to the mean tropic level of the community (Fu et al 2012). 
  • Include time series related to predator-prey of fishes species (Fu et al 2012).
  • Used to examine bottom up and top down effects on fisheries production (Fu et al 2012).

The environmental drivers (also called biophysical)

  • Looks at local and basin scale climate factors.
  • Temperature one of the strongest environmental drivers. (Fu et al 2012).
  • Represent thermal or broad-scale oceanographic features that are influential in an ecosystem. (Fu et al 2012).
  • Examples include: SST, various ocean oscillation and indexes, stratification, freshwater discharge, sea ice cover.


The robustness level of each indicator is based on the definition outlined in Fulton et al (2004) Final Report.

The following if from Fulton et al 2004a -

Many of the descriptions of the different types of indicators given below refer to a robustness rating. This is a subjective rating (low, medium, high), given to each indicator reviewed by Fulton et al. (2004a), that was based on a literature review (and where necessary an expert judgement) on the conceptual foundation, feasibility of implementation, ease of accurate collection, sensitivity, exclusiveness, comprehensiveness and clarity of potential indicators (Jackson et al. 2000, ICES 2001, Rochet and Trenkel 2003, Fulton et al. 2004a, Niemi et al. 2004, Rice and Rochet 2004, Rochet and Rice 2004). While some preliminary indicator assessment frameworks were trialed during the early stages of this project, in collaboration with members of the SCOR working group 9 (WG9) on the quantitative indicators of the ecological effects of fishing, the ratings ultimately subjective, as no tested quantitative selection criteria existed when the review took place. The final form of the SCOR WG9 indicator evaluation framework does appear to show substantial promise, but they have come too late for inclusion in this study.

 In general, a poor rating based on this subjective system did mean an indicator was dropped from further consideration by simulation testing. However, if an indicator has been strongly advocated in the past, is already widely used, or if field work had indicated that it may actually have potential, then it was included (if possible given the form of the model) regardless of rating.

Examples of an indicator in use

These next three section are management oriented and are here to provide examples of how an indicator is used in a system.

Current status and trends

Information that could be described in this section includes:

  • What was it like in an undisturbed/unexploited system?
  • How would it be expected to change?
  • Which direction is the indicator showing a system is going in - steady, decreasing or increasing?

The trend associated with meeting an operational objective can be a limited or target reference point, trajectory or direction. Target stock use in management plans has a tradition of setting reference points (Jennings 2005). In other fields a reference point can not be made therefore a trajectory or reference direction is used instead. See figure below from Jennings 2005 for an example of points, trajectories and directions. The unexploited, target, precautionary and limit are reference points where as the green arrows are the trajectories or reference directions. These are all measurement of progress of the management performance.

Reference points that might support management decision making (Jennings 2005) include:

  • reference points that show an undisturbed or unexploited system.
  • limit reference points that show the values of indicators associated with serious or irreversible harm.
  • target reference points that show the preferred values of the indicators.
  • Precautionary reference points may be used to guarantee a high (preferably specified) probability of avoiding a limit because most indicator values include error.

Management strategies and/or objectives

Information that could be described in this section includes:

  • Has it been used in a management strategy? if so how?
  • What is the relationship to management strategies/ objectives?
  • Which of the four specific management objective (adapted from Indiseas) has been used for this indicator?
    • Conservations biodiversity - 
    • Ecosystem stability and resistance to perturbations -
    • Ecosystem structure and functioning -
    • Resource potential -

Need to add definitions to the above objectives

Stakeholder/public acceptability

Information that could be described in this section includes:

  • Is the indicator understandable to the public? stakeholders?
  • Does the public and/or stakeholders need further education about an indicator and how it is used for management objectives?
  • What is the acceptability with stakeholders? Answers include:
    • It is widely accepted
    • There is good public awareness
    • There is weak public awareness
    • There is no public awareness
    • It is unknown

Is more background info is needed for this section?

Useful weblink and initiatives for an indicator.


Bulter, SJ., Freckleton, R.P., Renwick, A.R. and Norris, K. (2012) An objective, niche-based approach to indicator species selection, Methods in Ecology and Evolution, 3(2), 317-326.

Fu, C., Gaichas, S., Link, J.S., Bundy, A., Boldt, J.L., Cook, A.M., Gamble, R., Utne, K.R., Liu, H., and Friedland, K.D. (2012) Relative importance of fisheries, trophodynamic and environmental drivers in a series of marine ecosystems. Marine Ecology Progress Series, 459, 169-184.

Fulton, E.A., Fuller,M., Smith, A.D.M., and Punt, A. (2004) Ecological indicators of the ecosystem effects of fishing: Final report. AFMA Final Research Report, report Number R99/1546.

Fulton, E.A., Smith, A.D.M., Webb, H., and Slater, J. (2004a) Ecological indicators for the impacts of fishing on non-target species, communities and ecosystems: Review of potential indicators. AFMA Final Research Report, report Number R99/1546.

Fulton, E.A., Smith, A.D.M. and Punt, A.E (2005) Which ecological indicators can robustly detect effects of fishing? ICES Journal of Marine Science. 62, 540-551.

Jennings, S. (2005) Indicators to support an ecosystem approach to fisheries. Fish and Fisheries, 6, 212-232.

Link, J.S.,Megrey, B.A., Miller, T.J., Essington, T., Boldt, J., Bundy, A., Moksness, E., Drinkwater, K.F. and Perry, R.I. (2010) Comparative analyssi of marine ecosystems: international production modelling workshop. Biology Letters 6, 723-726.

Medley, P.; Cheung, W.; Fulton, B.; Minte-Vera, C. (2009) Multispecies and ecosystem indicators, and biomass-fleet dynamics stock assessment: an initial evaluation. FAO Fisheries and Aquaculture Circular. No. 1045. Rome, FAO. 28p

Pranovi, F., Link, J., Fu, C., Cook, A.M., Lui, H., Gaichas, S., Freidland, K.D., Utne, K.R., and Benoît, H.P. (2012) Trophic-level determinants of biomass accumulation in marine ecosystems. Marine Ecology Progress Series, 459, 185-201.

Rochet, M-J. and Rice, J.C. (2005) Do explicit criteria help in selecting indicators for ecosystem-based fisheries management? ICES Journal of Marine Science. 62, 528-539.

Rochet, M-J. and Trenkel, V.M. (2003) Which community indicators can measure the impact of fishing? A review and proposals. Canadian Journal of Fisheries and Aquatic Sciences, 60 (1) 86-99.

Background reading

Other references that would be useful to read in regard to the indicator referred to on this page.



Please cite this page as:
SOKI Wiki (2014) Friday 11 Apr 2014.

Page created by:Shavawn Donoghue

Last modified on: Apr 11, 2014 14:53

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