Primary production required

AWAITING REVIEW

Indicator summary

Summary of indicator structure and function

Definition and/or background

The following is from Fulton et al 2004a -

Estimates of the primary production required (PPR) to support fisheries have already been used to ascertain pressure on the world’s aquatic systems (Ryther 1969, Vitousek et al. 1986, Pauly and Christensen 1995, Christensen 1995, Beddington 1995). PPR is a system level index of the impact of fishing, as it provides a measure of the influence of human activities (in this case fishing) on the lowest trophic levels of the ecosystem (Hall 1999). 

The index can be calculated in many ways, but is most easily calculated as a model-derived index from models such as ECOSIM, which uses:

where PPR_Ci is the PPR for the catch (C) of component i and is given by:

where P is production, Q is consumption, EE is ecotrophic efficiency (proportion of production that is directed to predation and catch) and DC is the diet composition for each predator-prey set in each path (Christensen et al. 2000).

Attribute

Ecosystem structure and function, community structure, trophic structure

Purpose

Fisheries

Data required

The following is from Fulton et al 2004a -

• Biomass per species (or group) recorded (preferably at least for the main components of the ecosystem and through time or vs. some reference area)
• Taxonomic data (or at least categorisation of the main components of the system)
• Catch data of species in fishery
• Mortality estimates for each group
• Consumption / Biomass estimates for each group
• Diet data

Ecosystem applicability

The following is from Fulton et al 2004a -

Should be applicable in all ecosystems.

Robustness

The following is from Fulton et al 2004a -

High: Work to date (Ryther 1969, Vitousek et al. 1986, Pauly and Christensen 1995, Christensen 1995, Beddington 1995) indicates that PPR is a good indicator of the system level effects of fishing. However, more widespread use of the indicator would provide insight into the true usefulness of the indicator in specific systems rather than at large regional scales. It would also show how robust the indicator is to the assumptions of the models it is derived from and to the quality of the data used to parameterise and initialise those models.

Current status and trends

The most thorough example to date of the use of PPR to consider the potential effects of fishing is Pauly and Christensen (1995). Pauly and Christensen (1995) not only calculate PPR for the world fisheries as a whole, but also consider habitat or region specific values. They estimated that 8% of global primary production is required to support the world’s fisheries. While this may seem like an insignificant amount it is on a par with global mean new production and therefore fisheries have a potentially enormous impact on the global ocean carbon cycle. When the regional estimates of Pauly and Christensen (1995) are considered, the potential for fisheries to impact upon diversity and system structure is clear. In upwelling and shelf systems Pauly and Christensen (1995) estimated that between 25 – 35% of the primary production is required to sustain the fish catches from these areas. This is close to the estimated levels of terrestrial primary production used to support humans (Vitousek et al. 1986) and the changes made to the terrestrial ecosystems to achieve this are obvious.

References

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.

References that Fulton et al uses for this indicator:

Beddington, J. R. 1995. The primary requirements. Nature 374, no. 16 March: pp 213-14.

Christensen, V. 1995. A model of trophic interactions in the North Sea in 1981, the Year of the Stomach. Dana 11, no. 1: pp 1-28.

Christensen, V., C.J. Walters, and D. Pauly. 2000. ECTOPATH with ECOSIM: a user’s guide. October 2000 edition. Fisheries Centre, University of British Columbia, Vanouver, Canada and International Centre for Living Aquatic Resources Management, Penang, Malaysia.

Hall, S.J. 1999. The effects of fishing on marine ecosystems and communities. Blackwell Science Ltd, Oxford.

Pauly, D., and V. Christensen. 1995. Primary production required to sustain global fisheries. Nature 374, no. 16 March: pp 255-57.

Ryther, J. H. 1969. Photosynthesis and fish production in the sea. Science 166, no. 3 Oct.: pp 72-76.

Vitousek, P. M., P. R. Ehrlich, A. H. Ehrlich, and P. A. Matson. 1986. Human appropriation of the products of photosynthesis. BioScience 36, no. 6: pp 368-73.

Background reading

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.

Citation

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