These pages are still under construction |
| Indicator | Attribute | Purpose | If restricted to taxa, list which ones | Ecosystem applicability | Identified capability | Biological classification level | Response variable | Drivers | Robustness |
|---|---|---|---|---|---|---|---|---|---|
| Mean trophic level | Trophic shifts, trophic structure | fisheries | Applicable to all systems | Aspirational | Ecosystem | Trophodynamic | Anthropogenic | Medium to high |
| Indicator examples | Current status and trends | Management objective/direction | Stakeholder/Public acceptability |
|---|---|---|---|
| Examples of how the indicator is used. | Pick one of the following:
| Pick one of the following:
| Pick one of the following:
|
The following is from Fulton et al 2004a -
Fish communities can be relatively hard to study (Jennings et al. 2001) and summary statistics for general community characteristics are very useful. One such statistic is mean trophic level, which can also be a good indicator of the effects of fishing (due to the preferential targeting of fish from higher trophic levels by fisheries). ... While this is an attractive indicator, the best means of calculating it has yet to be decided upon and it is likely to require a lot of data (e.g. diet information) and so may only be useful only in well-studied ecosystems (Rochet and Trenkel 2003).
Mean trophic level of the catch has also been used as a summary statistic for the consideration of broad-scale, coarsely resolved datasets such as the FAO dataset. The index is also the basis for other indicators, such as the “Fishery is balanced” (or FIB) index (see separate page). While these catch-based statistics can be informative, great care must be taken that they are not being confounded by economic forces guiding targeting or technological advances (Caddy and Garibaldi 2000).
Trophic shifts, trophic structure
fisheries
The following is from Fulton et al 2004a -
The following is from Fulton et al 2004a -
Applicable to all systems.
Is there any additional information that would be of interest in regards to the identified capability?
Otherwise can leave this section blank and just fill in the table instead.
Is there any additional information that would be of interest in regards to the biological classification?
Otherwise can leave this section blank and just fill in the table instead.
Is there any additional information that would be of interest in regards to the response variable?
Otherwise can leave this section blank and just fill in the table instead.
Is there any additional information that would be of interest in regards to ecological drivers?
If not can leave this section blank and just fill in the table instead.
The following is from Fulton et al 2004a -
Medium to High: if based on fisheries independent data the trends in this statistic give a good indication of changes in community structure that result from the effects of fishing. The robustness is weakened if based solely on catch data (as that can be confounded by the usual concerns about catch data such as targeting and reporting), but it is still relatively sound given the simplicity and ease with which the indicator can be calculated. The indicator can be effected by other changes in the environment that also effect community composition, such as eutrophication, but that is true of all indicators considering community structure.
The following is from Fulton et al 2004a -
A drop in the mean trophic level has been seen in both temperate (e.g. North sea, Greenstreet and Hall 1996) and tropical systems (e.g. Islands of the Philippines, Russ and Alcala 1996) and indicates a substantial shift in community structure as smaller, faster growing species which feed lower in the food web come to dominate the system.
define a standard set of management objectives?? ie from Indiseas
has it been used in a management strategy? if so how?
relationship to management strategies/ objectives
Acceptability with stakeholders
Hyperlinks to organisations, databases, webportals, and ID books, that are associated with this indicator, if appropriate.
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:
Caddy, J. F., and L. Garibaldi. 2000. Apparent changes in the trophic composition of world marine harvests: the perspective from the FAO capture database. Ocean & Coastal Management 43: pp 615-55.
Greenstreet, S. P. R., and S. J. Hall. 1996. Fishing and the ground-fish assemblage structure in the north-western North Sea: an analysis of long-term and spatial trends. Journal of Animal Ecology 65: pp 577-98.
Jennings, S., M.J. Kaiser, and J.D. Reynolds. 2001. Marine fisheries ecology.,. 417 p . London: Blackwell Science.
Rochet, M.-J., and V. M. Trenkel. 2003. Which community indicators can measure the impact of fishing? a review and proposals. Canadian Journal of Fisheries and Aquatic Science 60: pp 86-99.
Russ, G. R., and A. C. Alcala. 1996. Marine reserves: rates and patterns of recovery and decline of large predatory fish. Ecological Applications 6 , no. 3: pp 947-61.
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.
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