Data included
In the process of selection of species for discussion in this section, only EU- and candidate country-reported direct imports from wild, ranched and ‘unknown’ sources, as well as trade reported without a source specified, were considered. Terms that cannot easily be related to numbers of individuals (e.g. feathers, hair, specimens) were not included within the selection process, with the exception of certain terms[1] that were considered to be traded in sufficiently high quantities to merit further scrutiny.
In addition to the conversion factors applied to all trade data, the following conversion factors were applied to the data used in the selection process so that certain terms could be more easily equated to numbers of individuals.
Conversion factors applied to data used to select highly traded species.
| [l]Converted from: | [l]Converted to: |
|---|---|
| [l]Elephant tusks | [l]No. individuals [1.88 tusks = one elephant (Parker and Martin, 1982 )*] |
| [l]Hippopotamus teeth | [l]No. individuals [12 teeth = one hippopotamus] |
*Parker, I.S.C. and Martin, E.B. (1982). How many elephants are killed for the ivory trade? Oryx 16 (3): 235-239.
[1] Bark, caviar, extract, meat, musk, powder, raw corals, roots, timber and wax.
Selection criteria
The criteria for selection of species showing noteworthy patterns of trade are described below. Species were selected for discussion if they met at least one of the criteria.
High volume
Species qualified for selection on the basis of ‘high volume’ trade if imports during 2012 exceeded pre-determined thresholds based on taxa-wide assumptions of general reproductive biology.
High volume (Globally threatened)
The ‘high volume’ trade thresholds were adjusted for all species categorised as Critically Endangered (‘CR’), Endangered (‘EN’), Vulnerable (‘VU’) or Near Threatened (‘NT’) in the 2014 IUCN Red List of threatened species.
Sharp increase
Species qualified for selection on the basis of a sharp increase in trade if the volume of importer-reported imports during 2012 was more than three times the average trade volume of the preceding five-year period (2007-2011). Species that, despite a sharp increase in trade, were still only traded in very low volumes in 2012 (i.e. less than 5% of the high volume thresholds not taking into account threat status), were not selected on the basis of this criterion. Newly-listed species, or newly formed species following a nomenclature change, that met this criterion artificially due to the absence of trade records in previous years were also excluded.
Overall increase or decrease
General trends in trade for each species over the ten-year period 2003-2012 were identified by calculating the slope of a best-fit linear function to the trade data. For the purpose of comparison between species, the value of the slope was divided by the mean level of trade for each species over the ten-year period. Values greater than +0.15 and lower than –0.15 were considered large slopes. The goodness of fit of the trend-line was also taken into consideration; only species with R2 values greater than 0.75 were retained in the final selection. Species that, despite an overall increase in trade, were only traded in very low volumes in 2012 (i.e. less than 5% of the high volume thresholds not taking into account threat status), were not selected on the basis of this criterion. Species selected on the basis of an overall decrease in trade for which trade levels in the peak year of trade (i.e. prior to the decrease) were comparatively low (less than 5% of the high volume thresholds not taking into account threat status), or for which there was no trade in 2012, were excluded. Species that met the criteria artificially due to a taxonomic change were also excluded.
High variability
Variability was quantified using the coefficient of variation (the standard deviation divided by the mean) of the data over the ten-year period 2003-2012. Taxa were selected on the basis of this criterion if levels of trade showed a coefficient of variation greater than +2. Only species with non-zero data points in more than five years 2003-2012 were considered for selection. In the case of species added to the CITES Appendices within the period of analysis, only the years since its listing were analysed where a minimum of five years of data were available. Species that were traded in very low volumes in 2012 (i.e. less than 5% of the high volume thresholds not taking into account threat status) were also excluded.