This function calculates the Intrinsic Vulnerability Index (IVI) of the commercial landings for j areas and i years.
A dataframe of commercial landings data with columns
A dataframe with columns
A vector of years for which to calculate indicator.
The weighted Intrinsic Vulnerability Index (IVI) of species in the commercial landings was estimated as:
IVI = Σ(IVI_j * C_j)/Σ C_j
where the sum is over all species, j. The vulnerability for each species was determined by considering several traits including maximum length, age at first maturity, longevity, von Bertalanffy growth parameter, natural mortality, fecundity, spatial behaviour and geographic range (e.g. species with larger body size, higher longevity, higher age at maturity, and lower growth rates have higher vulnerability indexes and should be less able to sustain high fishing mortality; Cheung et al. 2005). The index values ranges from 1 to 100, with 100 being the most vulnerable. See Appendix 1 from Cheung et al., 2007: http://www.int-res.com/articles/suppl/m333p001_app.pdf
Returns a dataframe with three columns:
If there are no observations in
land for spatial scale j in
year i, indicator value is assigned
Danielle Dempsey Danielle.Dempsey@dfo-mpo.gc.ca, Adam Cook, Catalina Gomez, Alida Bundy
Bundy A, Gomez C, Cook AM. 2017. Guidance framework for the selection and evaluation of ecological indicators. Can. Tech. Rep. Fish. Aquat. Sci. 3232: xii + 212 p.
Cheung WWL, Pitcher TJ, Pauly D. 2005. A fuzzy logic expert system to estimate intrinsic extinction vulnerability of marine fishes to fishing. Biol Conserv 124:97–111
Cheung WWL, Watson R, Morato T, Pitcher, TJ, Pauly, D. 2007. Intrinsic vulnerability in the global fish catch. Mar Ecol Prog Ser 333: 1 - 12
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