meanMaxLength: Calculates the Mean Maximum Length of fish in the community
In marindicators: Marine Ecosystem and Fishing Pressure Indicators

Description Usage Arguments Details Value Author(s) References See Also Examples

This function calculates the Mean Maximum Length of fish in the community weighted by biomass or abundance for j areas and i years.

1 2	meanMaxLength(X, group, species.table = NULL, maxlength.table, metric, years)

`X`	A dataframe of fishery independent data derived from research vessel survey data or model output, with columns `YEAR`, `ID`, `SPECIES`, and `BIOMASS`. `YEAR` indicates the year the observation was recorded, `ID` is an area code indicating where the observation was recorded, `SPECIES` is a numeric code indicating the species sampled, and `BIOMASS` is the corresponding biomass (stratified and corrected for catchability as required).
`group`	character string indicating which species to include in the indicator calculation. If `group = "ALL"`, all species will be included; otherwise, `group` should match a column name in `species.table`.
`species.table`	A table where the column names match the entries in `groups`. Column entries are species codes indicating the species from `X` included in each group. `species.table` may also include columns for other species groups; these will be ignored. If `groups = "ALL"`, this table is not required. Default is `species.table = NULL`.
`maxlength.table`	A dataframe with columns `SPECIES` and `MAXLENGTH`, the maximum recorded length of the corresponding species. Entries in the `SPECIES` column should be the unique values of species codes in `X` (or a subset thereof). Other columns in `maxlength.table` are ignored.
`metric`	A character string indicating which column in `X` to use to calculate indicator. Default is `metric = "BIOMASS"`.
`years`	A vector of years for which to calculate indicator.

Mean Maximum Length:

Mean Maximum Length = Σ (L_{max,i}*M_i)/Σ M_i

where L_{max,i} is the maximum asymptotic length (cm) of species i, and M_i is biomass or abundance of species i (excluding invertebrates; Shin et al., 2005).

Returns a dataframe with 3 columns. ID, YEAR, and MMLength_metric.

If there is no data for spatial scale j in year i, indicator value is assigned NA.

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.

Shin YJ, Rochet MJ, Jennings S, Field JG, Gislason H. 2005. Using size-based indicators to evaluate the ecosystem effects of fishing. In: ICES Journal of Marine Science. p 384-396

Other stability and resistance indicators: CVBiomass, IVILandings, allStability, biomassPerTL, meanMaxAge

# Compile data
data(X)
data(species.info)
data(species.table)

# Calculate indicators
# Weighted by abundance
meanMaxLength(X, group = "FINFISH", species.table = species.table, 
   maxlength.table = species.info, metric = "ABUNDANCE", years = c(2014:2019))
#Weighted by biomass
meanMaxLength(X, group = "FINFISH", species.table = species.table, 
   maxlength.table = species.info, metric = "BIOMASS", years = c(2014:2019))