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Reference data summary

EMW ref. id
"Estimated mean weight" reference id. References are assigned an id m where m is an integer starting with 1 for each EMW id. This is a hyperlink to screen 4.
FAO species category
A species or group of species reported in FAO fisheries capture statistics.
The species for which the mean weight is estimated. This will be different from FAO species category in cases where the estimated mean weight applies to the smallest or largest species of a multi species category.
Scientific name
The Scientific name for Species.
Lower (or upper) estimated mean weight (EMW)
The lower (or upper) end of the estimated mean weight range weight that would be estimated for this Species if based on this reference alone.
Used for lower or upper EMW figure?
This indicates whether the fish size data applies to both the lower and upper end of the estimated mean weight range, or just one of them. "Both" means it does e.g. "the average weight is 1-2 Kg". "Upper" means the fish size data applies to the upper end only of the range e.g. "most fish taken in commercial catches are less than 1 Kg". "Lower" means the fish size data applies to the lower end only e.g. "fish exceeding 2 Kg are commonly taken in catches".
Rejected reason code
Some references have been excluded from the estimating process because they are judged to be unreliable. For example, there may be some ambiguity regarding the species they refer to. Whereas some references are not used because better references are available (i.e. ones with a higher reliability ranking), rejected references are NEVER used, regardless of what other references are, or aren't, available. While it could be argued that such references should not be included (i.e. visible) in the analysis, they are being displayed in order to give a full account of the method of processing references.
Reliability ranking of this method
This number indicates relative reliability of the method used in estimating the mean weight range from the fish size data. The lower this number, the better the data is likely to be.
EMW set to the min allowed value?
Set to "Y" where Lower (or upper) estimated mean weight (EMW) has been adjusted to the minimum allowed fish weight because they were originally lower than this minimum. In order to help address the risk of underestimating the mean weight for a species where less reliable methods are being used, a minimum fish size is used. This is the smallest fish size obtained by the most reliable method (i.e. where the reliability ranking is 1) and equates to 3.1g. Any estimated mean weight range which is partly or wholly less than 3.1g is adjusted to this value. This process helps to ensure that an unreliable figure doesn't excessively inflate our upper estimate for numbers of fish caught.
Size type
Additional information of the type of fish size data provided by this reference e.g. whether it corresponds to a market size; a commercial capture size or the size of fish caught in a survey. “Market size” references are generally only used if indicated to be for wild caught fish (or if the species is not indicated to be a farmed species on and if the weight given is a “whole round” weight.
EMW method type
The derivation of estimated mean weight ranges from different types fish size data are called "methods". Different methods require different types of calculation. For example, estimates based on common lengths require calculations to convert lengths to weights (using length-weight formulae). The type of method used depends on the type of fish size data being used and determines the reliability ranking of the reference.