Freshwater Fish Counts for all Species, all Areas and all Years - what does "run" mean?
A ‘Run’ is a fish removal. So for example, in an electric fishing survey a stretch of river will be netted off (with stop-nets), the stretch will be fished once, fish removed and recorded – that is Run 1.
Fish caught in Run 1 will not be returned to the stretch until all Runs have been completed. The stretch is then fished again, fish removed and recorded – that is Run 2, and so on.
So in the dataset you are looking at, the figures are the number of fish of that species caught in Run 1, Run 2, etc. All Runs gives you the total number of fish of that species caught in the survey (ie. Run 1, plus Run 2, plus Run 3 etc). The aim of doing the survey this way is to get a catch depletion which can then be used to get an estimate of the fish population size using the Carle & Strub population estimate method, the estimated population (where available) is also given in the dataset as SPCSNO.
For information, the 'Freshwater Fish Counts for all Species, all Areas and all Years' dataset has now been retired and replaced by the new Ecology & Fish Explorer , the datasets are the same within the explorer, but it allows you to select an area of interest on a map. So hopefully you’ll find it more user friendly. If you go to the ‘Documents’ tab in the Explorer, you will find a link to the fish surveys documentation which explains all the fields, including the Run fields.
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