The file electrofishing.csv contains the data on sea trout captures by electrofishing in the mouth of the river Shieldaig. These data are used to construct metrics of sea lice infestation pressure in the paper A 20-year study examining the effects of salmon lice on the return rate, time at sea, and marine growth of sea trout migrating from the river Shieldaig in Scotland.
The file is UTF-8-BOM encoded so can be read directly into Excel, or into R using the function read.csv with the argument fileEncoding = “UTF-8-BOM”.
The variables in the file are:
date
Description: the date the trout was caught
Unit: YYYY-MM-DD
Type: date
Range: 1999-05-11, 2019-06-26
Note:
year
Description: the year the trout was caught
Unit: y
Type: discrete
Range: 1999, 2019
Note:
month
Description: the month the trout was caught
Unit:
Type: categorical
Levels: May, June
Note:
day
Description: the day of the year (from 1 January) that the trout was caught
Unit: d
Type: discrete
Range: 122, 180
Note:
fish
Description: identifier of each trout
Unit:
Type: categorical
Levels: 804
Note: some trout were not tagged so have no identifier
length
Description: the length of the trout
Unit: mm
Type: continuous
Range: 104, 386
Note:
weight
Description: the weight of the trout
Unit: g
Type: continuous
Range: 14, 600
Note: not measured in 1999, 2000, 2006, 2007, 2008
attached
Description: the number of attached (copepodid / chalimus) lice on the trout
Unit: n
Type: integer
Range: 0, 500
Note: when counting would be overly time-consuming, a ballpark estimate of 100, 200, or 500 was recorded to prevent the trout from being under anaesthetic for too long; measured from 2002 onwards
mobile
Description: the number of mobile (pre-adults or adults excluding ovigerous females) lice on the trout
Unit: n
Type: integer
Range: 0, 157
Note: measured from 2002 onwards
ovigerous
Description: the number of ovigerous female lice on the trout
Unit: n
Type: integer
Range: 0, 3
Note: measured from 2002 onwards
presence
Description: whether the trout had any lice
Unit:
Type: logical
Levels: TRUE (33%), FALSE (67%)
Note:
threshold
Description: whether the total number of mobile lice on the trout met or exceeded the threshold for harm
Unit:
Type: logical
Levels: TRUE (24%), FALSE (76%)
Note: the threshold for harm was 13 mobile lice; the total number of mobile lice on the trout was calculated as 0.63 x attached + mobile + ovigerous, where the factor of 0.63 accounts for the survival of attached lice to the mobile stage; available from 2002 onwards
include
Description: whether the capture was used in the calculation of the sea lice infestation pressure metrics
Unit:
Type: logical
Levels: TRUE (96%), FALSE (4%)
Note: when a trout was captured more than once in a particular year, the capture with the greatest total number of mobile lice was used; in the event of a tie, the latest capture was used