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Seasonal variability in the abundance of Arctic charr ( Salvelinus alpinus (L.)) recorded using hydroacoustics in Windermere, UK and its implications for survey design
Author(s) -
Winfield I. J.,
Fletcher J. M.,
James J. B.
Publication year - 2007
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/j.1600-0633.2006.00170.x
Subject(s) - salvelinus , abundance (ecology) , arctic , sampling (signal processing) , fishery , ecology , environmental science , geography , biology , trout , fish <actinopterygii> , engineering , filter (signal processing) , electrical engineering
– Hydroacoustic surveys are an important tool for assessing the abundance of Arctic charr ( Salvelinus alpinus (L.)) in lakes, the requirement for which is increasing because of new environmental legislation. Consequently, survey demand is now such that assessments must be undertaken with the minimum of effort compatible with scientific validity. One major complication is seasonal variability in abundance, with which surveyors have attempted to deal by defining somewhat arbitrary seasonal sampling windows. The definition of more objective windows was pursued by analysing variations in the seasonal abundance of Arctic charr in Windermere, UK, recorded using day and night hydroacoustic surveys at monthly intervals from 1991 to 2001. Two alternative sampling windows for night surveys free of significant internal seasonal effects were revealed, i.e., December to September and September to December. It was also found that day surveys gave a useful, although lower, estimate of abundance as compared with night surveys.