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Selective Predation by Pelagic Arctic Char on Crustacean Plankton in Takvatn, Northern Norway, before and after Mass Removal of Arctic Char
Author(s) -
DahlHansen Geir A. P.,
Rubach Stein H.,
Klemetsen Anders
Publication year - 1994
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1994)123<0385:spbpac>2.3.co;2
Subject(s) - pelagic zone , arctic char , crustacean , plankton , predation , char , arctic , oceanography , environmental science , the arctic , ecology , fishery , biology , geography , geology , fish <actinopterygii> , trout , salvelinus , coal , archaeology
Arctic char Salvelinus alpinus once occurred at high densities in the pelagic zone of Takvatn. An intensive fish stock reduction program begun in 1984 reduced the catches of pelagic Arctic char by approximately 60% from 1981 to 1986. The crustacean plankton was dominated by Bosmina longispina , Cyclops scutifer , and Eudiaptomus graciloides . With the exception of a density increase of B. longispina , only minor changes were found in the density and species composition of the zooplankton after the stock reduction. Terrestrial insects and crustacean plankton dominated the diet of pelagic Arctic char in both 1981 and 1986. Cyclops scutifer was positively selected in June and July of both seasons. Following the density increase of B. longispina , this species was strongly selected in August–September. Other zooplankton species were either avoided or randomly selected.