Premium
Influence of Fish Density and Relative Productivity on Growth of Kokanee in Ten Oligotrophic Lakes and Reservoirs in Idaho
Author(s) -
Rieman Bruce E.,
Myers Deborah L.
Publication year - 1992
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(1992)121<0178:iofdar>2.3.co;2
Subject(s) - oncorhynchus , intraspecific competition , productivity , density dependence , population density , trophic state index , fish migration , hydrobiology , primary productivity , fishery , competition (biology) , biology , fish <actinopterygii> , ecology , eutrophication , environmental science , population , nutrient , aquatic environment , economics , macroeconomics , demography , sociology
We used 28–48 observations from 10 oligotrophic lakes and reservoirs to describe the influence offish density and relative aquatic productivity on growth of kokanee Oncorhynchus nerka . We found a positive relationship between length at age at all ages and an index of lake or reservoir productivity. We found evidence of strong density dependence for older fish (ages 2 and 3), but not for yearlings (90–210 mm total length). The density‐dependent response in growth was of a decaying exponential form. We found a significant interaction (Secchi transparency × density) that indicated the general response of growth to density was more pronounced in waters of lower productivity. Density dependence may thus be more obvious in populations fluctuating at low density or in unproductive waters than in populations at higher densities. Intraspecific competition probably increases with age and size and probably is not important among age‐0 or age‐1 fish at the densities observed (< 1,000 fish/hectare). The form of the density‐dependent growth response we observed for kokanee was different from that described for some populations of sockeye salmon, the anadromous form of O. nerka . Mechanisms of population regulation for the two forms probably differ as well. Our empirical models of growth should be useful to managers interested in density‐related changes in fisheries of oligotrophic waters.