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Bluegills Dominate Production in a Mixed Population of Fishes
Author(s) -
Cooper Edwin L.,
Wagner Charles C.,
Krantz George E.
Publication year - 1971
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934586
Subject(s) - population density , population , density dependence , stock (firearms) , thinning , biology , population growth , carrying capacity , ecology , growth rate , yield (engineering) , fishery , zoology , geography , mathematics , demography , sociology , materials science , geometry , archaeology , metallurgy
The effects of exploitation on growth, condition, and surplus production were measured over an 8—year period for a population of seven species of warm—water fishes in a 4.05—ha lake. The lake was shallow, fertile, and moderately productive. Population estimates of individual species were made each spring concurrently with the annual removal of 34% to 71% of the existing population. The initial stock density of all species was 48.66 g/m 2 in the spring of 1962. The optimum yield for this mixed population was calculated to be 14.56 g/m 2 per year at a stock density of 18.67 g/m 2 , with the bluegill producing most of this surplus weight. When species were considered separately, there was poor correlation between exploitation rate and either growth or condition. The response of the entire population to thinning was more predictable, with both growth and condition related to stock density. Best growth occurred at densities near 20 g/m 2 or approximately at the level for optimum yield.