Premium
Observations on Mortality Rates in Fished and Unfished Cisco Populations
Author(s) -
Miller Richard B.
Publication year - 1950
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(1949)79[180:oomrif]2.0.co;2
Subject(s) - fishing , mortality rate , square (algebra) , population , fishery , geography , environmental science , oceanography , demography , biology , geology , mathematics , geometry , sociology
Square Lake, Alberta, has an area of 2.5 square miles and possesses a dense cisco population which has not been fished. Baptiste Lake, area 8 square miles, has a cisco population which has been fished, and Lesser Slave Lake, area 462 square miles, possesses a cisco population which has been at first lightly, then heavily fished. Catch curves from these lakes are compared and mortality rates calculated. It is shown that the mortality rate in an unfished lake may exceed the total mortality rate in a lightly fished lake. The suggestion is made that natural mortality rate is influenced by fishing mortality rate. It is further argued that predictions of the course of a fishery based on catch curves must be made with great caution due to large unpredictable changes in rate of recruitment which follow changes in fishing intensity.