The Age and Rate of Growth of the Sheepshead, Aplodinotus Grunniens Rafinesque, in the Upper Mississippi River Navigation Pools
- 1 January 1950
- journal article
- Published by Oxford University Press (OUP) in Transactions of the American Fisheries Society
- Vol. 79 (1) , 43-54
- https://doi.org/10.1577/1548-8659(1949)79[43:taarog]2.0.co;2
Abstract
This study is one of a series of studies made of the fisheries of the upper Mississippi River as part of the program of the Upper Mississippi River Conservation Committee. The scale method was validated for the species and growth rates were calculated. Latitude was not a factor in the growth of 902 sheepshead taken from navigation pools 4A, 8, 10, and 17. Growth rates within different areas of the same pool and from pool to pool were sufficiently alike so that the growth from Lake Pepin to Muscatine, Iowa, can be considered uniform. Sheepshead from the upper Mississippi River grow more rapidly than those of Lake Erie. Average growth for the first year was 4.9 inches followed by a 4.0 inch growth during the second year. At the end of the seventh year they had reached a total length of 18.1 inches, 2.3 inches longer than 7‐year‐old sheepshead from Lake Erie. Annual growth rates observed for the period 1939 through 1947 were 7.8 percent above the average in 1939 and 7.3 percent below average growth during 1945. No relationship existed between growth rates and average annual water levels. During the third year of growth 23 percent of the males reach maturity. The first mature females were observed during their fifth year. Growth rates of earliest maturing males and females were far above average. Management implications of these investigations of the sheepshead are (1) the uniformity of the growth pattern requires uniform regulations in the area studied and (2) maintenance of spawning stock is dependent on adequate survival of 16‐inch females, the length at which more than 50 percent of the females are mature.This publication has 0 references indexed in Scilit: