Michigan Department of Natural Resources
Fisheries Research Report No.1813, 1974

Estimates of Biomass of Principal Fish Species in the Great Lakes (First Report)

G. P. Cooper, p.. 2.


Lake trout in Lake Michigan,

R. W. Rybicki and Leon Moffit, p.. 5.


Whitefish in Lake Michigan,

M. H. Patriarche,, p.. 15.


Alewives and chubs in Lake Michigan,

E. H. Brown, Jr., p.. 21.


Lake herring in Lake Superior,

J. W. Peck, p.. 27.


       Abstract.-Estimates of biomass of selected fish species were made for specified years and for designated portions of Lakes Michigan and Superior. Estimates for alewives and chubs were based on trawl catches per unit of area, multiplied by total area occupied by the species. For lake trout, herring and whitefish, annual mortality rates were related to known recruitment (lake trout of hatchery origin) or to variable catch per unit of effort of commercial gear over a period of years. Standing crop estimates are:

Lake trout, Michigan waters of Lake Michigan, 1972, 11. 2 million pounds, in age-groups II and older.

Whitefish in northern Lake Michigan, 1971 and 1972: Those in age-groups III and older, and subject to commercial exploitation, 4. 4 and 6.6 million pounds, respectively. Including age-groups I and II, and all age groups in MM2 (closed to fishing), total biomass was 33 and 55 million pounds, respectively.

Alewives, all of Lake Michigan but limited to the zone of bottom trawling, fall of 1973, 220 million pounds, of age-groups I and older. Expansion of this estimate, to include fish in midwater, gives up to a 10-fold increase in the total figure, i. e., up to 2 billion pounds.

Chubs, all of Lake Michigan, fall of 1973, 15 million pounds, of age-groups I and older.

 Lake herring, Michigan waters of Lake Superior, in 1972, for only those herring grounds which were fished commercially during 1972, 4 million pounds of fish in age-groups V-VIII (fish of commercial size). Confidence limits and other limitations of these estimates are discussed.