60 U. S. BUREAU OF FISHERIES 
Fifty-three percent of the recovered lake trout were recaptured 
within 1 year of release; 73 percent within 25 miles from Port 
Washington. It required 3 years for the trout to become fairly well 
scattered throughout the lake. With the attainment of adulthood 
lake trout moved in all directions from the port of release, although 
nearly 50 percent of the adults were retaken within 25 miles from 
this port. 
Data are given on the growth and estimated age of the tagged 
lake trout, rainbow trout, whitefish, and sturgeon. Tt was found that 
the minimum size limits of lake trout and whitefish on the Great 
Lakes are economically unsound—they are too low—because they 
permit the capture of these species at the time of the most rapid 
increase in weight. 
AGE AND GROWTH STUDIES 
Saginaw Bay yellow perch—A study of the age and growth of the 
yellow nerch, Perca flavescens (Mitchill), of Saginaw Bay, by Dr. 
Ralph Hile and Mr. Frank W. Jobes, has been ‘completed and the 
first draft of the report prepared. Age determinations and computa- 
{ions of individual growth histories were made from the examination 
and measurement of the scales of 820 individuals collected in 1929 
and 1930. The investigation of the leneth-weight relationship was 
based on data from 1,483 specimens, and the ratio between total 
length and standard length was determined from measurements of 
1,411 fish. The report contains also a review of the statistics of the 
commercial production of perch in Saginaw Bay in the years 1891-1908 
and 1916-88. The average annual production in the years 1917-88 
has been only 28 percent of the 1891-1916 normal. 
The method of calculating growth from scale measurements, based 
on a study of the relationship between body lengths and the lengths 
(radi) of “key,” or selected scales from 512 fish, resembled that em- 
ployed earlier for the calculation of the growth of the Lake Erie 
perch. The use of direct-proportion ¢ calculations was found to be 
valid for all calculated lengths above 101 mm. Calculated lengths 
of 101 mm. and less had to be corrected (from an empirical curve of 
the body-scale relationship) to compensate the disproportionate 
erowth of body and scale in small fish. Both sexes of the Saginaw 
B day perch attain the legal length of 814 in. during the fourth year 
of life, just as they are entering on the period of most rapid ; growth 
in weight. Growth of females is shghtly more rapid than “males, 
both in length and in weight. The length-weight relationship (sexes 
combined) was described by the equation, W=0,.9826 x 10°Z221"4, 
where W=weight in grams and Z=standard length in millimeters. 
The ratio of standard length to total length was found to increase 
with the increase in the length of the fish. 
The Lake Michigan kiyi—tThe kiyi, Leucichthys kiyi Koelz, is one 
of two species of chubs inhabiting the deepest waters of Lake Michi- 
gan that practicably may be exploited with gill nets. During the 
Lake Michigan investigation of 1930-32, scale “samples, accompanied 
by data on length, weight, sex, and stage of maturity. were collected 
from 1,516 mdavicualle The scale samples, along with other data 
obtained during an analysis of the catches of experimental gill nets 
