Geology Reports⌕ Search

Geology topics

Frank W. Jobes

Publications and source records attributed to Frank W. Jobes.

9 recordsLinked to original sources
USGS1949

The age, growth, and distribution of the longjaw cisco, Leucichthys alpenae Koelz, in Lake Michigan

The longjaw (Leucichthys alpenae) was found at all of the 109 stations fished in the open lake during 1930–1932 and at 29 of the 32 stations in Green Bay in 1930 and 1932. Koelz (1929) found the longjaw at 35 localities, 33 of which were different from those fished in 1930–1932. The species was most abundant in water with a depth of less than 70 fathoms, but was found as deep as 97 fathoms. The longjaw was estimated to be about 4 1/3 times as abundant along the east shore of southern Lake Michigan as along the west shore in 1930 and 1931. The abundance along the east shore in 1930–1931 was estimated to be approximately equal to that in northern Lake Michigan in 1932. The best explanation for the relative scarcity of L. alpenae along the west shore is that a more intensive fishery, with smaller sizes of mesh, was operating on a separate population. The length distribution of 6,954 specimens taken in 1930–1932 revealed little difference in frequencies between the sexes, the samples taken in each of the years 1930 and 1931, or the fish taken on the two shores of the southern region. The individuals caught in 1932 from northern Lake Michigan averaged 12.5 inches, total length, and were from 1.0 to 1.3 inches longer than fish taken by the same sizes of mesh from the southern area in 1930–1931. Of the 378 longjaws whose ages were determined, 320 were taken during the summer of 1923 in northeastern Lake Michigan, and 58 were secured off Grand Haven, Michigan, in November 1928. The age groups represented ranged from II to IX. Age-group IV dominated in the 1923 samples making up 53.8 percent of the total, and age-groups III and V with 20.9 and 10.6 percent, respectively, were the next best represented groups. The III group dominated the 1928 collection with 55.2 percent of the total, and age-groups IV and II, that were represented by 31.0 and 12.1 percent, respectively, were the only other well represented groups. The sexes grew at approximately the same rate. A total length of 11.1 inches and a weight of 6.4 ounces were reached at the end of 4 years of growth by the longjaws in northeastern Lake Michigan. The fish from Grand Haven averaged 11.0 inches, total length, and 6.1 ounces at the end of 4 years. Growth in length was most rapid during the first year and decreased continuously thereafter through the fourth year (fifth year in 1928). The increments in length of the 1923 fish during the fourth through the eighth years were approximately the same. Growth in weight of the fish taken in 1923 was computed to be most rapid following the fifth year of life. Growth compensation occurred among the longjaws of Lake Michigan. The major part of the annual growth in length had taken place before June 15, 1923. Although the empirical data on the length-weight relationship of 5,314 fish failed to fall along a simple curve, it is believed that the following equation is the one best suited to computing the weight of the longjaw: W = 0.96288 × 10 −5 L 3.06060 . The coefficient of condition (K) of all longjaws increased as the standard length increased to 194 millimeters. The values then remained high up to 225 millimeters but decreased progressively until the fish reached a length of 265 millimeters. The coefficient changed little at fish lengths of 265 to 284 but began to increase again at 285 millimeters. Condition was best in 1931 and poorest in 1932. The individuals of both sexes were in the poorest condition during some month previous to August each year. Although the females were somewhat heavier in relation to their length than the males in practically all months, the weighted averages of K for all males and all females were almost identical (1.30 for the males and 1.31 for the females). The sex ratio was determined from 7,457 individuals taken in 1930–1932 and 373 of the 1923 and 1928 specimens whose ages were determined. The percentage of females was relatively low in May 1931 and relatively high in October, but in the other months it remained more or less constant. In 1932 the females tended to become relatively less abundant in each month from April through September. There was little difference between the relative abundance of the sexes in 1930 and 1931 (72.4 percent females in 1930 and 67.5 percent in 1931). The consistently slightly higher percentage of females each month in 1932 (average of 80.6) probably represents a difference between populations. The relative abundance of the males decreased as the age increased. A natural differential mortality is suggested as the cause for the more rapid disappearance of the males. Females may contain ripe eggs as early as July 9, and some females may spawn as early as October 16 despite the fact that the spawning season is in November.

Transactions of the American Fisheries Society↗
USGS1946

The whitefish fishery of Lakes Huron and Michigan with special reference to the deep-trap-net fishery

This study of the whitefish fishery of Lakes Huron and Michigan includes: (1) a review of the available statistics of production, 1879-1942; (2) a detailed analysis of the annual fluctuations in the production and abundance of whitefish and in the intensity of the whitefish fishery in the State of Michigan waters of the lakes, 1929-1942, with special reference to the effects of fishing with deep trap nets; (3) an account of the bathymetric distribution and vertical movements of whitefish and certain other species; and (4) a report of field observations made in 1931 and 1932, as related particularly to the destruction of undersized whitefish by pound nets and deep trap nets. The main body of the manuscript and appendices A, B, and C, completed in March 1942, contain statistics through the year 1939. Since that time, records for the years 1940-1942 have become available. Because these additional data did not alter any of the conclusions of the manuscript but actually strengthened them, it was not deemed justifiable to expend the considerable amount of time and money that would be required to revise the study. The 1940-1942 records are therefore presented in appendix D. From a relatively high production in the earlier years of the period, 1879 to 1942, the yield of whitefish declined to a lower level about which the catch fluctuated until the late 1920's and early 1930's when a general increase in production occurred. This recent increase was higher and the subsequent decline more severe in the Michigan waters of Lake Huron than in other areas.

Lake Huron, Lake Michigan↗
USGS1941

Age, growth, and production of the yellow perch, Perca flavescens (Mitchill), of Saginaw Bay

Ages were determined and individual growth histories computed from the examination and measurement of scales from 820 yellow perch collected in 1929 and 1930. Calculated lengths greater than 101 millimeters were computed on the assumption (supported by empirical data) that the ratio of body length to scale length is constant. Lengths below 101 millimeters were determined with the aid of an empirical curve of the body-scale relationship of small fish. Yellow perch of age-groups III and IV (in the fourth and fifth years of life) made up the bulk of the collection (78 per cent). Females grew slightly more rapidly than males, but members of both sexes attained the legal length of 8 1/2 inches during the fourth year of life, just as they were entering on the period of most rapid growth in weight. The greatest growth in weight of both sexes occurred in the sixth year of life. In the combined samples of the two years the females exceeded the males in abundance in the ratio, 296:100. The weight of the Saginaw Bay yellow perch was found to increase as the 3.117 power of the length. The relative length of the tail decreased with increase in the length of the fish. The Saginaw Bay yellow perch is now far less abundant than it was in the early years of the fishery. The average annual production of 548,000 pounds over the period, 1917-1938, was only 28 per cent of the earlier (1891-1916) "normal" annual production of 1,961,000 pounds. A detailed analysis of statistical data available for more recent years made possible a description of annual fluctuations in the abundance and production of yellow perch and in the intensity of the yellow perch fishery in Saginaw Bay over the period, 1929-1938.

Transactions of the American Fisheries Society↗