Skip to main content

LaRue Wells

thumbnail
Lake Michigan surface area is 22,400 square miles and its main depth is 276 ft. Its fauna is generally typical of North American oligotrophic lakes. The original fish populations included 10 coregonines and one salmonine. The lake whitefish, the lake herring, and the lake trout were most abundant. Man's activities have caused great changes in the lake in the past 120 years. Although changes in water chemistry and in the lower biota have been generally modest (except locally), those in salmonid communities have been vast. Exploitation, exotic fish species (especially the sea lamprey and alewife), and accelerated eutrophication and other pollution, all have played a role in bringing about the modifications (mostly...
thumbnail
Lake trout were collected in graded-mesh gill nets and forage fishes were collected in trawls in mid December 1981 and late March 1982. The length ranges of 317 lake trout caught in December and 138 in March were 280-767 and 286-857 mm, and the age ranges I-XI and II-XIV, respectively. Three year classes (1977-79) made up almost 80% of the catches of lake trout in both sampling periods. Lake trout were most abundant at depth of 18 to 37 m in December (water temperatures, 5.5-6.8A?C) and at 2864 m in March (water temperatures, 1.0-1.3A?C). Fish of the 1977-79 year classes completed 9 to 24% of their annual growth in length, and 14 to 39% of their growth in weight, between mid December and late March. Lake trout ate...
thumbnail
The vertical migration of the amphipod Pontoporeia affinis in Lake Michigan has been well documented by Wells, Marzolf, and McNaught and Hasler. Wells and Marzolf observed Pontoporeia off bottom only at night. McNaught and Hasler, however, found Pontoporeia above the bottom shortly after noon in a 24-hr study on 12 June 1965, and some individuals were taken just below the thermocline in all daylight hours in a similar study on 19-20 August. This paper presents evidence that Pontoporeia regularly were present above bottom during the day from April-August 1964. The data for this report were collected during a study of seasonal and depth distribution of larval bloaters (Coregonus hoyi) in Lake Michigan. Sampling was...
Categories: Publication; Types: Citation; Tags: Limnology and Oceanography
thumbnail
The zooplankton populations in southeastern Lake Michigan underwent striking, size-related changes between 1954 and 1966. Forms that decline sharply were the largest cladocerans (Leptodora kindtii, Daphnia galeata, and D. retrocurva), the largest calanoid copepods (Limnocalanus macrurus, Epischura lacustris, and Diaptomus sicilis), and the largest cyclopoid copepod (Mesocyclops edax). Two of these, D. galeata and M. edax (both abundant in 1954), became extremely rare. Certain medium-sized or small species increased in numbers: Daphnia longiremis, Holopedium gibberum, Polyphemus pediculus, Bosmina longirostris, Bosmina coregoni, Ceriodaphnia sp., Cyclops bicuspidatus, Cyclops vernalis, and Diaptomus ashlandi. Evidence...
Categories: Publication; Types: Citation; Tags: Limnology and Oceanography
thumbnail
Data collected during successive years (1971-79) of sampling lake trout (Salvelinus namaycush) in Lake Michigan were used to develop statistics on lake trout growth, maturity, and mortality, and to quantify seasonal lake trout food and food availability. These statistics were then combined with data on lake trout year-class strengths and age-specific food conversion efficiencies to compute production and forage fish consumption by lake trout in Lake Michigan during the 1979 growing season (i.e., 15 May-1 December). An estimated standing stock of 1,486 metric tons (t) at the beginning of the growing season produced an estimated 1,129 t of fish flesh during the period. The lake trout consumed an estimated 3,037 t...
Categories: Publication; Types: Citation; Tags: Technical Paper
View more...
ScienceBase brings together the best information it can find about USGS researchers and offices to show connections to publications, projects, and data. We are still working to improve this process and information is by no means complete. If you don't see everything you know is associated with you, a colleague, or your office, please be patient while we work to connect the dots. Feel free to contact sciencebase@usgs.gov.