Publications

Both State and Federal agencies have been working with the black-footed ferret and prairie dog during the past few years. Much of the work is not extensive enough for publication in scientific journals and is, therefore, not reported. The objective of this Workshop was to bring workers together for discussion of the current status of the two species. Each of the Conservation Departments in the sta

No abstract available.

The thermal regime of Lake Michigan is described on the basis of the analysis of 1,671 bathythermograph casts made in 1954 and 1955. The beginning, duration, geographic extent, and ending of thermal stratification were determined from 51 thermal profiles from all areas of the open lake. The lake gained heat for about 5 months (mid-March to mid-August) and lost heat over the rest of the year. It wa

Total and dissolved phosphorus, nitrate, and chlorophyll a were measured at four stations in northern Lake Michigan (inshore Michigan, offshore Michigan, offshore Wisconsin, and inshore Wisconsin) and one station in southern Green Bay during 16 sampling periods in 1965. The nutrients were measured at depths of 2, 5, and 10 meters and chlorophyll a at 2 meters. In Green Bay total phosphorus (33.7 p

Black duck (Anas rubripes) hens fed 10 ppm dry weight (approximately 3 ppm wet weight) of p,p'-DDE in the diet laid eggs with shells 22 percent thinner at the equator, 30 percent thinner at the cap, and 33 percent thinner at the apex than those of controls. Natural incubation increased shell cracking more than fourfold as compared with mechanical incubation. Hens removed cracked eggs from nests, a

Reproductive performance was measured for 126 days in twelve pairs of ring doves (Streptopelia risoria) fed a diet containing 40 ppm of p,p'-DDE and in twelve other pairs given untreated food. The DDE-treated doves took an average of 2 1/2 times longer to renest than controls, produced 13·5% fewer eggs/clutch, had 10% thinner eggs, and experienced twice as great mortality of young; all these diffe

Back-mounted radio packs of three weights were attached to 30 captive mallards (Anas platyrhynchos) and 30 blue-winged teal (A. discors), and physical condition of the birds was evaluated for 12 weeks. All groups with radio packs lost more weight than did control groups. Feather wear often followed by skin irritation occurred in the axillary region of the wings on 90 percent of the treated birds w

The current widespread presence of chlorinated insecticides, polychlorinated biphenyls (PCB's) and herbicides in world waterways has elicited much interest in the mechanisms of their toxicity in fishes. Inhibition of Na+,K+-activated adenosinetriphosphatase (NaK-ATPase) and Mg++-dependent ATPase (Mg-ATPase) by DDT, endosulfan and dicofol has been demonstrated in gill, brain and kidney microsomes o

A night vision scope was used during 1969-71 to study the nighttime feeding behavior of ducks on prairie wetlands of south-central North Dakota. Adult and immature ducks were observed feeding between 9:00 PM and 4:00 AM, predominantly on midges (Chironomidae) and mayflies (Ephemeroptera). The emergence pattern of these insects appeared to be a major factor influencing duck activity and feeding beh

The histopathogenesis of infectious haematopoietic necrosis (IHN) virus infection was studied by exposing juvenile sockeye salmon (Oncorhynchus nerka) to the IHN virus. Fish samples were taken every 24 h for histological examination and for determination of virus concentration. A close correlation was found between histopathological changes and virus concentration. The most significant changes occ

Abstract not submitted to date

In no other lake as large as Lake Erie (surface area, 25,690 km2) have such extensive changes taken place in the drainage basin, the lake environment, and the fish populations over the last 100 years. Deforestation and prairie burning led to erosion and siltation of valuable spawning grounds. Marsh spawning areas were drained. Lake-to-river spawning migrations were blocked by mill dams. Accelerate