Publications

More than 300 pairs of fine and coarse mesh plankton net samples were collected in the northern basin of Lake Chad during an 18-month period, June 1967 to November 1968. The seasonal distribution and abundance of the dominant species of Rotifera and Crustacea are given in addition to a general description of the hydrology and circulation of the northern basin of the lake. The composition and abund

Blood cell types of the sea lamprey, Petromyzon marinus, are described and identified and the lineage of mature circulating cells in peripheral blood is traced to blast cells in the hematopoietic fat body. The fat body appears to be the phylogenetic precursor of bone marrow in higher forms, since blood cells originate and begin maturation in this tissue. Experimental animals were injected first wi

Abstract has not been submitted

Periodid midwinter, early spring, and summer mortalities of alewives (Alosa pseudoharengus) have been common in the Great Lakes since the first appearance of the silvery marine invader in Lake Ontario in the mid-1870's. In 1967 a nationally publicized dieoff of tremendous magnitude (estimated at several hundred million pounds of fish) in Lake Michigan resulted in losses to industry,municipalities

Five female American brook lampreys, Lampetra lamottei, collected in lakes Michigan and Huron averaged nearly twice as long and about six times as heavy as American brook lampreys of normal size. Three factors suggested that the giant lampreys may have fed parasitically after metamorphosis: morphological adaptations of the species for parasitic life, their large size, and absence of extremely larg

Albinism in fishes is relatively rare except in some stocks of hatchery-reared salmonids. In the Petromyzonidae, only four albino lampreys have been reported.

Through a combination of ecosystem homeostasis and the perversity of man and nature, oftentimes the significant biological changes effected by environmental modifications are not detected until long after the initial change has taken place. The immediate impact, which may range from the spectacular to the undetectable, is a deceptive measure of the long-term and often more important changes in the

The movement of sea lampreys into the upper Great Lakes (Superior, Michigan, and Huron) initiated a series of biological changes which have extended beyond the fish directly attacked by the parasite. The threat posed by the sea lamprey was not generally recognized until it was well established in all the lakes and had seriously affected the fisheries in Lakes Huron and Michigan. As the sea lampr

Today's inland commercial fisheries are small independent operational units widely dispersed on lakes, impoundments, and streams throughout the vast central plains. The problems of the fisheries are diverse and unique to local conditions. Inland fisheries are particularly important to the Nation in times of international conflict because they are distributed throughout the area and the fish can

Lake herring eggs stripped and fertilized from a local stock were incubated in a constant-flow incubator at constant temperatures ranging from 0 to 12.1° C. Rate of development, percentage survival, percentage of abnormal and normal hatching, and length of fry at hatching were determined. The average incubation time from fertilization to 50% hatch varied from 37 days at 9.9-10.3° C to 236 days at

Salient features of the development of the industry from about 1815 to 1968, changes in fishing gears and methods, changes in the kinds and abundance of fishes caught, and the attendant effects of disappearing species on the stability of the fishery are described. The history and present status of the walleye, yellow perch, and eight other fishes, still taken in commercial quantities, are presente

The chemical 33NCS (3'-chloro-3-nitrosalicylanilide) was evaluated as a fish control agent and as a larvicide for sea lampreys at the Fish Control Laboratories of the Bureau of Sport Fisheries and Wildlife and the Hammond Bay Biological Station of the Bureau of Commercial Fisheries. The chemical is rapidly toxic to many species. Sea lampreys, bowfin, and channel catfish are the most sensitive spec