Publications

Samples of flesh were excised from the middorsal region of 67 siscowets (Salvelinus namaycush siscowet) and 46 lake trout (Salvelinus n. namaycush) collected from Lake Superior. Chemical analysis of the samples revealed a range in fat content (dry weight) of 32.5 to 88.8 per cent in siscowets and 6.6 to 52.3 per cent in lake trout. Percentage fat increased progressively with increase in length of

Instances of thermal stratification have been detected only occasionally in western Lake Erie during the past 40 years, but when it does occur it is of considerable importance because of associated dissolved oxygen (DO) depletion in the hypolimnion. Data collected in June of 1963 give an indication of the meteorological conditions necessary to produce this thermal stratification. These conditions

Stomachs were examined from 1,492 lake trout and 83 siscowets collected from Lake Superior. Data are given on the food of lake trout of legal size (17 inches or longer) by year, season, and depth of water, and on the relation between food and size among smaller lake trout. Fish contributed 96.7 to 99.9 per cent of the total volume of food in the annual samples. Ciscoes (Coregonus spp.) were most c

Lakes Huron, Michigan, and Superior are classified as oligotrophic lakes on the basis of their biological, chemical, and physical characteristics. Lake Ontario, although rich in nutrients, is morphometrically oligotrophic or mesotrophic because of its large area of deep water. Lake Erie, the most productive of the lakes and the shallowest, is eutrophic. Several changes commonly associated with eut

The northern pike is one of Ohio's largest game fish but is well known to comparatively few anglers. Large numbers of the big fish spawn in the Ohio marshes adjacent to Lake Erie. Movements related to spawning reach a peak in late March or early April. Later the spawning population disperses and is seldom represented in catches by experimental gear or by anglers. The short period of availability w

The sex, length, and weight were determined of nearly all recently transformed sea lampreys migrating downstream in the Carp Lake River, Michigan, in the fall, winter, and spring of 1960-61. Similar data were collected from samples of an earlier run in the Carp Lake River and of runs in three other tributaries of Lakes Huron and Michigan. The sex ratio of the 1960-61 migrants in the Carp Lake Rive

The successful stocking of the hatchery-reared lake trout (Salvelinus namaycush) in Lake Superior has imporved the outlook for rehabilitating stocks reduced to an extremely low level by predation from the sea lamprey (Petromyzon marinus). Marking the fish by fin-clipping to determine growth and survival benefits from holding young-of-the-year lake trout in the hatchery overwinter was begun in 1952

Experimental sea lamprey control by the Bureau of Commercial Fisheries on Lake Superior streams provided many new distributional records of the fish fauna. Seventy-one species were recorded from 175 streams. Specimens were collected at the electromechanical barriers, with electric shockers, with fyke nets, and during chemical treatment of streams. Maps showing stream records of each species are pr

No abstract available.

The history of fish diseases in western United States shows an increasing awareness that viruses could cause epizootics in fish. Fishery biologists bunked first, for protozoan and metazoan parasites, then for bacteria, and if none could be identified assumed that the mortalities were attributable to nutritional deficiency, Microbiologists in general were cognizant of virus diseases in other animal

Rainbow trout were fed a pelleted diet containing killed cells of the etiologic agent of a bacterial disease, redmouth. These fish in addition to appropriate controls were subsequently challenged with virulent homologous organisms. Ninety per cent of the redmouth immunized fish survived the basic challenge using virulent organisms in contrast to 20% survival for the controls. Multiple challenge do

An exogenous strain of cultured Hexamita salmonis (Moore) was employed to induce trophic hexamitiasis in otherwise disease-free juveniles of coho salmon (Oncorhynchus kisutch) and steelhead trout (Salmo gairdneri). Mortality and growth were the parameters used to detect the effects of hexamitiasis on the two species. Two levels of each of the three experimental factors under study, Hexamita infect