Showing papers in "CTIT technical reports series in 1969"

The ecology and management of the walleye in western Lake Erie

Abstract: Map of Lake Erie showing key geographic and cultural features. (Adapted from various U. S. Corps of Engineers charts.) FOREWORD The public agencies responsible for the management of the fisheries in western Lake Erie have been concerned for many years by the violent instability of the fish resources and the succession of species that have become either economically insignificant or biologically extinct. These problems have also drawn the attention of a number of international commissions. Not once have these efforts led to a common management approach by the various governments with responsibility in this area. Short-run self-interest appears to have blocked cooperation to the ultimate disadvantage of all users. Concern became acute, a decade ago, with the collapse of the population of the walleye-a species that was then not only the most valued one to commercial and sport fishermen but also the last of the \" high value \" fishes remaining in the lake. Research programs were begun, fishermen were interviewed, fishery experts consulted, but no common agreement could be reached as to the cause or causes of the changes in the fish populations or the kind of concerted action that might be taken to improve matters. The report that we present here is a reasonably comprehensive summary of information bearing on the problem of the walleye in western Lake Erie. The information is organized to permit evaluation of all the major hypotheses that have been suggested recently as explanations for the observed fluctuations in the walleye population. Those hypotheses that we believe to be correct are identified and presented in a conceptual framework that we hope will be useful not only for the purpose of current management of the resource but also as a guide for future research. We are aware of the existence of data relevant to the problem of the wall-eye in western Lake Erie that still have not been analyzed from the standpoint of the views proposed here; when these data and new information are evaluated we expect that some of our present inferences and judgments will be found to be incorrect or, at least, inadequate. Nevertheless, we present this analysis with confidence as an adequate basis for the much needed management decisions that are required at this time if the walleye resource of western Lake Erie is to be preserved. In acknowledging here a special indebtedness to a number of persons for data, observations and …

Planktonic diatoms of Lake Ontario

Abstract: Records are presented of Na+, K+, Ca++, SiO,, pH, alkalini ty, 0, , and specific conductance at 106 stations in Lake Ontario. These data are compared for east-west and surface-subsurface variations. Water quality in Lake Ontario is similar to that in Lake Erie with the exception of dissolved oxygen. The open waters of Lake Ontar io had no areas of serious oxygen depletions.