Fish habitat mapping using acoustic and GIS technologies.

摘要

A rapid and accurate the method of assessment for fish habitats is a growing need as there is increasing degradation of aquatic environments world wide. While several small Canadian companies have developed useful technology to assess fish habitats, their ability to manage and integrate data into geographic information system (GIS) is limited. The first objective of this thesis was to evaluate the methods for undertaking and assessing the acoustic classification of substrates for five freshwater systems ranging from a prairie river (Red River), to a Canadian Shield river (Winnipeg River), to a northern Canadian river (Mackenzie River), to small northern and Arctic lakes (Chitty Lake and Wormy Lake using a QTC VIEW(TM) and a QTC IMPACT(TM) (a package of hardware and software made by Quester Tangent Corporation). The Red River has few major substrate classes while the Winnipeg River has more numerous, rapidly changing, small-scale substrate patterns. The Mackenzie River, on the other hand, is a large river with large-scale homogeneous substrates allowing for the collection of many acoustic signals from one substrate type and making the correlation of acoustic signal and substrate classes easier. Ground truth was undertaken by collecting benthic samples and developing a "visual classification system" and a process for the separation of sediments based on grain-sizes and proportions. A geographical information system (GIS) was developed in which the acoustic data were used to interpolate into continuous bathymetry and substrate patterns. The second objective was to determine if a comprehensive catalogue of substrate classes could be developed, to correlate them with the benthic samples, and to relate the bathymetry models and the substrate classes to fish movements, i.e. lake sturgeon, Acipenser fulvescenes, lake trout Salvelinus namaycush and Arctic char Salvelinus alpinus, in a spatial context. To expand the understanding of substrate, the track points of lake sturgeon movements were superimposed on interpolated maps of the bathymetry and the substrate patterns at the Seven Sisters site on the Winnipeg River. The movements of lake sturgeon, lake trout and Arctic char were tracked in the three systems using a VEMCO's acoustic telemetry system. Additional selected samples of lake trout and Arctic char movement records (two fish of each species from each site) were assessed to verify the association of the fish movement and the substrate maps developed from the acoustic data from Chitty Lake and Wormy Lake. The frequency of occurrence over certain substrate types will help biologists define fish habitats.; It is recommended that (1) the acquisition of high resolution data from the QTC VIEW be accomplished by reducing the boat speed and decreasing the distance between transects to determine if the acoustic signal is more variable from complex substrates and (2) for studies on fish movements reduce battery power of acoustic tags to limit the detection range by VR2 receivers and thereby improve resolution.