| Summary: | Lake trophy and fish population characteristics were studied in two small saline lakes in southwestern Manitoba during the 1978 and 1979 open-water periods. Greater eutrophy in St. Dalmas Lake (area = 61.3 ha; T.D.S. = 2183 mg.1 -1) compared to S. Thomas Lake (area = 79.2 ha; T.D.S. = 1390 mg.1 -l) was related to highly localized edaphic conditions. A higher mean annual chlorophyll-a concentration and zooplankton biomass was observed in St. Dalmas. Consistent with lake trophic differences, the pooled abundance or biomass of the principal fish species in St. Dalmas (yellow perch Perca flavescens, and walleye Stizostedion vitreum vitreum) was greater than that of those in S. Thomas (northern pike Esox lucius, yellow perch and walleye). Perch predominated in both lakes, but their relative abundance and biomass was greater in St. Dalmas. Mark and recapture experiments showed greater walleye biomass (10.7 kg/ha) in St. Dalmas than the biomass of either S. Thomas walleye (0.9 kg/ha) or pike (5.5 kg/ha). These estimates are comparable to mean values reported for non-saline lake populations. A more diverse piscine community was observed in S. Thomas...
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