Habitat 



All of the lakes in which the presence of pygmy smelt has been verified, are small, deep 

 and thermally stratified in summer. Lake Heney is an oligotrophic lake about 9 km long, 

 1250 hectares, has an average depth of about 18 m and a maximum depth of 35 m. In June the 

 thermocline extends from about 2 to 3 m. The Secchi disk reading varies from about 3 to 

 6 m. The mean pH in Heney Lake in 1966-67 was 7.3. The lake freezes over from 8-28 

 December and break-up occurs from 23 April to 1 May (all preceding details from Delisle, 

 1969a). Wilton Pond, Maine is approximately 4 km long, Green Lake, Maine about 9 km, and 

 Lake Utopia, New Brunswick about 8 km long. So all lakes in which pygmy smelt are 

 definitely known are small, 9 km or less in length. 



The following details on Lake Utopia are drawn from data in the files of the Fish and 

 Wildlife Branch, New Brunswick Department of Natural Resources, through the courtesy of 

 Mr. Peter Cronin. The surface area is 1370 hectares, the mean depth 11.05 m, the maximum 

 depth 25.6 m, the morpho-edaphic index 0.94, the pH 7 at the surface, 6.7 at 11 m, and 6.4 

 at 26 m. On 27 August 1969 the thermocline was located between 10 and 15 m depth, and on 

 3 July 1969 the surface temperature was 19 and the bottom at 25 m was 7.8 degrees C. 



Rainbow smelt are known in lakes large and small, although most are probably deep and 

 thermally stratified in summer. Lake Champlain which might contain both species is about 

 130 km in length. Lake Superior into which rainbow smelt have been successfully introduced, 

 is more than 500 km long. Many rainbow smelt populations are anadromous and live in the sea 

 after hatching until as adults they run up streams and rivers to spawn in spring. 



The following additional notes on habitat and movement are drawn from Delisle's (1969a) 

 valuable thesis. Young-of-the-year pygmy smelt, but not rainbow smelt, aggregate in shallow 

 water near sand and gravel beaches in July, August and winter. In July pygmy smelt adults 

 migrate up into the epilimnion (21 degrees C) from the bottom in the hypolimnion (7-9 

 degrees C) , at 2300 to 0200 hours. The adult pygmy smelt was found to form schools beneath 

 the ice in January. 



Before spawning in April, pygmy smelts migrate from the depths to the surface between 

 0100 and 0400 hours. The rainbow smelt was found throughout the year in the deeper southern 

 basin of the lake, except at spawning time, and was not observed to make vertical migrations 

 or be attracted to lamps at night. 



The evidence suggests that there are habitat and behavioral differences between pygmy and 

 rainbow smelts. That separation is not complete, however, is attested by the presence of 

 pygmy smelts in the stomachs of rainbow smelts. 



TRANSPLANTATION EXPERIMENTS 



Transfer of species from one lake to another lake with differing conditions may assist in 

 determining if taxonomic characters have a genetic base. 



In 1912 rainbow smelt from Green Lake, Maine, were transplanted into Crystal Lake, 

 Michigan. From there the smelt spread into each of the Great Lakes. Despite marked 

 temperature and productivity differences between lakes Superior and Erie, populations from 



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