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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



short spawning season. It seems likely, however, 

 that the longer periods of spawn taking closely 

 approximate the spawning season. 



It appears that the lake-trout spawning season 

 lasts from 10 to 20 clays in the smaller New York 

 lakes and the duration is fairly uniform in the 

 same lake from year to year. The lake trout of 

 Lake George consistently completed their spawn- 

 ing in 7 to 10 days at the most. 



The length of the spawning season increases 

 in the larger lakes. Van Oosten (1935) gives the 

 duration of the spawning season in Lake Michigan 

 as October 10 to November 21; in Lake Huron, 

 October 10 to November 15; and in Lake Superior, 

 October 1 to November 6. Seneca Lake is 

 similar to the Great Lakes in both date and 

 duration of the spawning season. The earliest 

 and latest dates on which the New York State 

 Conservation Department obtained eggs in Seneca 

 Lake were September 23 and November 3. These 

 dates are for difTerent years, but the earliest and 

 latest dates were similar from year to year. 



PLACE OF SPAWNING 



The observations of Merriman (1935), Royce 

 (1936), and the writer indicate that lake-trout 

 spawning areas are restricted to bottom of clean 

 gravel or rubble, free of sand and mud. As the 

 fish make no effort to bury the eggs, the bottom 

 must have crevices into which the eggs can roll, 

 if eggs and larvae are to be protected. 



The location of these suitable areas of bottom 

 in the lake is primarily determined by currents 

 or wave action which keep the bottom swept clean. 

 The lake trout will roll the smaller stones around 

 and fan oflF the silt, but they cannot remove sand 

 or mud from the crevices. Any bottom that is 

 not swept by currents or waves eventually becomes 

 covered with mud, although in the usual oligo- 

 trophic lake-trout lake this process would take a 

 very long time. 



In the littoral zone, the width of the area of 

 clean rocks or sand is dependent directly on the 

 size of the lake and its exposure to the wind. In 

 the smaller New York lakes the lake trout general- 

 ly may be found spawning by windy points near 

 deep water (Royce 1936), on bottom kept clean 

 by the waves. A typical example of such shallow- 

 water spawning is to be found in Otsego Lake. 



In larger lakes the lake trout may go to deeper 

 water for their spawning. Milner (1874) reports 

 that the lake trout in Lake Superior spawn in 

 7 feet to 15 fathoms of water. Evidence of 

 spawning in the deep water was provided by the 

 capture of ripe fish at that depth and by raising 

 in the nets fragments of honeycombed rocks 

 containing eggs. In Seneca Lake the lake trout 

 are captured for stripping in 100 to 200 feet of 

 water at a time when no lake trout are found in 

 shallow water. The fact that ripe lake trout 

 are captured over bottom that is suitable for 

 spawning is strong evidence that the trout 

 actually are spawning at these depths. Further 

 proof was provided by the capture on the spawning 

 bed in Seneca Lake, in April 1940, of a lake-trout 

 fry 25 millimeters in total length, in water 130 

 feet deep. 



There is much evidence that these deeper 

 spawning areas are swept by strong currents. 

 The hatchery fishermen reported that their nets 

 were often rolled over and over by the currents 

 in Seneca Lake. In this same lake off Peach 

 Orchard Point the 40° F. isotherm rose from a 

 depth of 260 feet on September 29, 1941, to 100 

 feet on October 1 after a strong south wind; 

 on October 7 it was back down to a depth of 230 

 feet. Such a change must be accompanied by 

 the movement of a huge quantity of water. 



These currents in Seneca Lake and the other 

 Finger Lakes have left evidence of a prevailing 

 direction of flow. All these lakes are very long 

 and narrow and lie with their long axes in very 

 nearly a north-south direction. Seneca Lake is 

 the largest, being about 40 miles long and 3 miles 

 wide at its widest point. The prevailing winds 

 come from the northwest or the southeast, blow- 

 ing obliquely to the south on the eastern shore 

 and obliquely to the north on the western shore 

 of the lake. The general result has been to form 

 the tips of deltas to the south of the stream mouths 

 on the eastern shore of the lake and to the north 

 of the stream mouths on the western shore. 



In addition to the characteristic orientation of 

 the deltas, there is a definite gradation in the size 

 of the material deposited in the various parts of 

 the delta. Off the tip of Peach Orchard Point in 

 Seneca Lake down to a depth of at least 300 feet, 

 only clean gravel and rubble could be found with 

 a clamshell dredge, or seen in bottom photo- 



