FISHES OF DOUGLAS L.^KE, MICHIGAN. 

 Table III. — Records of Esox luciu.s Taken in Douglas Lake. 



229 



This fish has been taken in all parts of the lake and at all depths between 4 and 45 

 feet. It appears not to go below the thermocline in midsummer, but at other seasons 

 it is possible that, like the sucker, it goes into deeper water. 



Seven of the 22 stomachs examined contained the remains of fish, while the rest 

 were empty. There is no evidence that in midsummer the Douglas Lake pike takes 

 other food than fish. It is clear that the spiny fin rays of such fish as perch do not keep 

 them from the maw of the pike, for in two cases the stomach contents were perch about 

 4 inches long. 



The pike tabulated range in weight from 10 to 104 ounces. We have taken indi- 

 viduals whose weight we estimated at 10 to 12 pounds and those of 18 pounds have been 

 reported by fishermen. Of the 20 whose sex was determined, half were males. The 

 average weight of males is 22.8 ounces, of females 19.6 ounces, but the number of fish 

 used is too small to make the figures significant and includes a single male of 59 ounces. 



A curve showing the relation of length to weight in these 22 fish is sketched in 

 figure 3. The data are insufficient to show more than the general fact indicated for the 

 sucker that there is a definite relation between length and weight of such a sort that, 

 above 8 ounces, the length increases much less rapidly than the weight. The data 

 represented by the curve, although meager, would be of considerable value if there were 

 similar data from other lakes for comparison. It is probable that each species in a lake 

 shows a length-weight curve peculiar to it. It is also probable that curves for the same 

 species from different lakes might be characteristically diS'erent. The form of the curve 

 for a single species from one locality might show to what extent the conditions of that 

 locality are favorable to the species. Unfortunately the literature appears to contain 

 no records full enough for comparison with those of Douglas Lake. Forbes and Rich- 

 ardson (1908) mention for the pike an average length of 36 inches and an average weight 

 of 5 pounds. A curve for the Illinois pike, if it were to pass through the point thus 



