238 BULIvETIN OF THE BUREAU OF FISHERIES. 



individual opened was estimated to contain about four times as many Crustacea as the 

 fecal cord, whose contents therefore represent one-fifth of the food contained in the 

 alimentary canal at the time of capture. The total number of Crustacea in the ali- 

 mentary canals of the 203 young perch at the time of capture was therefore in the neigh- 

 borhood of 812,000. This is not the daily consumption, but represents rather the food 

 taken within a comparatively short time. If one should collect the fecal cords passed 

 by a known number of perch under normal conditions in unit time, there might be 

 obtained a measure of the total daily consumption of microcrustacea per individual. 

 The rate at which food consumption increases and the relation of this increase to the 

 rate of growth might also be thus determined. The whole branchial apparatus of the 

 young perch with its slender, close-set gill rakers forms an excellent instrument for the 

 capture of microcrustacea. 



By an examination of the gonads, the sex of 237 of the perch included in our table 

 was determined. Thirty-six were males and 201 females, a ratio of about i to 6. In 

 two instances our records (table viii, no. i to 71 and 80 to 221) show a considerable 

 number of perch taken at one time and place. These two lots include 36 males and 177 

 females, a ratio of about i to 5. The remaining captures consist of from one to three fish, 

 and in each case in which the sex is recorded the fish are females. The record shows 

 that all the fish under consideration were taken with the gill and fyke nets. It does not 

 show the relative size of males and females. If, as is possible, the males are smaller 

 than the females, the smaller males may pass through the meshes of the nets and the 

 sex ratio found in our collections may be due to the selective action of the nets used. 

 One must be sure that the apparatus does not act selectively before a positive state- 

 ment can be made as to the sex ratio. 



The young perch found on the shoals secure an abundance of food, while the shallow 

 water affords them a refuge from their enemies. When they have reached a length 

 somewhere between 2% and 4 inches they seek larger food among the aquatic vegetation, 

 which at the same time affords them a certain protection from their enemies. Here 

 they remain until they are approaching 6 inches in length. They are then able to 

 leave the aquatic vegetation and wander into deeper water, for their size affords them 

 some protection from pike and bass. They now descend as far as the thermochne and 

 make forays into shallow water beyond the vegetation. 



PERCIna caprodES (Rafinesque), log perch. — Mr. H. V. Heimburger, a research 

 worker at the biological station, reported that he had seen several individuals of this 

 species in water about 3 feet deep at the edge of the vegetation in North Fishtail Bay. 

 In August we have seined them in South Fishtail Bay on the sand bottom near vegeta- 

 tion in 3 feet of water, but they have not been taken in any of the other apparatus 

 used by us. 



We have no records of the stomach contents. Forbes and Richardson (1908) say: 

 "A third of the food of 11 specimens was found by us to consist of crustaceans (mainly 

 Entomostraca) and the remainder of insects, the latter chiefly Chironomus larva, 

 larvae of day flies and water bugs (Corixa)." Their habitat, as judged by the food, is 

 probably the bottom in or near patches of vegetation. 



Between June 28 and July 8, 1912, between 100 and 200 individuals were breeding 

 on the sand shoals at the south end of South Fishtail Bay in water from a few inches to 



