72 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Obstructions, Buch as dams, waterfalls, etc., in the outlet, and their influence upon the movements of 

 fish; where fish-ladders have been placed and where not. 



Rainfall: Amount for the year; month of greatesl and month of least rainfall. Is the lake subject to 

 any changes or fluctuations iu level? Docs the history of tin- lake show that it is increasing 

 or decreasing in area .' 



Winds: Prevailing direction; any relation noticed between this and character of shore? A compara- 

 tive study of a number of small lakes situated near together would be required in this con- 

 nection. Direction of wind at time of breaking np of ice in spring. In addition to the 

 observations indicated above, the observer should note any and all other physical phenomena 

 which come under his notice, and which have any bearing whatever upon the lake. Few, if 

 any, observations are unimportant, and every fact observed should be carefully recorded. 

 Many of these observations should be repeated as frequently as possible, and at regular 

 intervals. 



BIOLOGICAL FEATURES. 



Botanical: Plants found growing in the water, such as water-lilies, sedges, pickerel-weed, cat-tails, 

 water-arum, rushes, arrow-head, pond-weed, water-milfoil, water-weed, eel-grass, chara, 

 etc.; also the smaller forms, such as the various species of algae, duck-weed, diatoms, 

 desmids, etc. The abundance, distribution, and life-history of each should be studied, 

 especial effort being made to determine as accurately as possible the amount of the various 

 kinds of vegetation found in the lake and the area covered by each. Give much attention to 

 the study of the relations which the various species of plants sustain to the animal life of the 

 lake. Iu studying the life-histories of the various plants, the observations should be as com- 

 plete as possible, paying attention to their growth from first appearance in spring, through 

 flowering and fruiting to time of dying. What becomes of the dead plants and stems — do 

 they sink to the bottom and decay, or are they drifted upon the shores? 



Shore vegetation, including plants growing in or near the water's edge; trees and bushes whose 

 branches overhang the water more or less, and the bearing of these various facts upon the 

 life of the lake. 



Information as to the abundance, character, and distribution of all the species of plants found grow- 

 ing, say within 100 yards of the lake, would be of interest and value. 



ZOOLOGICAL. 



Fishes: As to species, abundance, distribution, and condition; feeding habits, upon what the various 

 species feed, when and how they feed; can any estimate be made as to the amount of food 

 required to supply the fishes of the lake. Breeding habits; when the different species spawn ; 

 location and character of spawning-grounds ; what species feed on the eggs of other species'? 

 Migrations and other movements; where the various kinds of fish are found at different times 

 of the day and at different seasons. Diseases; by what parasites affected, to what extent, and 

 at what season; when is mortality greatest? 



Size: Observe any and all facts which throw any light upon the average size of the individuals of each 

 species ; their age, relation of age to size ; at what age they begin to breed. Note any change 

 in color occurring during the breeding season. 



What food-fishes taken in the lake; extent and value of commercial fisheries, if any; species taken 

 and methods employed; game fishes of the lake; value of the lake to anglers. 



Other animal life found in the lake, such as mollusks, crustaceans, insects, and insect larvae, worms, 

 protozoans, etc., their abundance and distribution; make such observations as you can 

 regarding their habits and study each of these forms with reference to its bearing upon the 

 fish-life of the lake; the relation of these animals to the plants should receive attention. 



Animal life found in the vicinity of the lake that may have any bearing upon that of the lake, 

 such as batrachians, reptiles, muskrats, raccoons, minks, and various species of water 

 birds, such as ducks, snipes, gulls, terns, herons, fish-hawks, etc., the abundance and time of 

 appearance and disappearance of each. Make attempts to determine the abundance of any 

 and all animal forms in and about the lake, especially of those forms serving as food for the 

 fishes. 



