TUBLIC DOCUMENT No. 25. 87 



the effects of the natural conditions upon fish life. In such bodies of water 

 records of temperatures, amount of food (plankton) and general changes 

 which concern the problem of fish life should be followed for a number of 

 years. The work on these type waters should serve as a basis for inter- 

 preting the conditions in other waters of similar nature. 



Ponds. The Massachusetts law provides only for stocking natural 

 ponds over 20 acres in area, excluding all artificial ones. For this reason 

 the survey was limited to the natural ponds over 20 acres, in all about 800. 

 These ponds were examined personally by a representative of the com- 

 mission, and a rapid but comprehensive survey was made. This work 

 was carried on during three summer months for two years by four biolog- 

 ical students. The entire cost was less than $2,000, the greater part of 

 the expenses arising from traveling, owing to the inaccessibility of many 

 ponds. Each man examined approximately 100 ponds in seventy- 

 five days, an average of If ponds per day. The size and importance of 

 the body of water made considerable difference in the amount of time 

 devoted to the examination, the small and less important receiving a 

 rapid survey. At best the examination was hurried and superficial, but 

 it achieved the practical object of providing an inventory of the State 

 ponds, and an available working knowledge of the various bodies of 

 waters. 



The field equipment of the surveyors consisted of a rucksack, a net of 

 silk bolting cloth for towings, hand lens, bottles, vials, formaldehyde, 

 maximum and minimum thermometer, sounding lines and lead, and 

 record blanks. Reports were written approximately at two-week inter- 

 vals, while the towings and other material were sent to the central labora- 

 tory for microscopical examination. As light an equipment as possible 

 was given the field worker, since, in many cases, he had to traverse the 

 territory between one pond and the next by walking. Numerous diffi- 

 culties, such as lack of boats, inability to find the ponds, changes in the 

 maps and lack of transportation facilities, retarded the work. 



Certain ponds in various parts of the State, from Berkshire to Barnstable 

 counties, were selected for type study. The other ponds of the State were 

 placed in these representative classes, each pond falling into the group for 

 which its environment was best adapted. The types under observation 

 were large and small ponds, both deep and shallow, in which the conditions, 

 as regards the species, growth and abundance of fish, were quite different. 

 From the study of the type ponds, and from a classification of the sur- 

 veyed ponds, practical deduction as to the species and amount of fish for 

 the individual ponds of the State could be made. 



In the survey work the following information concerning the physical 

 characteristics of each pond was obtained in order to insure the proper 

 classification for each type. 



(1) Names. The name of the pond is a variable and confusing factor. 

 Usually a pond has several names, according to the various maps upon 

 which it is recorded, and often these listed names are unknown in the 



