River Raisin Section 



Section 117. Location, 2 miles ESE. 1/8 E. of 



Monroe Light at the Mouth of River 

 Rciisin. Depth, 6.1 meters. Bottom, 

 sand and gravel. 



Detroit River Section 



Station 126. Location, 2 l/h niiles S. by '.V. 3/U W. 

 of Detroit River Light. Depth, 7.0 

 meters. Bottom, mud and sand. 



Station I3li. Location, 6 1/8 miles W. of Middle 



Sister Island. Latitude, hl» 50.9'; 

 longitude, 83" 07.3'. Depth, 10.0 

 meters. Bottom, mud. 



It was planned originally to make observations at each station in 

 each half-month neriod during the season. For various reasons this pro- 

 gram could not be adhered to strictly. On a lake as large as Lake Erie, 

 winds commonly give rise to seas which are unfavorable for the carrying out 

 of limnological work. In 1930 the program was followed with few irregulari- 

 ties and the data of that year have been found most useful for the purposes 

 of the report. 



Ordinarily, field observations and samples were taken in the morning, 

 and the boat returned to the laboratory about noon to permit analysis of the 

 samples in the afternoon. For the more distant stations, that is, those at 

 the extreme western end of the area, a run was made to Toledo or Amherstburg 

 in the afternoon, and sanples were taken the following morninj;. ',\/here pos- 

 sible, stations were located by means of landmarks. In the case of stations 

 far from land, they were reached by running the boat at a known speed for the 

 proper length of time along the proper course. VoTiile this method does not 

 make possible the occupation of exactly the same point on successive attempts, 

 experience showed that it v;as adequate for the needs of the investi^'.ation. 

 For details concerning methods eirployed in the field and laboratory, the 

 reader is referred to the various chapters in the body of the report. 



Scope of the Report 



Following completion of field work in autumn of 1930, the Bureau of 

 Fisheries assumed the responsibility of assembling the data and preparing 

 a report of the investigation. Owing to the great diversity of subject 

 matter and of contributing, workers, the task of writing a complete and uni- 

 fied report required a long period of time. Dr. Lewis H. Tiffany collabo- 

 rated in writing the chapter on phytoplankton, and Dr. Wilbur M. Tidd in 

 writing the chapter on zooplankton. 



29 



