The Praductivily of Fish Pood in Oneida Lake 89 



other words we must know the mutual relations between all 

 the aquatic organisms before we can hope to successfully dis- 

 turb the lialance of nature l)y artificial fish culture. It is the 

 I)uri)ose of this cha])ter to indicate the valuation of the bottom 

 animals and plants of Lower South Bay. The number of ani- 

 mals on each kind of bottom will be considered and these 

 results will l)e used to determine as accurately as possible the 

 value of this life to the fish fauna as food. As stated by 

 Petersen, this will afford a basis for cf)mparison with other 

 bodies of water. 



As indicated in the introduction, collections were made on 

 soft bottoms (mud, sand, and clay) with a Walker dredge 

 flattened on one side so as to scrape up a portion of the 

 bottom measuring about 10 centimeters square, or 100 square 

 centimeters (the area covered was slightly more than 100 

 square cm., being four inches square or 16 square inches). 

 This is about the area used by Petersen in his marine investi- 

 gations (one-tenth of a square meter or 3.93 inches square = 

 about 15.-14 square inches). Petersen's bottom sampler is 

 useful only on a soft bottom and its small size causes it to miss 

 large animals, as large mollusks of the sea and the fresh-water 

 clams of our lakes, and it might be desirable to use a larger 

 sampler when investigating a bottom containing quantities of 

 the large animals. F.kman ('15, p. 166) has devised a bottom 

 sampler covering an area 5 decimeters square, but this seems 

 almost too large for practical work. For soft bottoms upon 

 which quantities of small animals live the Petersen bottom- 

 sampler is the best apparatus known for obtaining accurate 

 statistical data. A Petersen bottom-sampler was not available 

 for use during the 1916 field season, and the Walker dredge 

 was found to be satisfactory in the shallow water (down to 

 six feet). The deeper parts of the bay were dredged with the 

 ordinary rectangular dredge, a small area approximately 

 16x48 inches, being covered at each haul (see p. 23). For 

 rocky shores the only method was to examine a number of 

 boulders, measure them, and pick off all the animal and vege- 

 table life. As is' usually the case in general field work it was 

 found that the best results Avere obtained by using a variety 



