On August 3, 1949, the water level at the 

 gauge stood at 649 .65 , 1 .00 feet lower than on 

 the date of the previous operation. This change 

 i-educed the size of area B to approximately 3 

 acres, the maximum depth to 8.0 feet, and the 

 average depth to 4 .0 feet . Neither water temp- 

 erature nor turbidity was determinsd. The 

 vvater was clear enough to permit the bottom to 

 be seen over a major portion of the area . 



On August 14, 1951 , the water level 

 stood at 650.18, 0.53 feet above that of August 

 3 , 1949 , and .47 feet below that of July 7 , 1948 . 

 Deposition of sand had filled one small bay and, 

 together with the lower water level, had re- 

 duced the area to 3.1 acres. The maximum 

 depth was 7.5 feet and the average depth 

 approximated 4 feet. Surface water temp- 

 erature at noon was 73° F . and the silt bottom 

 was visible to a depth of approximately 2 feet. 

 Aquatic vegetation, identified by John Moyle of 

 the Minnesota Department of Conservation was 

 much more abundant than in July, 1948. The 

 following species were present: mud plantain 

 ( Heteranthera dubia), coontail (Ceratophyllum 

 demersum ), western waterweed (Anacharis 

 occidentalis), arrowhead (Sagittaria sp.), sago 

 pondweed ( Pota mogeton pectinatus ), duckweeds 

 (Le mna minor, Spirodela polyrhiza), wild 

 celery (Vallisneria americana), white waterlily 

 (Nymphaea tuberosa), and river pondweed 

 (P otamogeton nodosus ). Coontail was the most 

 abundant species, followed by western water- 

 weed and mud plantain. Arrowhead was abun- 

 dant only at the closed end of the area. 



On September 17, 1952, the water level 

 was 649.90 feet, 0.28 feet below that of August 

 14, 1951, 0.25 feet above that of August 3, 1949, 

 and 0.75 feet below that of July 7, 1948. On 

 the basis of previous plane tabje computations , 

 the size of area B was estimated to be approxi- 

 mately 3.0 acres. The maximum and average 

 depths were 7 .5 and approximately 4 feet , re- 

 spectively. Surface-water temperature at noon 

 was 66° F. Bottom, turbidity, and vegetation 

 were similar to those existing on the date of the 

 preceding operation, August 14, 1951. 



METHODS AND MATERIALS 



Toxicant application 



The methods of applying the fish toxicant 

 followed in each of the six operations were 

 nearly identical. A 0.75 -inch (stretch measure) 

 mesh seine was installed across the open end 

 of each area and the toxicant was then distrib- 

 uted. The seine was laid out early in the morning 

 in 1948 and 1949, in mid-afternoon on the day 

 prior to poisoning in 1951 , and at noon in 1952. 

 The corresponding time for the Miller Lake 

 operation in 1947 is unknown. Diluted toxicant 

 was poured over the side of moving boats pow- 

 ered by outboard motors. During application 

 the areas were repeatedly traversed. Dis- 

 persion of the poison in weedbeds and shallow 

 portions was accomplished with hand scoops or 

 portable hand-operated pumps. Fbwdered derris 

 root warranted 5 percent rotenone (4.5 percent 

 in Miller Lake) was used in the first four op- 

 erations and emulsified rotenone was applied 

 to area B in 1951 and 1952. The concentration 

 of toxicant in all cases was 0.50-0.75 ppm. 



Fish collection 



During the 3 days following application of 

 the toxicant in areas A and B, as many fish as 

 possible were picked up and the small numbers 

 of those remaining were estimated. In Miller 

 Lake an attempt was made to collect all fish 

 except forage species, some young -of -the -year 

 largemouth bass, some yellow perch, and lesser 

 sunfishes and bluegills, under 3.5 inches in 

 length. The estimated members of observed 

 unrecovered fish, primarily of age group 0, 

 in all operations except area B, 1952, were 

 assigned a total weight on the basis of those 

 actually recovered an' weighed. In area B the 

 1952 collection of forage fish and young-of-the- 

 year specimens was considered to be of little 

 utility because a large quantity of small fish 

 was taken by gulls and terns . 



In all operations total length of fish (length 

 from anterior tip of snout to the extreme end of 

 the caudal fin with the lobes compressed) was 

 recorded to the nearest 0.1 inch and weight to 

 the nearest 0.05 pound. General scale samples 

 were taken from areas of the bodies of the vnrious 

 species in accordance with Smith (48). Only 

 length and weight determinations were made of 

 the bowfin, northern longnose gar, shortnose 

 gar, channel catfish, flathead catfish, bullheads, 

 and paddlefish. 



