IOWA (Cont. ) 



data are collected on production (total number of eggs), number of eggs per 

 quart at various stages of development, fertility, temperatures, and number 

 and sex of fish handled. Some experimental work is being carried on in 

 methods of handling both eggs and fish and in the use of sedatives and pituitary 

 glands. 



Began April 1946, continuing; $750; Tom Moen, Garfield Harker, and Bob 

 Stoker, Leaders. 



Address inquiries to: E. B. Speaker, as in No. 7 above. 



16. Natural Lakes Survey 



All of the natural lakes managed for angling are surveyed each year. This 

 involves test sening with 500 feet of l/4-inch mesh (bar) seine at several sta- 

 tions on each lake. Pound and gill nets are used to supplement the seine 

 catch. The small-mesh seine hauls are designed to determine primarily the 

 magnitude of reproduction each year, and the nets to determine population 

 fluctuations and status of the adult fishes. Fishes taken are sorted into 

 young-of-the-year and older groups, weighed, measured, and scale samples 

 taken from representatives for age and growth analyses. Data on vegetation, 

 amount of bottom foods (dredge samples), turbidity, and lake chemistry are 

 also obtained. Electro-fishing devices, both AC and DC, were used to supple- 

 ment nets and seines in the population studies in 1956. 



Statewide; began July 1940, continuing; $7500; E. T. Rose, Leader; reports 

 available. 



Address inquiries to: E. B. Speaker, as in No. 7 above. 



17. Artificial Lakes Survey 



A continuing inventory is maintained in the form of an aruiual netting sur- 

 vey, electrical shocker sampling, and limited limnological investigations of 

 the artificial lakes. Although special emphasis is placed on the relative abun- 

 dance of each species and extent of reproduction, other itenns such as age and 

 growth, abundance of bottom fauna, extent and species of vegetation, turbidity, 

 and extent of chemical and thernnal stratification are determined. 



Southern Iowa; began September 1947, continuing; $3000; James Mayhew, 

 Leader; reports available. 



Address inquiries to: E. B. Speaker, as in No. 7 above. 



18. Continuing Inventory of the Fishes of Iowa Streams 



The project involves population trend determinations by netting surveys 

 at fixed stations. Each survey station is visited annually at the same time 

 each successive year to approximate similar ecological conditions. Speci- 

 mens are taken with trap and hoopnets and the data are handled on a catch 

 and weight per net-hour basis. Reproduction indices are gathered at the sta- 

 tion by use of a 25-foot drag seine. The geographical distribution of the various 

 species in the State is recorded. 



Statewide; began June 1949, continuing; $8000; H. M. Harrison and R. E. 

 Cleary, Leaders; reports available. 



Address inquiries to: E. B. Speaker, as in No. 7 above. 



19. Creel Census of Artificial Lakes 



The objective is to determine the success of anglers on the artificial lakes 

 in Iowa. In addition to the creel census on six lakes information was gathered 

 from boat liveries on four additional lakes. This technique was designed to 

 (1) census a segment of the angler harvest, (2) compare incomplete with 

 completed fishing trip harvest, and (3) to design an economical means of 

 sampling with the minimum of expense and effort. 



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