16 FISH AND GAME COMMISSION 



Tulare Lake in 1942 but to a lesser degree than in previous years. The 

 1943 infection was about the same as in 1942. 



1942 — 461 ducks picked up — 388 banded aud released — 73 lost 

 1943 — 576 dncks picked up — 484 banded aud released — 92 lost 



1.5.6 per cent loss in 1942 



16.2 per cent loss in 1943 



For comparison the 1941 figures show : 5,711 ducks picked up ; 4,912 

 banded and released ; 799 lost, 13.9 per cent loss. The radical difference 

 in the number of sick birds was evidently due to the change made by the 

 farmers in the management of their irrigation water during the late 

 summer and fall. They began the new system in 1942, whereby the water 

 was kept moving from one field to the next lower one as soon as the first 

 field was flooded and soaked. The intervening levee is cut and the water 

 kept moving from one field to the next until the irrigation is completed. 

 On completion of the irrigation, water is pumped back into the lake. 

 This system keeps the water moving and does not give the vegetation time 

 to start decomposing in the warm standing water. The old system of 

 allowing fields to remain flooded for weeks at a time found the water 

 temperatures rising and heavy decomposition with a corresponding 

 decrease of oxygen content in the water. The botulinus bacillus thrived 

 in such a medium. Under the new system most of the duck disease was 

 found in low, undrained spots on the fields and in barrow pits. 



The fall duck population has increased steadily in the Tulare Lake 

 region each year since 1938. The 1942 and 1943 peak populations were 

 not radically different. The 1942 peak was on or about October 8th, 

 when 3,500,000 were estimated to be in the area, and the 1943 peak was 

 on October 10th, with 4,000,000 birds estimated to be present. 



Water surface temperature, bottom temperatures, sun temperatures, 

 shade temperatures, wind direction and velocity, and general weather 

 conditions were noted and correlated with the severity of the disease. 



Intensive study has been given the problem of providing shooting 

 areas for unattached duck hunters. To R. E. Curtis, a member of the 

 staff, was given the task of working plans of procedure and operation. 

 His approved report follows : 



WATERFOWL PUBLIC SHOOTING GROUNDS IN CALIFORNIA 

 Suggested Management Practices and Estimated Costs 

 Objectives 



"Waterfowl management in California presents problems that are 

 probably unique in the United States. Reclamation has reduced and 

 agriculture has encroached upon the natural waterfowl habitat to an 

 extreme extent. 



Public shooting grounds in this State will have two principal objec- 

 tives : (1) To provide the unattached hunting license holder with a 

 place to shoot at reasonable cost. (2) To control and minimize water- 

 fowl depredation on agriculture. 



To accomplish the first purpose it will be necessary to bring under 

 control of the Division of Fish and Game, by purchase, lease, or otherwise, 

 large tracts of strategically located, suitable land, and to so administer 

 these areas that the greatest possible number of hunters may be accom- 

 modated with reasonably good shooting. 



