52 U. S. BUREAU OF FISHERIES 



tioiis of the dissolved oxygen content and oxygen capacity of the 

 water demonstrated the presence of a considerable amount of unstable 

 organic matter in the water in the vicinity of the ditch leading from 

 the cannery and extending into Cherrystone Inlet. From a 24-hour 

 period of observation of the dissolved oxygen content of the water 

 it was found that the dissolved oxygen in the early morning hours 

 reached the extremely low level of only a few tenths of a part per 

 million. Photosynthesis during the day brought about supersatura- 

 tion of the water with oxygen in the late afternoon. The low oxygen 

 area extended only a short distance into Cherrystone Inlet. On the 

 basis of observations obtained from several trips to the area it was 

 concluded that the high mortality of crabs and fish was a result of 

 insufficient dissolved oxygen in the water, a condition brought about 

 by the emptying of organic matter with high oxygen demand into 

 the inlet by the cannery. 



hwestigations of the periodicity of fouling organisms. — At the re- 

 quest of the Bureau of Construction and Repairs, U. S. Navy Dej^art- 

 ment, an analysis of the fouling organisms grown on experimental 

 panels exposed at Cavite, Philippine Islands, and Guantanamo Bay, 

 Cuba, was undertaken under the direction of Dr. Galtsoff. The work 

 consisted in identifying the principal fouling groups and determining 

 their abundance and the sequence of their appearance. The work 

 was begun in September at the U. S. Fisheries Laboratory at Woods 

 Hole and is being continued now by G. Robert Lunz, Jr., at the 

 Charleston Museum, Charleston, S. C. 



AQUICULTURAL INVESTIGATIONS 



Dr.. H. S. Davis, /;; chanjc 



It is now generally conceded that proper and efficient utilization 

 of the fish resources of our inland waters is to be achieved only 

 through the adoption of a compreliensive plan of fish management 

 adapted to the needs of each body of water. The rapid increase in 

 the number of anglers coupled with the construction of thousands 

 of miles of new highways has resulted in such a drain on the fish 

 population that previous methods of more or less haphazard stock- 

 ing have proved inadequate to cope with the sitaation. 



The need for the development of management plans has served to 

 focus attention on the lack of factual information on which such 

 plans must be based. Although the artificial propagation and rear- 

 ing of trout have been practiced on an ever increasing scale for many 

 years, there is little information on the survival of hatchery fish 

 after being liberated in natural waters. There can be no question 

 that stocking with legal trout shortly before and during the open 

 season has been a success. There are also a few instances where stock- 

 ing with smaller fish is known to have resulted in a material im- 

 provement in fishing. In the great majority of cases, however, there 

 is no evidence that artificial stocking has had a beneficial effect. On 

 the other hand there is considerable evidence that, in many cases at 

 least, stocking has had very little effect on the fish population and 

 that even in heavily stocked waters wild trout frequently make up the 

 bulk of the catch. 



