HEPORT OF THE COMMISSIONER OF FISHERIES XI 



time iiml nianin'r of lil)ei;itioii most productiM' of results in the wa>' 

 of commercially valuable fish. All of the invest ioations beai'injr on 

 the life histories of fish are of importance from the standpoint of fish 

 culture, since they make it possil)le to adjust ai'tilicial proi)a<ration 

 closely to the normal life history. The more closely normal condi- 

 tions can be j)rovided. the oreater the chances will be for success. 

 The study of the physiolotiv and natural food of fresh-water iishes 

 provides data wliich will aid materially in improvin*^ the care aiven 

 both brood tish and youno' at the various stations. 



Special investioations have been carried on by the iish patliolo<rist 

 dealino' with the causes of and remedies for certain diseases that 

 are fre(jnently responsible foi- heavy mortality at the hatcheries. 

 The life history of a pai'asitic fla<rellate (Ocfoniifiis sahnonh) has 

 been almost c<jmpletely worked out. and it is believed that methods of 

 cariuii' foi' the tish will be devised which will materially reduce, 

 if not entirely eliminate, the loss from this source. Very encour- 

 ajjino- results have been obtained in i^reventinjo- thyroid tumor in 

 trout by the administration of iodine. In one lot of over 1,200 

 fish infected witli this disease, no new cases appeared after the be- 

 gin n in o- of the treatment. 



Durino- tlie past year, experiments have been conducted at the 

 Fairport biological station and at several of the fish-cultural sta- 

 tions to determine the etfects of vitamin deficiency on fish. It has 

 been shown that vitamins are just as essential to fish as to higher 

 vertebrates, and it is believed that it will soon be possible t(j i)re- 

 scribe a diet that will be distinctly superior to those now in common 

 nse. 



Plxperiments in the culture of several species of fresh-water fishes 

 of connnercial importance have been conducted at Fairport during 

 the year. These included the lake and shovel-nosed sturgeons, 

 paddlefish, bufi'alofish, sheepshead. channel catfish, and bluegill 

 sunfish. In V.)±l the take of bufi'alofish in the Mississippi drain- 

 age exceeded 17,000,000 i)ounds. with a value to the fishermen in 

 excess of 5^1,000.000. being the most valuable and important species 

 of food fish. Catfishes ranked third in (juantity ancl value, with a 

 catch exceeding 8,000.000 pounds, valued at $Tlo,461. The most 

 successful results were obtained in the case of the butfalofish, chan- 

 nel catfish, and bluegill sunfish. The Iduegills have been propa- 

 gated for a number of years, and it appears probable that the pro- 

 pagation of buifalo and channel cat may be developed to the i)oint 

 where it can be made successful on a larger scale. The so-called 

 •• farm pond *' has l)een conducted as usual. The purpose of this 

 woi'k has ])een to develop methods whereby ponds may be utilized 

 for the production of fish as a part of the regular farming activities. 

 The same pond has been used each year, and no artificial fish food 

 has V)een added to the natural supply in the pond. The bluegill 

 ."^unfish has been used in these experiments, and during the past year 

 a production of 804 pounds per acre was secured. 



MOSQinTO COXTKOI. HV MEANS OF FISH 



The experiments and investigations relating to mosquito control 

 were mainly a repetition of the previous year's Avork, and were 

 continued in cooperation with the United* States Public Health 



