32 



BULLETIN 908, U. S. DEPARTMENT OF AGRICULTURE. 



These experiments show that as a means of preservation in the 

 transportation of the small sea herring, refrigeration is in every 

 respect far superior to the use of salt. This is apparent from a com- 

 parison of the physical condition of the two lots of fish at the different 

 intervals of time, and is confirmed by the analytical results. The 

 same degree of decomposition in the viscera and contents of the fish 

 carried under refrigerator conditions as that found for the 8- to 10- 

 hour period in the case of the fish in salt is not shown until the end 

 of from 25 to 30 hours. 



The difference between the appearance of fish transported under 

 refrigeration and that of those carried an excessive length of time 

 in salt is shown in Plates XII and XIII. Kept in compartments 

 surrounded with ice and salt they are plump and firm, and look like 

 fresh fish, even after they have been 30 hours out of water. The 

 fish carried an excessive length of time in salt, in bulk, are poorer in 

 appearance, and much thinner, and have been pressed out of shape. 

 Each lot of fish at the time of capture varies in the amount and 

 kind of food in the digestive tract, and also in the bacterial con- 

 tamination of the digestive tract. The keeping qualities, or the rate 

 of decomposition, of different lots of fish should therefore vary 

 directly as the contamination and quantity of feed vary. That 

 this is true is shown by the differences in the time and extent of 

 spoilage of the various lots of fish employed ha these experiments. 



Temperature Changes Occurring in Loads of Fish During Transportation. 



Temperature observations were made on boatloads of fish trans- 

 ported from the weirs to the canneries in pickle and in dry salt. It 

 was estimated that the fish in the three lots studied contained dif- 

 ferent proportions of feed. The results are given hi Table 11. The 

 temperature measurements were accurately made by means of a 

 Leeds and Northrup potentiometer, the thermocouple of which was 

 inserted in the mass of fish in the boats, and readings taken at the 

 time intervals indicated. The temperature changes of the air on 

 the warmest day of the month and the changes shown from the 

 mean temperatures for the month in which these observations were 

 made are included in the table. 



Table 11. — Temperature changes in loads offish during transit. 



FLOATED IN BRINE CONTAINING 150 POUNDS OF SALT TER HOGSHEAD OF FISH; 

 SLIGHT AMOUNT OF FEED PRESENT. 



Temperature. 



Time 

 observed. 



Of air.' 



Offish. 



Warmest 

 day. 



Mean for 

 month. 



a. m. 

 6.30 

 7.00 

 7.30 

 8.00 



° C. 

 12.7 



° c. 



6.9 



° C. 

 12 

 13 

 15 

 16 







13.8 



8.2 



i From hourly thermograph readings taken from original monthly reconl of observations at Eastport, 

 Me., for October, 1916 (courtesy of U, S. Weather Bureau), 



