1931 ANNUAL REPORT. 1 '30 51 



Handling of fish prior to transportation requires the utmost care and skill. 

 The surface layer of the body of a fish is very delicate, and touching with dry 

 hands, or causing the slightest abrasion leaves the way open to infection by 

 bacteria or fungus. The greatest care must be exercised in handling fish with 

 dip net, trap, or seine, or whatever type of net is used in coralling the fish for 

 shipment, and in transferring them to the cans or tanks in which they are carried. 

 It is unlikely that the effects of mishandling will be evident at first, but the 

 elimination of such a condition means the removal of at least one factor operating 

 against successful survival. 



The cans or tanks in common use are constructed of durable galv^anized 

 iron. The ordinary fish cans have a carrying capacity of ten gallons and the 

 tanks of seventy-five gallons. The former are painted green on the outside, 

 numbered and labelled in white with the name of the Provincial Government 

 hatchery. When the fish have to be carried for a considerable distance inland, 

 cans of light aluminium ware may be used and are so constructed that they fit 

 the curve of the back. 



The water in the cans in which the fish are transported is maintained at a 

 low temperature. In this way, provision is made for more satisfactory aeration 

 or oxygenation. The amount of oxygen which will dissolve in water depends 

 upon temperature and pressure. If we take distilled water and force oxygen 

 into it, we find that the number of cubic centimetres of oxygen taken up by a 

 litre of water measured at normal temperature and pressure, will decrease with 

 an increase in the temperature of the water. It is necessary, therefore, when 

 we place fish in fresh water in cans or tanks at a hatchery, in preparation for 

 transportation, to make provision for maintaining the water at a low temperature, 

 so that satisfactory aeration or oxygenation may be assured. This is done by 

 having the cans and tanks provided with receptacles which fit into the top in 

 which broken pieces of ice may be carried. The bottom of each type of receptacle 

 is perforated, and as the ice melts the ice-water trickles or drops into the water 

 in the can, keeping it at a low and constant temperature. The more constant 

 the temperature the better, since fish are extremely sensitive to sudden changes. 

 In order to maintain an even temperature, fish cans may be surrounded by canvas 

 insulation, but if plenty of ice is available and transportation rapid, this is 

 unnecessary. Tanks carried in trucks are covered with a suitable tarpaulin. 



If the water in which the fish are carried is maintained at a low temperature, 

 the motion of the water during transit either by rail or in trucks has been found 

 sufficient for satisfactory oxygenation. Hatchery attendants have very little 

 difficulty, providing they check the temperature in the cans regularly and have 

 a supply of ice on hand when required. If the cans are left standing at a railroad 

 station for any length of time, a good way to assist in aeration is to load the cans 

 on one of the platform trucks, and to move it backwards and forwards. This 

 causes sufficient motion of the water to effect suitable aeration. In the case of 

 large tanks, the use of compressed air and oxy-tanks may at times be resorted 

 to. Disturbing the fish by removing water from the can with a dipper and allow- 

 ing it to fall from a height is recommended only in urgent cases, and at all times 

 should be performed with the utmost caution. It is a dangerous practice to use 

 with tiny fry on account of possible injury by forceful impact. In any case, 

 this method excites the fish, with the result that they use up more oxygen and 

 the very end which is being sought is defeated. 



Fish are generally fed the night before shipment is made, in order to avoid 

 the accumulation of excrement in the cans, which would occur if the fish were fed 

 on the day they were shipped. Accumulations of excrement would lead to a 



