(7) Ice 1136(1 for preservation should be made of certified 

 pure de-mineralized water. Metal ions in the ice will assist the forma- 

 tion of black spot. Research by the Marine Laboratory of the University 

 of Miami (-onpublished) has shown that clear ice which was aerated while 

 being frozen contained from two to three times as much oxygen when melted 

 as the non-aerated opaque ice. The latter is recommended and is currently 

 being used by many vessels of the Tampa fleet, 



(8) Chilling imparted per unit of time is a function of the 

 surface area of the chilling agent and its temperature. The smaller the 

 ice particles, the greater the area in contact with the shrimp. Observa- 

 tions made at the Marine Laboratory indicate that flat ice surfaces are 

 more efficient than round siirfaces in chilling shrimp, Finely crushed 

 ice preserves shrimp for two or three days longer than the larger "rickey" 

 ice particles. 



In many areas the nightly needs of ice in insulated holds may 

 be supplied by one-ton flake ice machines. Such machines are very compact 

 and are reported in use aboard a number of fishing vessels in Prance. In 

 the domestic fleet such machines would prove particularly useful to the 

 small Atlantic seaboard vessels which, since they rarely fill their hold 

 to capacity, might do with half-ton units. 



Variations in grocery costs betv/een different operations are 

 explainable in terms of the different agreements for compensating crews. 

 Where the crew buys its own groceries before going out on a trip and the 

 boat ovmer does not share in the cost, no charges for this item will be 

 foxind on the books of the vessel operators. Where receipts are divided 

 after deduction of grocery costs, the boat o\nier assumes at least a 

 portion of the costs. In soma instances, particularly in the case of 

 longer trips involving a considerable outlay for groceries, the boat 

 owner guarantees payment of groceries purchased by the crew. The boat 

 owner under these circumstances assumes at least a contingent liability 

 for the payment. 



Packing and Unloadin,? 



Packing and unloading costs are defrayed by the boat owner 

 where these operations are performed by a shrimp plant which does not 

 take title. Where the shrimp plant talces title or where packing and 

 unloading is performed in facilities owned by integrated companies, these 

 costs are not properly chargeable to the boat. Where packing and imload- 

 iig is done on a custom basis for the independent boat owner, the charges 

 made will vary considerably depending on the type of service performed by 

 the shrimp plant. In Mississippi the shrimp plant — at the time the Bu- 

 reau of Business and Economic Research of the University of Miami (1955) 

 made its survey— was receiving 6-1/2 cents per pound of shrimp handled 



21I4 



