by virtue of their large amount of free deck space aft are the most 

 versatile type of vessel in existence today, for they can operate 

 purse seines, long lines, otter trawls, siirface or submerged gill 

 nets, and can even operate -with pole and line gear for tuna in a 

 manner similar to the tuna clippero However, with the exception of 

 purse seines, they cannot operate arrjr of these types of gear as 

 effectively as a vessel specifically designed for each purpose. 



Because the bulk of the small-boat albacore fleet is seasonally 

 dependent on other fisheries, there is little probability that there 

 are major changes that covild be made to increase albacore fishing 

 efficiencj'- that -woiiLd not rediice efficiency in the other fisheries 

 in which the vessels engage. 



Refrigeration Equipment 



The ammonia compression system is nearly universal in the tuna 

 fleet. It has a high degree of reliability and effectiveness, and 

 the primary fault night be lack of adequate reserve capacity in some 

 installations. Refrigeration was first introduced in tuna vessels 

 about 1926, and since then constant engineering improvements have been 

 made. The loss through spoilage is very low. Tuna vessel owners are 

 extremely reluctant to experiment ivith other refrigerants or systems 

 which, if they do not function properly, could result in the spoilage 

 of cargo worth fron $30,000 to $180,000, depending on the size of the 

 vessel. 



Compression Freon systems have been tried on tuna vessels but 

 they have been replaced with ammonia systems because of greater 

 reliability. Ammonia absorption systems hold promise, but the un- 

 favorable experiences reported to date with this system in some 

 salmon freezer ships in Bristol Bay, has deterred its introduction 

 in the tuna fleet. The system as applied to fishing vessels still 

 has serious imperfections in such items as liquor r^ransfer primps, 

 and there is a general lack of engineers who can operate absorption 

 systems. Theoretically the equipment and installation costs and the 

 operating and maintenance costs are lower than those of compression 

 systems. Theoretically, also, the absorption system has the 

 advantage of maintaining greater efficiency at low temperatures than 

 ccmpressor systems. However, these theoretical advantages do not 

 outweigh the greater reliability of compressor systems in the mind 

 of the tuna vessel owner. It is also maintained that the lack of 

 e:q)erienced operating engineers has hindered acceptance of ^he 

 absorption system, 



205 



