350 FISH HATCHERY MANAGEMENT 



Trucks are the principal means of transporting fish. Most hatcheries 

 currently use vehicles near 18,000 pounds gross vehicle weight (GVW). 

 However, units from 6,000 to over 45,000 pounds GVW often are used for 

 moving fish. 



Automatic transmissions are becoming common in all trucks. Automatic 

 shifting reduces engine lugging or overspeeding, and allows the driver to 

 concentrate on defensive driving rather than on shifting gears. 



Diesel engines also are gaining in popularity. Minimal service and long 

 life are attractive features but the high initial cost is a major disadvantage. 

 Cab-over trucks are popular in many areas especially where a short turning 

 radius is important. Conventional-cab trucks generally are quieter, have 

 better directional stability, and a less choppy ride because of their longer 

 wheelbase. 



A relatively new and promising innovation in warmwater fish transporta- 

 tion is the combined use of gooseneck trailers and pickup trucks. These 

 units are low in cost yet very versatile (Figure 108). 



Tank Design 



Most new fish-distribution tanks are constructed of fiber glass or alumi- 

 num, but plywood, redwood, stainless steel, glass, galvanized iron, and 

 sheet metal all have been utilized in the past. 



Aluminum is lightweight, corrosion-resistant, and easily mass-produced. 

 Alloys in the range 3003H14 to 6061T6 will not cause water-quality prob- 

 lems. 



Fiber glass is molded easily into strong, lightweight tanks and can be 

 repaired readily. Its smooth surface is simple to clean and sanitize. Alumi- 

 num and fiber glass appear equally well- suited for fish- transport tanks. 



Most tanks constructed in recent years are insulated, usually with styro- 

 foam, fiberglass, urethane, or corkboard. Styrofoam and urethane are pre- 

 ferred materials because of their superior insulating qualities and the 

 minimal effect that moisture has on them. A well-insulated tank miminizes 

 the need for elaborate temperature-control systems and small amounts of 

 ice can be used to control the limited heat rises. 



Circulation is needed to maintain well-aerated water in all parts of the 

 tank. Transportation success is related to tank shape, water circulation pat- 

 tern, aerator type, and other design criteria. 



The K factor is the basis for comparing insulation materials. It is the 

 amount of heat, expressed in BTU's, transmitted in 1 hour through 1 

 square foot of material 1 inch thick for each degree Fahrenheit of tempera- 

 ture difference between two surfaces of a material. The lower the K factor, 

 the better the insulating quality. The following is a list of insulating ma- 

 terials and their respective K factors: 



